tag:blogger.com,1999:blog-75100487155123227152024-03-17T20:01:17.599-07:00cryology and co.Because Quaternary is more then a bunch of dirt...David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.comBlogger180125tag:blogger.com,1999:blog-7510048715512322715.post-20536227091826870402011-07-07T08:12:00.001-07:002011-07-07T08:12:58.996-07:00The discovery of the periglacial realm<div style="text-align: justify;"><span style="font-family: arial;">The term periglacial was introduced by the Polish geologist </span><em style="font-family: arial;">Walery von Lozinsk</em><span style="font-family: arial;"> in 1910 and 1911 to describe the particular mechanical weathering he had observed in sandstones of the Gorgany Range in the southern Carpathian Mountains - today the reactions of the permafrost to changing temperatures is one of the major fields of research. Read more about the periglacial realm on the <a href="http://blogs.scientificamerican.com/history-of-geology/2011/07/07/the-discovery-of-the-periglacial-realm/">American Scientific Blog</a>.</span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com10tag:blogger.com,1999:blog-7510048715512322715.post-56638009811974479272011-02-18T09:09:00.000-08:002011-02-18T09:10:04.605-08:00Climate research in the geologic past<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxRFgAvx4eNcmI4eCCWdx487OUcCL6y9TQJg0GNRlzw2GmGfe68Oc94km-Rou7dWi7CNq45vXLbWHNMV8etxkeWyMR5HzwZjCHq5MZIZrQsyVQ1xkelbXn7S32GYcoXrVJj4hJyvEVQXU_/s1600/LYELL_1850_Map_Climate.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 384px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxRFgAvx4eNcmI4eCCWdx487OUcCL6y9TQJg0GNRlzw2GmGfe68Oc94km-Rou7dWi7CNq45vXLbWHNMV8etxkeWyMR5HzwZjCHq5MZIZrQsyVQ1xkelbXn7S32GYcoXrVJj4hJyvEVQXU_/s400/LYELL_1850_Map_Climate.jpg" alt="" id="BLOGGER_PHOTO_ID_5575075994899358802" border="0" /></a><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.1. </span>Global map as published by Lyell in his "<span style="font-style: italic;">Principles of Geology</span>" (8th edition 1850) to illustrate the past climatic changes. </span></span><br /><br /><div style="text-align: justify;"><span style="font-family:arial;">The climate of a region, as experienced by daily observations of a cool morning and hot midday, was for very long time considered simply the result of the height of the sun above the horizon. This idea forced a very simple view of the distribution of climates on Earth, to the poles temperature dropped, to the equator it raised, forming so large parallel climatic belts. Such a static view of the Earth also didn’t need or even allow climate changes in the past or in the future time.</span> <span style="font-family:arial;"><br />With the establishment of the deep geological time by the first geologists and naturalists it became clear that not only the distribution of sea and land changed over time, but so did climate.<br /><br /></span><div style="text-align: center;"><span style="font-family:arial;">Read on how Lyell explained climate change by shifting "pseudo"-continents over the globe in the post at the <a href="http://www.scientificamerican.com/blog/post.cfm?id=climate-research-in-the-geological-2011-02-17">American Scientific Guest Blog</a>.</span><br /></div></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com31tag:blogger.com,1999:blog-7510048715512322715.post-36436914899111051372011-01-11T11:03:00.000-08:002011-01-11T11:06:54.364-08:00Glacier outburst floods threat<div style="text-align: justify;"><span style=";font-family:arial;font-size:100%;" >Glaciers can influence societies in their catchment area in different ways, they act as a water <a href="http://historyofgeology.blogspot.com/2010/11/quantifying-importance-of-glaciers.html">storage for dry summers</a>, but glaciers can also trigger geological catastrophes and endanger people.<br /><br />Glacier outburst floods (GOF) refer to the rapid and sudden discharge of water from within a glacier or from an ice-dammed lake, within minutes to hours a flood wave occurs possibly damaging infrastructures and killing people kilometres away from the glacier which initiated the disaster. In the Alps and North America most outburst floods </span><span style=";font-family:arial;font-size:100%;" >occur in summertime when during melt-season large quantities of water can accumulate inside the glacier or as ice-dammed lake.<br /><br />In the Andes and the Himalaya also a second type of floods is </span><span style="font-family:arial;">common, outbursts from moraine-dammed lakes, referred as glacial lake outburst flood (GLOF).<br />The area between the moraine and the retreating glacier can be filled with the melt-water, and as the glacier continues to shrink the lake continues to grow. </span><span style="font-family:arial;"> Various processes can lead to the failure of a moraine dam, waves and currents of the lake can erode the dam, ice contained in the dam can melt, the detritus forming the dam can settle with time and so lowering the effective height of the dam.</span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8HWu0TCINqhfzE-Zd6H1WPQvGRxv6B88V1YirlJE2FhiX0WQp2Eg6w9L7eMBj1Us7F7zBzyPggoSOGn1FfrWfV1Hr6aAse4EW9jamNINetj7zwvzQoPEbMlvtgB1cxT51rwqW7b8Kehj/s1600/Paron_Lake.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8HWu0TCINqhfzE-Zd6H1WPQvGRxv6B88V1YirlJE2FhiX0WQp2Eg6w9L7eMBj1Us7F7zBzyPggoSOGn1FfrWfV1Hr6aAse4EW9jamNINetj7zwvzQoPEbMlvtgB1cxT51rwqW7b8Kehj/s400/Paron_Lake.jpg" alt="" id="BLOGGER_PHOTO_ID_5560995281729851762" border="0" /></a><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.1.</span> <a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=bam&sll=46.641717,12.35816&sspn=0.039776,0.090895&ie=UTF8&hq=&hnear=Bam,+Kerman,+Iran&t=h&ll=-8.999704,-77.666988&spn=0.057222,0.090895&z=14"><span style="font-style: italic;">Laguna Paron</span></a> (4.140m a.s.l. Cordillera Blanca - Peru, foto from <a href="http://en.wikipedia.org/wiki/Lake_Par%C3%B3n">Wikipedia</a>) in 2009, a lake dammed by the debris-mantled glacier <span style="font-style: italic;">Hatunraju</span> with a capacity of 75 million cubic metres before the lake level was lowered by 20 meters artificially by tunnelling through be</span></span><span style="font-size:100%;"><span style=";font-family:arial;font-size:85%;" >drock on the left of the moraine dam. The lake is surrounded by moraines 250m high.</span><span style="font-size:85%;"> </span><span style=";font-family:arial;font-size:85%;" >It is unknown how stable the moraine of Hatunraju is, if this dam fails a flood of around 50 million cubic metres could sweep downstream and severely damage the town of Caraz, 16 kilometres away.</span><span style="font-size:85%;"> </span><span style=";font-family:arial;font-size:85%;" ><br />The worst glacial lake outburst in historic time was caused by the failure of such a moraine-dam in Peru. December 3. 1941 the town of Huaraz was partially destroyed by a flood that killed 60.000 people.</span><br /><br /><span style="font-family:arial;">Floods resulting from moraine-dam failure have been increasing in frequency in the Himalaya over the past 70 years or so, although in terms of loss of life they have been by accident much less disastrous then in the Andes.</span> <span style="font-family:arial;"><br />One of the best-documented outburst floods in Nepal took place on 4. August 1985 when the terminus of the <span style="font-style: italic;">Langmoche</span> Glacier in the Khumbu Himal collapsed into <span style="font-style: italic;"><a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=Dig+Tsho&sll=28.103632,90.290279&sspn=0.10221,0.181789&ie=UTF8&ll=27.864726,86.60162&spn=0.102436,0.181789&t=h&z=13">Dig Tsho</a> </span>glacial lake (<a href="http://www.youtube.com/watch?v=J_G2vaaswn0">Video</a>), creating a displacement wave hat overtopped the moraine dam and triggered its collapse. Estimated 10 million cubic metres of water were releas</span></span><span style="font-size:100%;"><span style="font-family:arial;">ed - the wave destroyed a power plant and five people were killed and eroded and destabilized the valley floor for 90 kilometres downstream.</span> <span style="font-family:arial;"><br /><br />This case triggered major research projects of potential dangerous glaciers and glacial lakes, until 2004 more then 20 potentially dangerous lakes in Nepal and 24 in Bhutan were identified, one of the most impressive and dangerous case was lake <a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=Kathmandu,+Central+Region,+Nepal&sll=27.469287,88.621216&sspn=3.28945,5.817261&ie=UTF8&hq=&hnear=Kathmandu,+Bagmati,+Central+Region,+Nepal&ll=27.858352,86.47871&spn=0.102442,0.181789&t=h&z=13"><span style="font-style: italic;">Tsho Rolpa</span></a> (4.450m a.s.l.), fed by the <span style="font-style: italic;">Trakarding</span> Glacier. By 2002 the l</span></span><span style="font-size:100%;"><span style="font-family:arial;">ake was 3,5 kilometres long, 0,5 kilometres width and 135m deep, with an estimated volume of 110 million cubic metres. The moraine damming the lake up was 150m high, with a core of decaying ice.</span> <span style="font-family:arial;"><br />Emergency measures were initiated with the installation of an early-warning system to detect downstream travelling a flood-wave and later by the construction of an artificial spillway, lowering the lake by 4 metres.</span> <span style="font-family:arial;"><br />However these are considered only temporary solutions, as a lowering of the lake level by at lest 15 to 20 metres is necessary to prevent spillover or failure of the dam crest, a costly procedure in this region.</span> <span style="font-family:arial;"><br /><br />This last case shows also the financial problems facing poor countries, often disaster prevention or mitigation are limited by the available resources, and considering the <a href="http://historyofgeology.blogspot.com/2011/01/modeling-glacier-change-2000-2100.html">continuing glacier retreat expected in the next decades</a> the increase of problematic lakes (both in number and volume) will by of major concern in the future.<br /></span> <span style="font-family:arial;"><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhP09PgzQtgCOCxyRo3bBXMTSPVL05hB1r8vIt2lNEgG_9oveowY1G8Yymf7-LzcfeF4N6S4q8nRH9oLt4bwD5XbxUXU5HahClF2XxN4cYjlrKOR_mRoHpp2ZbRNIMWeyWEHGadt3m6dvCE/s1600/NASA_ASTER_Bhutan_Glaciers.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 222px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhP09PgzQtgCOCxyRo3bBXMTSPVL05hB1r8vIt2lNEgG_9oveowY1G8Yymf7-LzcfeF4N6S4q8nRH9oLt4bwD5XbxUXU5HahClF2XxN4cYjlrKOR_mRoHpp2ZbRNIMWeyWEHGadt3m6dvCE/s400/NASA_ASTER_Bhutan_Glaciers.jpg" alt="" id="BLOGGER_PHOTO_ID_5560993727165596226" border="0" /></a><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> The glacierized Himalayan border region of Bhutan (bottom) and Tibet (top) seen in a satellite image. From the crest of the mountain range clean glaciers flow northwards onto the Tibetan Plateau, while debris-mantled glaciers flow south into densely forested valleys.<br />At bottom right are a series of moraine-dammed lakes and incipient lakes, formed by the rapid coalescence of supraglacial ponds. The large lake at the very right is <a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=Kathmandu,+Central+Region,+Nepal&sll=27.469287,88.621216&sspn=3.28945,5.817261&ie=UTF8&hq=&hnear=Kathmandu,+Bagmati,+Central+Region,+Nepal&t=h&ll=28.103632,90.290279&spn=0.10221,0.181789&z=13">lake </a></span><span style="font-style: italic;font-size:85%;" ><a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=Kathmandu,+Central+Region,+Nepal&sll=27.469287,88.621216&sspn=3.28945,5.817261&ie=UTF8&hq=&hnear=Kathmandu,+Bagmati,+Central+Region,+Nepal&t=h&ll=28.103632,90.290279&spn=0.10221,0.181789&z=13">Luggye Tsho</a>.</span><span style="font-size:85%;"> A breach of the dam in 1994 led to severe flooding and loss of life up to 200 kilometres downstream. (<a href="http://visibleearth.nasa.gov/view_rec.php?id=2876">ASTER-image by NASA, 08 June 2006</a>)</span></span><span style="font-size:85%;">. </span><span style=";font-family:arial;font-size:85%;" ><br /><br />Bibliography:</span> <span style=";font-family:arial;font-size:85%;" ><br /><br />HAMBREY, M. & ALEAN, J.(2004): <a href="http://www.swisseduc.ch/glaciers/earth_icy_planet/glaciers13-de.html?id=7">Glaciers.</a> 2nd ed. Cambridge University Press: 377<br /></span><span style=";font-family:arial;font-size:85%;" >HORSTMANN, B. (2004): <a href="http://www.blogger.com/www.germanwatch.org/download/klak/fb-gl-e.pdf">Glacial Lake Outburst Floods in Nepal and Switzerland.</a> New Threats Due to Climatic Change. Germanwatch - Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung.</span> <span style=";font-family:arial;font-size:85%;" ><br />KALTENBORN, B. P., NELLEMANN, C., VISTNESS, I. I. (Eds) (2010): <a href="http://www.grida.no/publications/high-mountain-glaciers/">High mountain glaciers and climate change - Challenges to human livelihoods and adaptation</a>. United Nations Environment Programme, GRID-Arendal.</span><span style="font-family:arial;"><br /></span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com11tag:blogger.com,1999:blog-7510048715512322715.post-17667150945983110612011-01-10T09:41:00.000-08:002011-01-10T09:42:04.752-08:00Modeling Glacier Change 2000-2100<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">According to a simulation by researchers of the University of Alaska </span></span><span style="font-size:100%;"><span style="font-family:arial;">(RADIC, V. & HOCK, R.) </span></span><span style="font-size:100%;"><span style="font-family:arial;">and based on various scenarios of precipitation change and a temperature increase, with a mean value of ca. 2°C, as predicted by most climate models, until the year 2100 the 120.000 glaciers located (mainly) in middle latitudes will experience a massive loss of 21% of th</span></span><span style="font-family: arial;">e actual ice volume.</span><br /></div><div style="text-align: justify;"><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">Observing the reactions of more than 300 glaciers to the climatic change in the period of 1963 to 2004 the models were extrapolated to simulate a significant increase in temperature and slight increase in precipitation and the effects of these variables on the mass b</span></span><span style="font-size:100%;"><span style="font-family:arial;">alance of the glaciers.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">The projections show in the 19 chosen glacierized regions diffe</span></span><span style="font-size:100%;"><span style="font-family:arial;">rent glacier retreat values, depending from factors like elevation, surface properties and effective temperature rise in the region.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">According to the propose</span></span><span style="font-size:100%;"><span style="font-family:arial;">d scenarios, mountain ranges in temperate climatic zones will experience the most massive volume change, in the European Alps glacier will loss up to 75% of the actual ice volume, similar values to the New Zealand Alps with 72% and the Cauc</span></span><span style="font-size:100%;"><span style="font-family:arial;">asus.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">In contrast mountain ranges with a high average altitude, like in Asia or the Andes, will experience much lower loss percentages, with an average value of 20%.<br /><br />I discussed a previous research dealing with possible effects of such glacier retreat on human society in <a href="http://historyofgeology.blogspot.com/2010/11/quantifying-importance-of-glaciers.html">this post</a>.<br /></span></span></div> </div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2PUoVjzAAnhqlfQUGgN1P36kg-t7MSRvMJbw6XKEc7tHqx7Hd7WTk5H3Njd513EPl1IE0fi7COYV3N60nhfMqr1AiGz3zIi0mXRToPrLquCUgeAKLsJcmCaJ1SPzQAwXA5BPWcZ7KRtUM/s1600/RADIC_2011_Glaciers.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 356px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2PUoVjzAAnhqlfQUGgN1P36kg-t7MSRvMJbw6XKEc7tHqx7Hd7WTk5H3Njd513EPl1IE0fi7COYV3N60nhfMqr1AiGz3zIi0mXRToPrLquCUgeAKLsJcmCaJ1SPzQAwXA5BPWcZ7KRtUM/s400/RADIC_2011_Glaciers.jpg" alt="" id="BLOGGER_PHOTO_ID_5560604385357521986" border="0" /></a></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> Regional twenty-first-century glacier volume change expressed in per cent from initial volume in year 2000, the results are presented for 19 regions based on temperature and precipitation projections from the ten applied climatic models, after </span></span></span><span style=";font-family:arial;font-size:85%;" >RADIC & HOCK 2011.</span><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaFyskO4ajTS3KY1MUAo7lNAovukz486UcK1W6OYJwWtHulHnCGBiRz3FcSAMUzrRhumK0puP6QDoSCm6VHXvU_EeS7pSMrfGtFvA_0pLzq9T82Gf2SSM5Abya9XRUGNWbvqoL_SSmOQHS/s1600/Zillertal_1900.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 229px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaFyskO4ajTS3KY1MUAo7lNAovukz486UcK1W6OYJwWtHulHnCGBiRz3FcSAMUzrRhumK0puP6QDoSCm6VHXvU_EeS7pSMrfGtFvA_0pLzq9T82Gf2SSM5Abya9XRUGNWbvqoL_SSmOQHS/s400/Zillertal_1900.jpg" alt="" id="BLOGGER_PHOTO_ID_5560605437159531666" border="0" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizxA04vCosG66KoyY1iyBOkHwG7FjsTgViADbeoEXNMYs1tTaZMNqGJb5rrLnkxiKXRpDzoVNSeTBNFotoQWjFKjl6xiKsFnEIXvXBkv7EfrV_YwroMCRxePYF7vnPSn4s1cVEcWLw37G-/s1600/Zillertal_2000.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 259px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizxA04vCosG66KoyY1iyBOkHwG7FjsTgViADbeoEXNMYs1tTaZMNqGJb5rrLnkxiKXRpDzoVNSeTBNFotoQWjFKjl6xiKsFnEIXvXBkv7EfrV_YwroMCRxePYF7vnPSn4s1cVEcWLw37G-/s400/Zillertal_2000.jpg" alt="" id="BLOGGER_PHOTO_ID_5560605560730293890" border="0" /></a><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.2. </span>Example of glacier retreat in the Alps in the past 100 years: <a href="http://maps.google.at/maps?f=q&source=s_q&hl=de&geocode=&q=bam&sll=46.641717,12.35816&sspn=0.039776,0.090895&ie=UTF8&hq=&hnear=Bam,+Kerman,+Iran&t=h&ll=47.010109,11.850042&spn=0.037924,0.090895&z=14">The Waxegg-glacier in the Zillertaler Alps </a>at the border between Austria and Italy ca. 1900-1903 and 2006. Historic image from ROTHPLETZ, A. & PLATZ, E. (1903): <span style="font-style: italic;">Alpine Majestäten und ihre Gefolge - Die Gebirgswelt der Erde in Bildern, 268 Ansichten aus der Gebirgswelt.</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">For the history of glacier monitor projects see <a href="http://historyofgeology.blogspot.com/2010/12/discovery-of-ruins-of-ice.html">this post</a>.</span></span><br /><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><span style="font-family:arial;">Bibliography:</span><br /><br /></span><span style="font-size:85%;"><span style="font-family:arial;">RADIC, V. & HOCK, R. (2011): <a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1052.html">Regionally differentiated contribution of mountain glaciers and ice caps to future sea-level rise.</a> Nature Geoscience doi:10.1038/ngeo1052</span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com2tag:blogger.com,1999:blog-7510048715512322715.post-6791871439709399752011-01-03T11:31:00.001-08:002011-01-03T11:31:25.550-08:00Cool Science at Scientific American<div style="text-align: justify;"><span style="font-family:arial;">Since antiquity snow-covered peaks have been ignored, avoided or even feared by men - up here apparently there was nothing to be gained. </span> <span style="font-family:arial;"><br />But in search of adventure and knowledge during the 19th century mountains and glaciers became more and more visited by mountaineers, naturalists and even queens - and today the science of glaciers demonstrate urgently how the climate and our interference is changing the world. </span><br /><br /><span style="font-family:arial;">Thanks to <a href="http://blog.coturnix.org/">Bora Zivkovic</a> and the editors of <a href="http://www.scientificamerican.com/">Scientific American</a> I was allowed to present <a href="http://www.scientificamerican.com/blog/post.cfm?id=the-discovery-of-the-ruins-of-ice-t-2011-01-03">A Short History of Glacier Science</a></span><span style="font-family:arial;"> at the journal´s <a href="http://www.scientificamerican.com/blog/guest-blog/">Guest Blog</a>.</span><br /><br /></div><div style="text-align: justify;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2B_mUDbzx-lnogO5fdImoRd_e_dkUz_CgDYDfVSGIVSdFFvogRFYB_4btU_v8i0ANtQSirf5DZlubhaMacRgf0XxNI1J-cRwERnu2XVewA8zH4AVmtQ8xudNdL-LgxS6-jSoDEyAOOXKy/s1600/1893_Monte_Rosa.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 256px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2B_mUDbzx-lnogO5fdImoRd_e_dkUz_CgDYDfVSGIVSdFFvogRFYB_4btU_v8i0ANtQSirf5DZlubhaMacRgf0XxNI1J-cRwERnu2XVewA8zH4AVmtQ8xudNdL-LgxS6-jSoDEyAOOXKy/s400/1893_Monte_Rosa.jpg" alt="" id="BLOGGER_PHOTO_ID_5558039964015296642" border="0" /></a><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.1.</span> Queen Margherita of Italy (second from left) and company climbing the Monte Rosa (4.420m) in the Italian-Swiss Alps in the year 1893. The Queen was determined to inaugurate in person a weather station on the summit on the mountain (from BAILEY 1983).<br /><br />Bibliography:<br /><br />BAILEY, R.H. (1983): Glacier. Time-Life Books, Amsterdam: 176<br /></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-85349774644358827132010-12-21T09:08:00.001-08:002010-12-21T09:08:48.267-08:00The discovery of the ruins of ice<div style="text-align: justify; font-style: italic;"><span style="font-family:arial;">"It has already been said, that no small part of the present work refers to the nature and phenomena of glaciers. It may be well, therefore, before proceeding to details, to explain a little the state of our present knowledge respecting these great ice-masses</span><span style="font-family:arial;">, which are objects of a kind to interest even those who know them only from description, whilst those who have actually witnessed their wonderfully striking and grand characteristics can har</span><span style="font-family:arial;">dly need an</span><span style="font-family:arial;"> inducement to enter into some inquiry respecting their nature and origin."</span><br /></div><div style="text-align: justify;"><span style="font-family:arial;">James, D. Forbes (1900): "<span style="font-style: italic;">Travels Trough the Alps.</span>" [page 17]<br /><br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoLTH-kBNRy7QrT60mnj-sKaxjaaYjIU5QPi8GUZ0sqjZcOi0BNJHyv3-2Blf01RqbD9z-UgiIazAoLwXhJgpK759iY8ehlryCwV7lzwBi4PEnSVWd0dhr4Yp59Sncy4tE4rlk1kjvDwFx/s1600/WOLF_DESCOURTIS_1785_Glacier_Vorderaar.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 271px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoLTH-kBNRy7QrT60mnj-sKaxjaaYjIU5QPi8GUZ0sqjZcOi0BNJHyv3-2Blf01RqbD9z-UgiIazAoLwXhJgpK759iY8ehlryCwV7lzwBi4PEnSVWd0dhr4Yp59Sncy4tE4rlk1kjvDwFx/s400/WOLF_DESCOURTIS_1785_Glacier_Vorderaar.jpg" alt="" id="BLOGGER_PHOTO_ID_5553175161232883826" border="0" /></a><span style="font-family:arial;"><span style="font-weight: bold;font-size:85%;" >Fig.1.</span> </span><span style=";font-family:arial;font-size:85%;" >C. Wolf and M. Descourtis "<span style="font-style: italic;">La Grosse Pierre Sur Le Glacier de Vorderaar Canton de Berne Province</span></span><span style="font-style: italic;font-family:arial;font-size:85%;" > </span><span style=";font-family:arial;font-size:85%;" ><span style="font-style: italic;">d'Oberhasli</span>", Amsterdam 1785</span><span style=";font-family:arial;font-size:85%;" >.</span><br /><br /><span style="font-family:arial;">Today worldwide <a href="http://www.grida.no/publications/high-mountain-glaciers/">glaciers were studied and monitored as climate proxies</a>, and the recent measurements show that almost all of them are retreating fast. The story about glaciers, their influence on the landscape and their possible use to reconstruct </span><span style="font-family:arial;">and monitor climate is an intriguing one, with many triumphs, setbacks and changes of mind.</span> <span style="font-family:arial;"><br /><br />For centuries, if not even millennia, the high altitude belt of mountain ranges were a region visited and travelled by man, however also haunted and forbidding places.</span> <span style="font-family:arial;">The glaciers, masses of ice enclosing peaks and extending their tongues into valleys, were considered the residence of mountain spirits, then during the medieval times the priso</span><span style="font-family:arial;">n of damned souls (the Italian poet Dante Alighieri 1265-1321 imagined the centre of hell as a frozen</span><span style="font-family:arial;"> wasteland) and the playground of demons, who from time to time send avalanches and debris flows into </span><span style="font-family:arial;">the valley. </span> <span style="font-family:arial;"><br />Despite these myths there was some early insights of what glaciers actually really are made, the Greek historian and geographer Strabo (63 - 23) describes a voyages trough the Alps during the reign of Augustus and mentions<br /><br /><span style="font-style: italic;">"…there is no protection against the large quantities o</span></span><span style="font-family:arial;"><span style="font-style: italic;">f snow falling, and that form the most superficial layers of a glacier…[]. It's a common knowledge that a glacier is composed by many different layers lying horizontally, as the snow when falling and accumulating becomes hard and crystallises...[]."</span><br /><br />However the knowledge got lost, and was only rediscovered during the Renaissance. Leonardo da Vinci´s (1452-1519) is considered one of the greatest Renaissance-geniuses, </span><span style="font-family:arial;">he studied anatomy, biology and geology, however regarding the glaciers of the Alps his ideas were somehow confu</span><span style="font-family:arial;">sed, the thought glaciers were formed by not melted hail accumulating through the summer. But soon the study of nature experiences an incredible raise, and glaciers find place in various descriptions of trave</span><span style="font-family:arial;">lling scholars.<br /><br />Between 1538 and 1548 glaciers were labelled (even if not depicted) with the term "<span style="font-style: italic;">Gletscher</span>" on topographic maps of Switzerland. In his account on the Swiss land t</span><span style="font-family:arial;">he Theologian Josias Simler in 1574 describes the Rhone-glacier.<br />The first historic depiction of a glacier is considered the watercolour-paint of</span><span style="font-family:arial;"> the Vernagtferner in the Ötztaler Alps from 1601. The Vernagtferner was a glacier that repeatedly dammed up the Rofen-lake (named after the Rofen-valley), which outbursts caused heavy damage and loss of property, particularly in the years 1600, 1678, 1680, 1773, 1845, 1847 and 1848.<br /></span> <span style="font-family:arial;">In 1642 the Swiss editor Matthaeus Merian the Older in his "<span style="font-style: italic;">Topographie Helvetiae, Rhaetiae et Valesiae</span>" published various copper engravings of glaciers, and in 1706 Johann Heinrich Hottinger is int</span><span style="font-family:arial;">erested to explain the motion of "<span style="font-style: italic;">the mountains of ice</span>" in his "<span style="font-style: italic;">Descriptio Montium Glacialium Helveticorum.</span>"<br /><a href="http://historyofgeology.blogspot.com/2010/10/dragons-and-geology.html">Johann Jakob Scheuchzer</a>, visiting in the year 1705 the Rhône Glacier, published his observations of t</span><span style="font-family:arial;">he "<span style="font-style: italic;">true nature of the springs of the river Rhône</span>" in the opus "<span style="font-style: italic;">Itinera per Helvetiae alpinas regiones facta annis 1702-1711</span>", and confirms the idea that glaciers are formed by the</span><span style="font-family:arial;"> accumulation of snow and they move and flow.<br /><br /></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS89OG-gluhHyEkGs-11YB2KBSSmABNpClBUpuH31IEy2EDO15bkZIHWSIKCBkpsE0JsNBtTEpyXkXe0P7Fp6CMcgCZe2EPXEyn8brcZdDPFPca6sBaLtGEv7ZgZyew-VNfuCqiI_HwCAi/s1600/SCHEUCHZER_1708_Itinera_alpine_Glacier.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 272px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS89OG-gluhHyEkGs-11YB2KBSSmABNpClBUpuH31IEy2EDO15bkZIHWSIKCBkpsE0JsNBtTEpyXkXe0P7Fp6CMcgCZe2EPXEyn8brcZdDPFPca6sBaLtGEv7ZgZyew-VNfuCqiI_HwCAi/s400/SCHEUCHZER_1708_Itinera_alpine_Glacier.jpg" alt="" id="BLOGGER_PHOTO_ID_5553173760607790066" border="0" /></a><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.2.</span> The d</span><span style=";font-family:arial;font-size:85%;" >escription of the Rhone glacier according to Scheuchzer´s "<span style="font-style: italic;">Itinera per Helvetiae alpinas regiones facta annis 1702-1711</span>", the engraving shows the "<span style="font-style: italic;">false springs at the mountain Furca</span>" (M, N, O - left and right of the picture) and the "<span style="font-style: italic;">true springs</span>" (J, K, L) coming from the snout of the "<span style="font-style: italic;">great glacier</span>" (A-F), surrounded by the "<span style="font-style: italic;">small glacier</span>" (G, H).</span><span style="font-size:85%;"> </span><br /><br /><span style="font-family:arial;">The increasing interest to study glaciers in the Alps is also encouraged by enthusiastic travel reports; in his "<span style="font-style: italic;">Voyage pittoresq</span></span><span style="font-family:arial;"><span style="font-style: italic;">ue aux glaciers</span>" the A.C. Bordier of 1773 describes the Bosson glacier as a "<span style="font-style: italic;">huge marble ruins of a devastated city</span>".</span><br /><span style="font-family:arial;">The naturalist Horace Benedict de Saussure (1740-1799) is fascinated by the mountains of his homeland, he climbed mountains around Geneva since 1758, a</span><span style="font-family:arial;">nd after 1760 he travelled more than 14 times trough the Alps (co</span><span style="font-family:arial;">nsidering the possibilities in this time an extraordinary achievement). Between 1767 to 1779 the first volume of his "<span style="font-style: italic;">Voyages dans les Alpes</span>" is published, were he reassumes his observations and theories about the visited glaciers, he recognized moraines and large boulders as the debris accumulated by the glacier tongue and proposes to map them to interfere the former extent of glaciers. Despite this exact statement, de Saussure failed to connect large boulders found in the foreland of the mountains to the glaciers of the Alps. He assumed that these rocks were transported on their recent locations by an immense flood. That seemed to explain why most of the boulders found scattered around the plains of Germany came in first place from the regions of Scandinavia, wher</span><span style="font-family:arial;">e the same lithology where found in the crystalline continental basement, like Prec</span><span style="font-family:arial;">ambrian metamorphic rocks and paleozoic sediments. The t</span><span style="font-family:arial;">heory worked lesser to explain the foreland Alpine rocks - to transport boulders from the Alps the flood at least had to reach 1000 of meters.<br />The idea of a flood as the explanation for "glacial" deposits became largely accepted, it seemed to fit the description of the biblical flood; even Lyell and Darwin assumed that huge erratic boulders were transported by swimming ice drafts on top of a flood wave.</span><br /><span style="font-family:arial;">That glaciers could propagate far out of their valleys was however not an unusual idea for local inhabitants, who observed and experienced the growth and recess of glaciers. In academic circle this approach was a little more difficult.<br /></span> <span style="font-family:arial;">A contest thought to demonstrate the former extension of Swiss glaciers initiated by the Swiss pastor Jakob Samuel Wyttenbach in 1781 (maybe inspired be the advance of the Alpine glacier in 1770) didn't arise any interest.</span><br /><br /><span style="font-style: italic;font-family:arial;" >"Could it be proven to</span><span style="font-style: italic;font-family:arial;" > ourselves on the available documentation that both by th</span><span style="font-style: italic;font-family:arial;" >e progress of our ice mo</span><span style="font-style: italic;font-family:arial;" >untains as by our misbehaviour once for pasture most suitable land is currently covered by ice…[]"</span><br /><br /><span style="font-family:arial;">There were only careful speculations considering a former expansion of glacier: the geologists James Hutton (1726-1797) and his friend John Playfair (1748-1819) speculated about glaciations of the northern hemisphere. In 1826 a publication by the Danish mineralogist and mountain climber Jens Esmark (1763-1839) was translated into English, in this paper Jesmark discussed the possibilities that glaciers where much greater in the past then today. J.D. Forbes and Robert Jameson (who were the geology professors of Charles Darwin at Edinburgh University, Darwin in his autobiography of 1876 remembers "<span style="font-style: italic;">The sole effect they produced on me was the determination never as long as I lived to read a book on Geology or in any way to study the science.</span></span><span style="font-family:arial;">") discussed glacial theories during their lectures. And even Buckland, who still in 1831 argued "<span style="font-style: italic;">northern region of the earth seems</span></span><span style="font-style: italic;font-family:arial;" > to have undergone successive change</span><span style="font-family:arial;"><span style="font-style: italic;">s from heat to cold</span>", in 1837 was converted to <a href="http://historyofgeology.blogspot.com/2010/08/geology-history-in-caricatures-lyells.html">Lyell's uniformatism</a> and considered that sudden changes, like an ice age and glacier expansion, simply don't happen in geology.<br /><br /></span><span style="font-family:arial;">In 1815 Jean Pierre Perraudin, a chamois hunter in the Val de Bagnes, told to the engineer Ignatz Venetz </span><span style="font-family:arial;">his theory that the glaciers once covered the entire valley, and Venetz mapped features that made him even recognize that once the entire Swiss was covered by ice. Vernetz´s lecture on the assembly of the Swiss association for natural history in 1829 found little interest, only Jean de Charpentier, director of the salt mine in the city of Bex (Western Swiss), who 14 years earlier had meet and discussed with Perraudin, this time accepted and got interested in this theory.<br />He begun a detailed mapping project, and in 1834 Charpentier present</span><span style="font-family:arial;">ed again before the Swiss association the results of his investigations, but the flood theory had still much supporter. One of the critics in the public was a former stu</span><span style="font-family:arial;">dent of Charpentier, named <a href="http://historyofgeology.blogspot.com/2010/05/jean-louis-rodolphe-agassiz-28-may-1807.html">Jean L</a></span><span style="font-family:arial;"><a href="http://historyofgeology.blogspot.com/2010/05/jean-louis-rodolphe-agassiz-28-may-1807.html">ouis Rodolphe Agassiz</a>, respected palaeontologist by the establishment. Charpentier invited Agassiz to visit the city of Bex and surrounding mountains, and to observe glaciers.<br /></span><span style="font-family:arial;">In the following year (1837) Agassiz held an enthusiastic lecture about glaciers, ice ages and ice shields, and in 1840 published a detailed study of modern glaciers, their deposits and their spurs in his "<span style="font-style: italic;">Etudes sur les glaciers.</span>"<br />Agassiz experienced the same scepticism as many other ice-age proponents before.</span><br /><br /><span style="font-style: italic;">"</span><span style="font-style: italic;font-family:arial;" >I think that you should concentrate your moral and also your pecuniary strength upon this beautiful work on fossil fishes .... In accepting considerable sums</span><span style="font-family:arial;"><span style="font-style: italic;"> from England, you have, so to speak, contracted obligations to be met only by completing a work which will be at once a monument to your own glory and a landmark in the history of science ...[ ]...No more ice, not much of echinoderms, plenty of fish..."</span><br /></span><span style="font-family:arial;">Alexande</span><span style="font-family:arial;">r von Humboldt in a le</span><span style="font-family:arial;">tter to Agassiz on 2. December 1837</span> <span style="font-family:arial;"><br /><br />However Agassiz had good connections to the most important geologist of his time. Soon he could persuade William Buckland </span><span style="font-family:arial;">and later Charles Lyell.</span> <span style="font-family:arial;">After that the most respected geologist gets convinced, the rest, as always, is history:</span><br /><br /><span style="font-style: italic;font-family:arial;" >"advice - never try & persuade ye world of a new theory - persuade 2 or 3 of ye tip top men - & ye rest will go with ye stream, as Dr B. did with Sir H. Davy and Dr. Wollaston in case of Kirkdale Cave" </span> <span style="font-family:arial;"><br />Edward Jackson, about an advice given by his professor Buckland in 1832<br /><br /></span> <span style="font-family:arial;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyJOgNhNhlfYqFNnKdR3zfEYnvQzujxUbgPyYARLS3gV-nxhwVZAzSR3QIsKJcSn37nMqRpVoEmvArKpsI7MUurdNqcyZw0oX5gQsuXnadfZL092aVYn3_ba25vVl22i0UOWdgVwXzld2G/s1600/COLLOMB_1847_Glacier_Amarin.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 287px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyJOgNhNhlfYqFNnKdR3zfEYnvQzujxUbgPyYARLS3gV-nxhwVZAzSR3QIsKJcSn37nMqRpVoEmvArKpsI7MUurdNqcyZw0oX5gQsuXnadfZL092aVYn3_ba25vVl22i0UOWdgVwXzld2G/s400/COLLOMB_1847_Glacier_Amarin.jpg" alt="" id="BLOGGER_PHOTO_ID_5553172695942543106" border="0" /></a><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span><span style="font-style: italic;"> </span>Reconstruction of the glacier that filled the valley of St. Amarin (southern Vosges, France), probably the first tentative reconstruction of an ice age glacier - from COLLOMB (1847): <span style="font-style: italic;">"<a href="http://books.google.at/books?id=8usTAAAAQAAJ&dq=Preuves+de+l%C2%B4existence+d%C2%B4anciens+glaciers+dans+les+vall%C3%A9es+des+Vosges.&printsec=frontcover&source=bl&ots=xxsyfU9e3p&sig=TC6r01QvB3Dk-dDI7cfW4noQziI&hl=de&ei=3NPsSeT1BdKKsAaXqIGhBw&sa=X&oi=book_result&ct=result&resnum=6">Preuves de l´existence d´anciens glaciers dans les vallées des Vosges.</a></span></span></span><span style="font-size:85%;"><span style="font-style: italic;">"</span></span><br /><br /><span style="font-family:arial;">Agassiz research on the Unteraar-glacier established the foundations of glaciology; he recorded</span><span style="font-family:arial;"> the dimension of the glacier, his velocity and even ventured inside the glacier by passing trough a glacial mill. </span> <span style="font-family:arial;">Soon after 1</span><span style="font-family:arial;">850 the measurements methods introduced by Agassiz were carried out on various glaciers of the Alps and repeated nearly every year.<br /><br /></span><span style="font-family:arial;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbhv9WpRcZobMW6SNE_GvsSd6RLNzU8D65x3Nc34cV7YiL604AwHfhXMxLin21rjMlfZecGJa0S-5YJWf2jv8nXnC1LuQopLzjeAuGnBV8DuSW45aOfb_maFuLzyaA6GrclKK_dfd4B9JQ/s1600/SCHMETZER_1891_Glacier_Hintereis.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 278px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbhv9WpRcZobMW6SNE_GvsSd6RLNzU8D65x3Nc34cV7YiL604AwHfhXMxLin21rjMlfZecGJa0S-5YJWf2jv8nXnC1LuQopLzjeAuGnBV8DuSW45aOfb_maFuLzyaA6GrclKK_dfd4B9JQ/s400/SCHMETZER_1891_Glacier_Hintereis.jpg" alt="" id="BLOGGER_PHOTO_ID_5553172300303127458" border="0" /></a></span><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.4.</span> The Hintereis-glacier (in the centre of the picture), Hochjoch-glacier (left) and the Kesselwand- glacier, drawing by Schmetzer 1891, the Hintereis-glacier is one of the glacier with the longest active monitoring program, values about his length change reach back to 1848, since then the glacier lost 3km of his tongue.</span><span style="font-size:85%;"><br /></span><span style=";font-family:arial;font-size:85%;" >"<span style="font-style: italic;">Aus den tiroler Alpen: Der Abschluß des Oetzthales mit dem Hochjochgletscher (</span></span><span style=";font-family:arial;font-size:85%;" ><span style="font-style: italic;">links), dem Hintereisferner (in der Mitte) und dem Kesselwandferner (rechts oben). Nach der Natur gezeichnet von K. Schmetzer (1891).</span>"</span><br /><span style="font-family:arial;"><br />These records showed various fluctuations, but from 1850 onward a general trend of recession of glaciers in the Alps is observable. This trend has experienced a strong increase in the last 50 years, causing concern for the fast change in the landscape, the destabilisation of the rock walls once supported by the melting glaciers and the alteration of the discharge and hydrology of mountain ranges.</span><br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRDh5WhOflJeNPuystkXZrE5OUqzoXBDcwSFDiq39OzFEiA58Mypr8qWvl-kiMHBZFQ5mbbX0CJURfa8foSCZj0lvBrGkCH6CmwW-wtZZhN6jx0HO1fnZ5yaT5ZkoBdWp7o-htIvNwNece/s1600/BRESSAN_2010_Glacier.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 391px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRDh5WhOflJeNPuystkXZrE5OUqzoXBDcwSFDiq39OzFEiA58Mypr8qWvl-kiMHBZFQ5mbbX0CJURfa8foSCZj0lvBrGkCH6CmwW-wtZZhN6jx0HO1fnZ5yaT5ZkoBdWp7o-htIvNwNece/s400/BRESSAN_2010_Glacier.jpg" alt="" id="BLOGGER_PHOTO_ID_5553171673725666386" border="0" /></a><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-weight: bold;">Fig.5.</span> Temperature rise in the Alps and length loss of the glaciers of the Ötztaler Alps (western Austria) in the period 1900-2010. The valley glaciers with their tongues extending in the valleys showed the strongest retreat and degradation of the studied Austrian glaciers</span>.</span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com3tag:blogger.com,1999:blog-7510048715512322715.post-58914160077884493222010-06-26T10:17:00.000-07:002010-06-26T13:13:30.018-07:00Geology and Cyclicity: Milankovitch´s idea<div style="text-align: justify;"><span style="font-style: italic;font-size:100%;" ><span style="font-family:arial;">"I do not think that's my duty to teach to the ignorant the most basic things, and I have never forced anyone to accept my theory, on so far nobody could expose something.</span></span><span style="font-style: italic;">"</span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">Milutin Milankovitch in 1950</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">Milutin Milankovitch (1879 - 1958) was born in a relatively wealthy Serbian family, so it was almost a kind of obligation for him to archive a higher education degree and later take over the family business. So he studied agriculture, but following a passion for natural sciences he went to Vienna, where he in 1904 concluded his studies as an engineer.<br />Five years later he returned to Belgrad where he found employment as professor for mathematical studies at the University. </span></span> <span style="font-size:100%;"><span style="font-family:arial;">Like Croll he was in search of a scientific problem worth his efforts, and in 1911, sharing some presumably good wine with a friend, he decided to develop a mathematical theory to explain climate changes on the planets of the solar system.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">He studied the <a href="http://rockglacier.blogspot.com/2010/06/geology-and-cyclicity.html">work of Croll</a>, recognized his previous achievements but also noted his insufficient data. Milankovitch also consulted the work of the German mathematician Ludwig Pilgrim, who in 1904 published exact calculations of the orbital eccentricity, earth's obliquity and the rotation of the axis of earth (change of the perihelion). Pilgrim also tried to correlate the eccentricity with the occurrence of ice ages.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />Between 1912 and the beginning of World War I Milankovitch published some preliminary abstracts of his developing theory, concluding that all three factors, in contrast to previous authors, are important to explain earth's climate. At the beginning of the War, Milankovitch was arrested as Serbian officer and imprisoned in his hometown Daly, but fortunately he was carrying with him his work, and so even in the first night as prisoner he continued to work. "<span style="font-style: italic;">When after midnight I looked around in the room, I needed some time to realize where I was. The small room seemed to me like an accommodation for one night during my voyage in the Universe.</span>"<br />Soon after he was released and travelled back to Belgrad, where he continued his work during the entire War and published some ideas about the climate of Mars and Venus.</span></span><br /><br /><span style="font-family:arial;">Finally he published his theory in 1920 "<span style="font-weight: bold;">Mathematische Theorie der durch Sonneneinstrahlung ausgelösten Wärmephänomene</span>" (Mathematical theory of thermal phenomena caused by solar radiation).</span></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /></span></span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://3.bp.blogspot.com/_tGHzOEp3UKA/TCY1H7ObxQI/AAAAAAAABfM/n_rPceG0HKc/s1600/BRESSAN_Milankovitch_Cycles.jpg"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"></span></span></span></span></span></span></span></span></a><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjChzE8vx6zQtpmQSxDghyU_La715tq6vkfYgnvnjAPUmaZd26sqM5dAjoGE3wpnckUoUmq0KlUbCbxxZxdGaJLdFeegKqBV53yCUhq5jLxK7CASldPZ52yPdZByXHlhJusodbdeJSubbw/s1600/BRESSAN_Milankovitch_Cycles.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 202px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjChzE8vx6zQtpmQSxDghyU_La715tq6vkfYgnvnjAPUmaZd26sqM5dAjoGE3wpnckUoUmq0KlUbCbxxZxdGaJLdFeegKqBV53yCUhq5jLxK7CASldPZ52yPdZByXHlhJusodbdeJSubbw/s400/BRESSAN_Milankovitch_Cycles.jpg" alt="" id="BLOGGER_PHOTO_ID_5487177925252438930" border="0" /></a></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.1.</span> Variations in the Earth's orbital parameters:</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />1. Eccentricity: the shape of the orbit around the sun.</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />2. Changes in obliquity: changes in the angle that Earth's axis makes with the plane of Earth's orbit.</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />3. Precession: the change in the direction of the Earth's axis of rotation, i.e., the axis of rotation behaves like the spin axis of a top that is winding down; hence it traces a circle on the celestial sphere over a period of time. </span></span> <span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><br />Together, the periods of these orbital motions have become known as Milankovitch cycles. These parameters influence the amount of solar energy on earth´s surface, especially during summer of the northern hemisphere (55°-65°N).</span><br /><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">In his theory he postulated:</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />- Glaciations are caused by variations of astronomical parameters </span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />- The parameters influence the amount of solar energy on earth´s surface, especially during summer of the northern hemisphere (55°-65°N)</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />- It is possible to calculate these changes, and so calculate the climate in the past.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />The German meteorologists Wladimir Köppen and Alfred Wegener supported the new theory, and noted the apparent coincidence of the calculated curve with the by Penck and Brückner postulated four European glaciations.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAEKdI2vwrLPDORHGG29jj9Go2Cs_rZgCURDSbvcnbbtuifkJva1hCgSrmPJjjMX8trZEWgnt1qlCRd0BGzn7Dmu-8pSFkhzKBtJfkGghcscHOm0i013q8t0zQtDm3_tlEktejQOA6mB_7/s1600/KOEPPENetal_1924_Klima_geologische_Vorzeit.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 232px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAEKdI2vwrLPDORHGG29jj9Go2Cs_rZgCURDSbvcnbbtuifkJva1hCgSrmPJjjMX8trZEWgnt1qlCRd0BGzn7Dmu-8pSFkhzKBtJfkGghcscHOm0i013q8t0zQtDm3_tlEktejQOA6mB_7/s400/KOEPPENetal_1924_Klima_geologische_Vorzeit.jpg" alt="" id="BLOGGER_PHOTO_ID_5487128966921442338" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-weight: bold;">Fig. 2.</span> Figure from KÖPPEN & WEGENER 1924, where they correlated the calculated cycles to the know ice ages at that time.</span><br /><br /></span></span> <span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaaamfWXWhu_v-RL88zm2wyc7wZgIrAgOi0YVYEZ9xFbG3zdcNLdC0KWuIj6_wrpFN-z4t45dnkCT8_POxXds19oF3og1eZ9DzznDWqgnIhq0vEvsQKZgmzdnTsEPso60QeXxda3V84SIx/s1600/BRESSAN_Capo_Spartivento.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaaamfWXWhu_v-RL88zm2wyc7wZgIrAgOi0YVYEZ9xFbG3zdcNLdC0KWuIj6_wrpFN-z4t45dnkCT8_POxXds19oF3og1eZ9DzznDWqgnIhq0vEvsQKZgmzdnTsEPso60QeXxda3V84SIx/s400/BRESSAN_Capo_Spartivento.jpg" alt="" id="BLOGGER_PHOTO_ID_5487128590679369426" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span> Outcrop of the Trubi-Formation at Capo Spartivento (South-Italy), a succession of Globigerina-marls from the Pliocene-Pleistocene transition. The regular stripes are caused by organic rich layers, thought to be caused by changes in the biological productivity in response of changes of the astronomical parameters - the Milankovitch cycles</span></span></span><span style="font-size:85%;">.</span><br /><br /><span style="font-size:85%;"><span style="font-family:arial;">References:</span><br /><br /></span><span style="font-size:85%;"><span style="font-family:arial;">CHORLTON, W. (ed) (1985): Ice Ages (Planet Earth). Time-Life Books: 176</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />KÖPPEN, W. & WEGENER, A. (1924): Die Klimate der geologischen Vorzeit. Borntraeger, Berlin: 256</span><br /><br /></span><span style="font-size:85%;"><span style="font-family:arial;">Resources:<br /><br /></span></span><span style="font-size:85%;"><span style="font-family:arial;">NASA Earth Observatory: <a href="http://earthobservatory.nasa.gov/Features/Milankovitch/">Milutin Milankovitch (1879 - 1958)</a>. Accessed 26.06.2010 </span></span> </div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-64886023044640369422010-06-06T09:11:00.000-07:002010-06-26T10:25:23.723-07:00Geology and Cyclicity<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">1842, 5 years after Agassiz's "<span style="font-style: italic;">Discourse of Neuchatel</span>", the French mathematician Joseph Alphonse Adhémar elaborated a hypothesis to explain a cyclic occurring of ice ages. He calculated the variations of the "direction" and declination of earth axis and the "movements" of earth around the sun during the geological past.<br />These cyclic factors influence the time and the energy density of solar radiation that reach earth from sun, causing cyclic climatic change.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">Adhémar proposed that in a period of 11.000 years the hemisphere that experiences a longer winter, resulting from these three astronomical factors, would develop in an ice age.<br />But in 1852 Alexander von Humboldt noted that Adhémar didn't consider an important factor in his calculations, even if one hemisphere experience lower radiation, the opposite hemisphere experience an increase, so in the end the total sum remains more or less identical.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">Nevertheless the idea of the French mathematician was intriguing, and would influence later researchers.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">In 1833, James Croll (1821-1890), son of a poor stonecutter of Perthshire, purchased a copy of the "<span style="font-style: italic;">Penny Magazine</span>", a magazine for children education. He was fascinated and began extensively to read, and some time later acquired he's first books dealing with natural science; "<span style="font-style: italic;">At first I was totally confused, but then the beauty and simplicity of the ideas provided me with delight and surprise, and I began seriously to study the matter</span>."</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />Croll had no easy living in the next 20 years; he travelled the country, most time working as casual labourer, and in 1850 managed (for a brief time) the only Scottish pub were no alcohol was allowed.<br />He then found work as a maintenance supervisor of the Andersonian College in Glasgow, where he had access to the library and the hosted scientific works, a knowledge resource that he grateful exploited.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />"<span style="font-style: italic;">At that time, the question of what could have triggered the ice age was much discussed among geologists. So in the spring of 1864, I directed my attention to this topic.</span>"</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />From 1864, Croll corresponded with Sir Charles Lyell, on links between ice ages and variations in the Earth's orbit. This led to a position in the Edinburgh office of the Geological Survey of Scotland, as keeper of maps and correspondence, where the director, Sir Archibald Geikie, encouraged his research. He also corresponded with Charles Darwin on erosion by rivers.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />Croll, based on observations of the astronom Urbain Jean Josef Leverrier, used in his calculations an important factor that Adhémar did not know, the "movements" of the perihelion and aphelion on earth's ecliptic (precession of the equinoxes). He published his research in the book "<span style="font-weight: bold;">Climate and Time, in Their Geological Relations</span>" in 1875.</span></span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMLxqAkDT9lxSbMjzsKyqpW5MI_kb1MhaarDfq8uH9OoiFTi7-xIJaQEIfRd-kuw-qqFLd9Cyx3lzD4uSFtsBDZEi6YxzowJDbENSUw03rzlJpvZw_gdwipZqP-O9GTxTpDJQWyT1kIugS/s1600/CROLL_1875_1.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 245px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMLxqAkDT9lxSbMjzsKyqpW5MI_kb1MhaarDfq8uH9OoiFTi7-xIJaQEIfRd-kuw-qqFLd9Cyx3lzD4uSFtsBDZEi6YxzowJDbENSUw03rzlJpvZw_gdwipZqP-O9GTxTpDJQWyT1kIugS/s400/CROLL_1875_1.jpg" alt="" id="BLOGGER_PHOTO_ID_5479691268639275554" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> Glacial and interglacial conditions when eccentricity is at its superior limit, from CROLL1875, frontispiece (from FLEMING 2006).</span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNWuP6hVEpby-7xcTDn-jKYxVsCL0Tt13QtxdMawaGWLsWZP5_79_zPh1e9mZF5yryzvq5xgsCiE3vPhsR4pnmcqE0w2LQDu9MULZv3NojXnvBkQFGqsqRg_kQiH3ZEl1YH7dRQp5a0nZI/s1600/CROLL_1875_2.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 200px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNWuP6hVEpby-7xcTDn-jKYxVsCL0Tt13QtxdMawaGWLsWZP5_79_zPh1e9mZF5yryzvq5xgsCiE3vPhsR4pnmcqE0w2LQDu9MULZv3NojXnvBkQFGqsqRg_kQiH3ZEl1YH7dRQp5a0nZI/s400/CROLL_1875_2.jpg" alt="" id="BLOGGER_PHOTO_ID_5479691133257081602" border="0" /></a></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2</span>. Variations in the earth's orbit for three million years before 1800 A.D. and one million years after it, from CROLL 1875, following p. 312 (from FLEMING 2006).</span><br /><br />Geikie wrote about the work of Croll: "<span style="font-style: italic;">The astronomical theory seems to me the best solution to the present ice age riddle. It bears in it all the decisive factors for the occurrence of alternating cold and warm periods, and accounts for the peculiar character of glacial and interglacial climates.</span>"</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />But there was a problem, even if dating methods at these times were only approximate, geological evidences supported a very young age of glacial deposits, but after Croll´s theory the last glacial period had ended 80.000 years ago. When Croll died, highly respected, geologists considered his theory wrong.<br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">Geikie resumed: "<span style="font-style: italic;">It may well be, that with certain modifications of his views; one day we will solve the secret. But for now we must be continue to work and wait.</span>"</span><span style="font-family:arial;"><br /><br />The modifications as hoped by Geikie will come only years later, and a glass wine will be the first step to solve the problem of the cyclicity of glacial periods: </span><a href="http://rockglacier.blogspot.com/2010/06/geology-and-cyclicity-milankovitchs.html"><span style="font-family: arial;">Geology and Cyclicity: Milankovitch´s idea.</span></a></span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivjYNzUZJpmhNIsbfBRxT41nGGzkR3Wf3gSHy9SyVNGPLuDpVsmnYdw53i-P6in4vv6hP3C19HLszKqzu01ZstG5mgsT_9yQ77_4gn1VlsNEpu4CSJTgskbDn8mY8oXNwuV2hUo8-PWSnO/s1600/BRESSAN_ScalaTurchi_Rossello.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 319px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivjYNzUZJpmhNIsbfBRxT41nGGzkR3Wf3gSHy9SyVNGPLuDpVsmnYdw53i-P6in4vv6hP3C19HLszKqzu01ZstG5mgsT_9yQ77_4gn1VlsNEpu4CSJTgskbDn8mY8oXNwuV2hUo8-PWSnO/s400/BRESSAN_ScalaTurchi_Rossello.jpg" alt="" id="BLOGGER_PHOTO_ID_5479689802479948354" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.3.</span> Orbitally forced cyclic sedimentation in the Trubi Formation of Zanclean age at Scala</span></span><span style="font-size:85%;"><span style="font-family:arial;"> dei Turchi, in the Rossello composite section (Sicily), that represents the template for the</span></span><span style="font-size:85%;"><span style="font-family:arial;"> Pliocene Series.</span></span><br /><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEloBn4uzfTiMIvfRUmm7LGIMJhAnRvk_eN37_RfAWokF9gxo3jERk2DXHvFMFQ_JZ_eEHvwdWRHxDySwTrUKTSSlUfPamOGtLXsh0KYmcZehDdc_budtQChSbcbew6itNwztk09PhBEXZ/s1600/BRESSAN_PuntaPiccola.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEloBn4uzfTiMIvfRUmm7LGIMJhAnRvk_eN37_RfAWokF9gxo3jERk2DXHvFMFQ_JZ_eEHvwdWRHxDySwTrUKTSSlUfPamOGtLXsh0KYmcZehDdc_budtQChSbcbew6itNwztk09PhBEXZ/s400/BRESSAN_PuntaPiccola.jpg" alt="" id="BLOGGER_PHOTO_ID_5479689515369792642" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.4.</span> Orbitally forced cyclic sedimentation as expressed in the uppermost part of the Trubi Formation and in the overlying Monte Narbone Formation at Punta Piccola (Sicily), where the Piacenzian GSSP has been defined.</span></span></span><br /><br /></div> <span style="font-size:85%;"><span style="font-family:arial;">References:</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br /><br />CHORLTON, W. (ed) (1985): Ice Ages (Planet Earth). Time-Life Books: 176</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />CROLL, J. (1875): <a href="http://www.archive.org/details/climateandtimei00crolgoog">Climate and Time, in their Geological Relations.</a> A theory of secular changes of the Earth's Climate. D. Appleton and Company, New York: 630</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />FLEMING, J.R. (2006): <a href="http://www.meteohistory.org/2006historyofmeteorology3/3fleming_croll.pdf">James Croll in Context</a><a href="http://www.meteohistory.org/2006historyofmeteorology3/3fleming_croll.pdf">:</a> The Encounter between Climate Dynamics and Geology in the Second Half of the Nineteenth Century. History of Meterology 3: 43 - 54</span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com1tag:blogger.com,1999:blog-7510048715512322715.post-36857049931023492152010-05-24T09:08:00.000-07:002010-05-24T09:12:21.192-07:00Megafauna Methane collapse<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">There are <a href="http://rockglacier.blogspot.com/2010/01/did-volcanoes-kill-mammoth.html">lots of hypothesis</a> dealing with the extinction of the Pleistocene Megafauna. Now a research team of the University of New Mexico in Albuquerque adds a something different approach to the problem of climate change as extinction cause. SMITH et al. published a paper where they compared the production of methane of modern farm animals to extinct herbivores. Methane is a very effective green house gas. The research team observed in the geological record strong variations of the concentration of methane between the last glacial maximum, 18.000 years ago, and the Younger Dryas (13.000 years ago). Especially at the beginning of the temperature drop of the Younger Dryas the concentration of methane diminished considerable fast. The research team speculates that with the beginning extinction of large herbivores an important source of methane was removed from the climate system, destabilizing climate and environment end enforcing the extinction rate. The fast changes observed, faster than previously known variations, maybe are also related to human activity, disproving precedent r<a href="http://rockglacier.blogspot.com/2009/11/extinctions-excrements.html">esearch that excluded humans</a> as triggers for the Pleistocene extinction.</span></span><br /><br /><span style=";font-family:arial;font-size:85%;" >References</span><span style="font-size:85%;"><br /><br /></span><span style=";font-family:arial;font-size:85%;" >SMITH, F.A.; ELLIOTT, S.M.. & YONS, K. (2010): <a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo877.html">Methane emissions from extinct megafauna.</a> Nature Geoscience. Published online: 23. May 2010: doi:10.1038/ngeo877</span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-9453624448031325212010-05-24T06:36:00.000-07:002010-05-24T09:19:13.277-07:00The hard life of being geologist - An introduction<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">150 years ago the practical work of geologists in the field was considerable different to modern standards (at least in Europe), there were differences in the equipment, but also differences in the circumstances of exploring and mapping the area of interest. </span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />These differences begins even how to reach a specific area, today with cars most regions are accessible, 100 years ago geologists used when possible the first established train connections, but most localities were only to approach with carriages or by walking.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />Because these voyages were expensive, geologist used to save time and money and after arrival in the designated study area stayed in the field for months during the entire summer.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">To map a larger area, most time early geologists established a base camp where heavy equipment was stored. From this base camp they started in the field, sometimes for days, sleeping in farms, cottages or under the sky.<br /><br />It was a very physical work, for example the Austrian geologist Marcus Vinzenz Lipold mapped in 1853 in only one day the area surrounding the Großglockner (3.797m), and starting from the village of Ferleiten (1.151m), reached the Erzherzog-Johann-Hütte (3.454m), and finally descended back to the village of Heiligenblut (1.188m) - a heigth difference of 2.700m and a linear dist</span></span><span style="font-family:arial;">ance of 28 kilometres.</span> <span style="font-family:arial;"><br /><br />Every geologist of the Austrian Geological Survey carried during field exploration the standard equipment: maps and a plate to draw on with a tripod, two barometers, pocket-compass, a common telescope and a telescope with incorporated compass, psychrometer (a tool to determinate the humidity of air), thermometer and a camera obscura (an ancestor of modern digital cameras). To these tools we have to add hammers of various sizes and a portable drill.</span><br /></div><div style="text-align: justify;"><span style="font-family:arial;"><br /></span><div style="text-align: center;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilSZkmK_EcsJ9WKdRuln8KKVaNRCNM6zk8-Qa9nnqsNVyY-4HZ22Ski6HCcIt4oyY0vxD9mSL38AcIejjPkyhszExAdN1pTVotrr5ygM2HtDtGQbfiL7V9o4KZdOg6y_TGP8NpuMHtb5jn/s1600/Geognost_1800.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 321px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilSZkmK_EcsJ9WKdRuln8KKVaNRCNM6zk8-Qa9nnqsNVyY-4HZ22Ski6HCcIt4oyY0vxD9mSL38AcIejjPkyhszExAdN1pTVotrr5ygM2HtDtGQbfiL7V9o4KZdOg6y_TGP8NpuMHtb5jn/s400/Geognost_1800.jpg" alt="" id="BLOGGER_PHOTO_ID_5474826499210802994" border="0" /></a></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> "Geognosts" around 1800.</span></span><br /></div><span style="font-family:arial;"><br />The equipment underscores the broad "uses" for geologists. Because natural science wasn't yet so specialized as today, and geology itself not so clearly delimited against other scientific fields, from a geologist it was also demanded that he possess know-how in meteorology, palaeontology, mineralogy, archaeology, botany and ethnology.<br />The geologist Johann Czjzek in 1850 describes the requests to be a geologist: "<span style="font-style: italic;">To every geologist mister Wilh. Haidinger, as head of the department, recommended these instructions; not only to carry out their geological tasks, but also to collect a broad variety of minerals, rocks, fossils and measurements, if these are related to science and regional and cultural studies, especially physical, geographical, historic, archaeological and ethnographic data, which connect the fossil world with the beginnings of our own history."</span></span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /></span></span><div style="text-align: center;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkkWyRniXUgTCyTyf2eQzRD7lIWcZ54J6w8IeFd3PlrpcZ-AdRPWPchwMOi1e1Ep4g5NjWdc41UZ64Qt9DdwPu6cykVEAAos00h5YLLnIfQutgEDOUftio7NL8XGmWBP1Q9Bw8G6FlHRIP/s1600/Geologen_Wiener_Reichsanstalt.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 205px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkkWyRniXUgTCyTyf2eQzRD7lIWcZ54J6w8IeFd3PlrpcZ-AdRPWPchwMOi1e1Ep4g5NjWdc41UZ64Qt9DdwPu6cykVEAAos00h5YLLnIfQutgEDOUftio7NL8XGmWBP1Q9Bw8G6FlHRIP/s400/Geologen_Wiener_Reichsanstalt.jpg" alt="" id="BLOGGER_PHOTO_ID_5474825887745437090" border="0" /></a></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.2.</span> </span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-family:arial;">Some of the most famous geologists of the Geological Survey of Vienna (ca. 1860).</span></span></span></span><br /><br /><span style="font-size:130%;"><span style="font-family:arial;">I will post these contributions parallel on a specific created blog: <a href="http://historyofgeology.blogspot.com/">History of Geology</a>.</span></span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><br /><span style="font-size:85%;">References</span></span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br /><br />GSTÖTTNER, M. (1999): Ausrüstung und Leben der frühen Geologen im Gelände. In: Geologische Bundesanstalt (ed.), Die Geologische Bundesanstalt in Wien - 150 Jahre Geologie im Dienste Österreichs (1849-1999). Böhlau Verlag. Wien.</span></span> </div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-84346472091560127122010-05-19T12:07:00.000-07:002010-05-19T12:47:04.198-07:00Mount St. Helens: 30 years of posteruption glacier development<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrDBkJo6kaVMhbvqNwbt0oZ_JQYv8A7Fd0P2tpxU4YFD925-oe5lkL9W65o1AXTWrpVViLBJOzL1miMfCoz86ixaBKcdtSRUU2cJ3S7T-QvgZARL5YyvfgLXgHd1ZkTgbD1tImUO36iME/s1600/800px-MSH06_aerial_crater_dome_glacier_from_NW_10-22-06.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 266px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrDBkJo6kaVMhbvqNwbt0oZ_JQYv8A7Fd0P2tpxU4YFD925-oe5lkL9W65o1AXTWrpVViLBJOzL1miMfCoz86ixaBKcdtSRUU2cJ3S7T-QvgZARL5YyvfgLXgHd1ZkTgbD1tImUO36iME/s400/800px-MSH06_aerial_crater_dome_glacier_from_NW_10-22-06.jpg" alt="" id="BLOGGER_PHOTO_ID_5473060825975732370" border="0" /></a><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.1.</span> Glaciers in the crater of Mount Saint Helens. The Crater Glacier is shaped in a horseshoe around the new domes that have developed in the crater. The west lobe of the glacier is visible in the bottom right and two more rock glaciers can be seen to the left of the east lobe (from <a href="http://en.wikipedia.org/wiki/Crater_Glacier">Wikipedia</a>).</span></span><br /></div><br /><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">On May 18. 1980 Mount St. Helens landslided/exploded and lost up to 400m in height, and the geoblogosphere is celebrating the event, so must I, not necessarily focusing strictly on the gone mountain, but with a glacier related post.</span></span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><br /></span></span><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">With the explosion, most of the glaciers surrounding the 2.950m high peak got annihilated. The ice was in part disintegrated or melted and provided huge amounts of water for the <a href="http://rockglacier.blogspot.com/2008/11/volcano-ice-interactions.html">lahars</a>, a part of the ice detritus also got embedded in the hot volcanic ash and evaporating suddenly, exploded and created a cratered landscape.</span></span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCI5EUWVU1n3cglFRi38r2uSf4FSk33bXJg6xO3TmUQnwSnAb971UEelVfixvtUrLXSFCUqWxLrSgZVihEG0uirf4MiDvTDqXKhCHuo6XNWZT6bZz0atmgeqmEvjYBnG15qGvq50vs_Tk/s1600/SCHILLINGetal_2004_GlaciersStHelens_1.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 357px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCI5EUWVU1n3cglFRi38r2uSf4FSk33bXJg6xO3TmUQnwSnAb971UEelVfixvtUrLXSFCUqWxLrSgZVihEG0uirf4MiDvTDqXKhCHuo6XNWZT6bZz0atmgeqmEvjYBnG15qGvq50vs_Tk/s400/SCHILLINGetal_2004_GlaciersStHelens_1.jpg" alt="" id="BLOGGER_PHOTO_ID_5473060641979521266" border="0" /></a><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.2. </span>Mount St. Helens before the May 18, 1980, eruption, showing location and aerial extent of glaciers (modified from Brugman and Post, 1981), from SCHILLING et al. 2004.</span></span><br /><br />Prior to the eruption, 13 small glaciers with a combined surface area of about 5km2 existed on the volcano.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">From these glaciers the Loowit and Leschi glacier were completely destroyed, and the other glaciers suffered major mass lost.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />5 years after the eruption first permanents snow patches were observed in the area between the central dome and the remaining crater walls, these patches in the following years continued to grow, feed by abundant precipitations during wintertime, avalanches and the shadow of the steep walls and protection by isolating rock detritus. In 1996 a small glacier was born, and many names were proposed for it: Amphitheatre Glacier, Crater Glacier, Tulutson Glacier, Spirit Glacier and Tamanawas Glacier, finally it was decided that the youngest glacier of the United States should be named Crater Glacier.<br /><br /></span></span><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP66QGBig42Gvb-7Ajwj3znd2vzdMB69hTMg85qTSBhGSGw7RJrL6Ekh-Yx3UnvPdAkQaT9TlO31ACuwuSRzYbGri2okPS4McXp1mExZzcMUY4I9ktQ6GD0_h9MygCgZu5O74lHhFvG3I/s1600/SCHILLINGetal_2004_GlaciersStHelens_2.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 316px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP66QGBig42Gvb-7Ajwj3znd2vzdMB69hTMg85qTSBhGSGw7RJrL6Ekh-Yx3UnvPdAkQaT9TlO31ACuwuSRzYbGri2okPS4McXp1mExZzcMUY4I9ktQ6GD0_h9MygCgZu5O74lHhFvG3I/s400/SCHILLINGetal_2004_GlaciersStHelens_2.jpg" alt="" id="BLOGGER_PHOTO_ID_5473060485559935346" border="0" /></a></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.3.</span> Extent of ice on Mount St. Helens. Area in white shows location and extent of glaciers as of September 2001. Glacier area, inside the crater, is about 1 km2, whereas the glacier area outside the crater is 0.52 km2, from SCHILLING et al. 2004.</span></span><br /></div><br /><span style="font-size:100%;"><span style="font-family:arial;">Crater Glacier after 20 years of growing is today the largest of the remaining glaciers on Mount St. Helens, with an area of 1km2, thickness of 200m and a volume of 120 million m3.<br /><br />The fast development and <a href="http://rockglacier.blogspot.com/2010/03/accretionary-wedge-23-that-is-not-dead.html">young age of various small rock glaciers</a> inside the crater is also very intriguing.<br /><br /><span style="font-size:85%;">References:<br /><br />SCHILLING, S.P.; CARRARA, P.E.; THOMPSON, R.A. & IWATSUBO, E.Y. (2004): <a href="http://neogeo.kent.edu/munro/glacial/reading/Schilling_Steve_P.pdf">Posteruption glacier development within the crater of Mount St. Helens, Washington, USA.</a> Quaternary Research 61: 325-329</span><br /></span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com3tag:blogger.com,1999:blog-7510048715512322715.post-48530354604168925322010-05-17T12:31:00.000-07:002010-05-17T12:35:12.455-07:00They say that reading rocks is hard to do...<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNG_UaXo-o4eEGHoi_K_ebnHCuGZeBoBVZHMpK5WQs6zPx2WpRwYIrtBlnNBVP1qzmHu7pcvmU0foQkv-d4Kfcuq0ybeRE4BN48Iz3yJQAr5f2bpInpS79F74GOfZnc2WjDJUsLMRPtTg/s1600/Bressan_Bletterbach.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 134px; height: 200px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNG_UaXo-o4eEGHoi_K_ebnHCuGZeBoBVZHMpK5WQs6zPx2WpRwYIrtBlnNBVP1qzmHu7pcvmU0foQkv-d4Kfcuq0ybeRE4BN48Iz3yJQAr5f2bpInpS79F74GOfZnc2WjDJUsLMRPtTg/s200/Bressan_Bletterbach.jpg" alt="" id="BLOGGER_PHOTO_ID_5472324163339161346" border="0" /></a><span style="font-size:100%;"><span style="font-family: arial;">Ever wonder how to tell if a rock layer is right-side-up or turned by mountain building? Dr. Richard Alley has the answers !</span></span><br /></div><br /><br /><object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/so_-OaDCddo&hl=de_DE&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/so_-OaDCddo&hl=de_DE&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="420" height="320"></embed></object>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-51843418838635309612010-05-11T11:50:00.000-07:002010-05-15T11:43:28.232-07:00Te Pito Te Henua: Botanical Investigations from the navel of the world<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivhqqO5E99aGMPyDMTIBeom8fkJbWiAge3pHjEo3UF6TgPtWUyiXF8b7_QVla6_BenTybuRuqWvmQoEn2sebtvLhfMbq7hyphenhyphencukyVDP-ulHstVgVznI0faCiP3bzRX7ZmHrhDeI_zksbwI/s1600/Moai_Rano_raraku.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 112px; height: 149px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivhqqO5E99aGMPyDMTIBeom8fkJbWiAge3pHjEo3UF6TgPtWUyiXF8b7_QVla6_BenTybuRuqWvmQoEn2sebtvLhfMbq7hyphenhyphencukyVDP-ulHstVgVznI0faCiP3bzRX7ZmHrhDeI_zksbwI/s200/Moai_Rano_raraku.jpg" alt="" id="BLOGGER_PHOTO_ID_5470091772160063218" border="0" /></a><span style="font-family:arial;">The collapse of the civilisation on Easter Island, or Rapa Nui in the native language, became very popular with the film <a style="font-style: italic;" href="http://www.youtube.com/watch?v=mQ3kbX5jzX0">"Rapa Nui"</a> (1994) and the book of the American biologist Jared Diamond <a href="http://en.wikipedia.org/wiki/Collapse_%28book%29"><span style="font-style: italic;">"Collapse - How societies choose to fail or survive"</span></a> (2005). After the proposed reconstruction in both film and book, human population growth and overexploitation of natural resources, especially clearing of forest, caused soil degradation and resulted in diminished agriculture production, not able any more to feed the population. In the resulting famine and civil wars one of the highest developed cultures in the Pacific Ocean collapsed.</span><br /></div><div style="text-align: justify;"><span style="font-family:arial;"><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhY99tClZkl9JUrFUz-XD25Gotw8mWdlRTd4Yv0Zq42sjv2s0VIstB6U8o-HZPr3dOE-HVYpXwrts425ltWRIKFbmkOtslAbYjSpvVtvm8vHVEdl6QQCfT2-rZIKPRNjPxIYP_IG8ehZf8/s1600/THOMSON_1891_TePitoTeHenua.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 249px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhY99tClZkl9JUrFUz-XD25Gotw8mWdlRTd4Yv0Zq42sjv2s0VIstB6U8o-HZPr3dOE-HVYpXwrts425ltWRIKFbmkOtslAbYjSpvVtvm8vHVEdl6QQCfT2-rZIKPRNjPxIYP_IG8ehZf8/s400/THOMSON_1891_TePitoTeHenua.jpg" alt="" id="BLOGGER_PHOTO_ID_5470088575299765090" border="0" /></a><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> Map of Easter Island, or Rapa Nui / Te Pito Te Henua (Navel of the world) with the mentioned localities (after THOMSON 1891).</span><br /><br />This scenario is based primarily on the discovery during an archaeology expedition prior to 1961 of unknown palm-like pollen in sediments, on an island today lacking completely any native tree species. In subsequent years further cores were analysed for pollen, also root imprints in soil and subfossil nuts found in caves supported the claim that the island was covered by a forest in past times.<br /><br /><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifgLSPQWvwHwZk3QCrPRFCmA8pPRXRarlHt7S6QxP1B7k2s5FsuZ4C3jIEWAO9VncTt8De_wZEbZKHEEgJhte_C4-3z40C4n9fUijxJ3FIlj3z6hmwaKxaFs3moZFRvD7F_9KjQMmctBo/s1600/THOMSON_1891_Rongorong,.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 212px; height: 174px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifgLSPQWvwHwZk3QCrPRFCmA8pPRXRarlHt7S6QxP1B7k2s5FsuZ4C3jIEWAO9VncTt8De_wZEbZKHEEgJhte_C4-3z40C4n9fUijxJ3FIlj3z6hmwaKxaFs3moZFRvD7F_9KjQMmctBo/s320/THOMSON_1891_Rongorong,.jpg" alt="" id="BLOGGER_PHOTO_ID_5470088394203493442" border="0" /></a></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3. </span>Rongorongo, the unique "scripture" of Rapa Nui is still a mystery. The displayed symbol is interpreted to represent or be inspired by a palm tree (after THOMSON 1891).</span><br /><br />Today Rapa Nui is covered by meadows (90%), planted Eucalyptus trees (5%), shrublands (4%) dominated by invasive plant species and pioneer and urban vegetation (1%).</span> <span style="font-family:arial;"><br /><br />Until today the number of studied cores to reconstruct the paleoecology of the island is limited, and most were analyzed with a very coarse resolution and present mayor sedimentary gaps, so many doubts remain how fast and when Rapa Nui lost entirely it´s forests.<br /></span> <span style="font-family:arial;">According to recent palynological studies the island experienced a cold and dry climate until the end of the last glacial maximum ca. 12.000 years BP, then during the moister climate of the Holocene the forest expanded and persisted until the arrival of Humans AD 800 to 1200. Deforestation then presumably took place between these ages and the arrival of Europeans in 1800 AD.</span> <span style="font-family:arial;"><br /><br />There exist two major categories of hypothesis to explain the massive destruction of plant live and lose of species diversity on the island. Some <a href="http://www.youtube.com/watch?v=-hO-vCPuuQQ">hypothesis</a>, summarized in the book "Collapse", impute deforestation to direct and indirect human behaviour, clearing of the forest until the last tree and/or introducing invasive plant or animal species, that concurring with native species caused their extinction. Other hypothesis, more speculative, deal with a possible massive impact of past climate changes.<br /><br /></span><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzGpmsvKeM5C38K_GX8uMc57q1vRvu1oOUmtkYbaZcMMIpvzIkk7BPwaXvP9je3S0TyFFVigMzpzeT7Kz_4gI2svtRGv_QI-TwW3p9cUXe5_Ln9lIXl2iol1fcgU5gRDfmjus8CKLFMfw/s1600/RULLetal_2010_VolcanicCraters.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 359px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzGpmsvKeM5C38K_GX8uMc57q1vRvu1oOUmtkYbaZcMMIpvzIkk7BPwaXvP9je3S0TyFFVigMzpzeT7Kz_4gI2svtRGv_QI-TwW3p9cUXe5_Ln9lIXl2iol1fcgU5gRDfmjus8CKLFMfw/s400/RULLetal_2010_VolcanicCraters.jpg" alt="" id="BLOGGER_PHOTO_ID_5470088043572687186" border="0" /></a></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.4.</span> </span></span> <span style="font-family:arial;"><span style="font-size:85%;">Pictures of the three volcanic craters with continuous cores used for pollen analysis. A) Rano Aroi, B) Rano Kao and C) Rano Raraku (photos by V. Rull from RULL et al. 2010).</span><br /><br />Sediment records of the island past can be obtain from the swamps and lakes situated in the larger craters of the volcanic island, because larger sediment traps are more likely to hold thicker and undisturbed sediments. Rano Aroi crater holds a bog with an outflow and connections to the groundwater table. Rano Raraku and Rano Kao craters hold permanent lakes without outflows and are disconnected from the main groundwater bodies by impermeable lacustrine sediments. </span> <span style="font-family:arial;"><br /><br />The count of pollen grains in sediment recovered from a core of the lake Ranu Raraku shows a replacement of palm-dominated by grass-dominated pollen assemblages in the sedimentary record as of 1200 AD.<br /><br /></span><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOhiqwDR_Zd_oeFM3EUE9dEdW369zGncDmVd4Gn65FXul8ex8vP28bLJ5y2FanFctRdPfBsO8UAwNRpPXzSiM2ARQG4jYZCT67YtiwqXNt0GnjJ2y5hwOiok9ULb1V5F5-Mc0yHVbkuos/s1600/MANNetal_2008_PollenDiagram.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 218px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOhiqwDR_Zd_oeFM3EUE9dEdW369zGncDmVd4Gn65FXul8ex8vP28bLJ5y2FanFctRdPfBsO8UAwNRpPXzSiM2ARQG4jYZCT67YtiwqXNt0GnjJ2y5hwOiok9ULb1V5F5-Mc0yHVbkuos/s400/MANNetal_2008_PollenDiagram.jpg" alt="" id="BLOGGER_PHOTO_ID_5470087604099524738" border="0" /></a></span></span></span><span style="font-weight: bold;font-size:85%;" >Fig.5.</span></span><span style="font-size:85%;"> </span><span style="font-family:arial;"><span style="font-size:85%;">Percentage pollen diagram from Rano Raraku compared to charcoal concentration in the analyzed sediment. The calibrated C14 ages show a major gap in sedimentation between 800 and 4.000BP. The decline of palm pollen and increase in charcoal (a proxy for anthropogenic induced fires) happens shortly after this presumed gap (from MANN et al. 2008).</span><br /><br />Unfortunately interpretation of pollen diagrams can be very tricky.<br />Pollen sum curves do reflect a relative change in pollen production, which not necessarily reflect the absolute number of palm trees in the surrounding. Depending on the tree species, and if it is pollinated by animals or by wind, different species can produce very different quantities of pollen. To correct this error a calibration factor must be known.<br /><br /></span><span style="font-family:arial;">The tree species that produced the pollen on Rapa Nui is unknown. Pollen-morphological similarities exist to widespread species on pacific islands like <span style="font-style: italic;">Pritchardia</span>, <span style="font-style: italic;">Cocos </span>(coconut) and <a href="http://en.wikipedia.org/wiki/Jubaea_chilensis"><span style="font-style: italic;">Jubaea chilensis</span></a> (wine palm). But sparse macroremains, like the damaged nuts, seems to discard all mentioned species (assuming that all known remains like roots, pollen and nuts represent only one species), and are more similar to the nuts of <span style="font-style: italic;"><a href="http://en.wikipedia.org/wiki/Juania_australis">Juania australis</a>,</span> an endemic palm species on the Juan Fernández Islands.<br />Based on these remains finally the extinct species <span style="font-style: italic;">Paschalococos disperta</span>, with dubious systematic affinities to recent tree species, was established. So the pollen calibration factor for the extinct species can not more obtained.</span><br /><br /><span style="font-family:arial;">The pollen signal conserved in the bog also depends strongly from the location of trees in the catchment. Few trees very near the shore of a lake can give stronger signals that many trees located in great distance.<br /><br /></span><span style="font-family:arial;">On Easter Island the sedimentological records shows a prominent gap in the last centuries and millennia, maybe as result of a major drought and dry out of the studied lakes, unfortunately just in the time where the strongest human impact is postulated.</span><br /><span style="font-family:arial;">In the end pollen records can give only approximately ages of vegetation changes occurring between 1900 and 600 years BP, but not the extent and cause of such changes.</span> <span style="font-family:arial;"><br /><br />The number of former palm trees on the island was estimated by density of root imprints to 16 million, covering up to 70% of the surface. But these numbers are in contrast to the small amount of charcoal or wood fragments recovered until now on the island., It is however possible that the missing wood-debris and charcoal was eroded, transported and deposited in the surrounding ocean.<br /><br />Considering the mentioned problems arising from the reconstruction of the former vegetation by means of pollenanalysis, the observed pollen data can also be explained by the presence of sparse forest patches or small numbers of trees growing near the shores of the studied lakes or on steep slopes, until finally the arrival of Europeans and their cattle and goats finished off the last survivors.</span> <span style="font-family:arial;"><br /><br />The intriguing questions remains, did the former inhabitants lumber completely the island's dense subtropical forest to still their megalomaniac hunger for bigger and bigger moai, and finally caused their own demise, or was Rapa Nui since the beginning of human colonization a sensible and tree poor ecosystem, and climatic causes like a drought combined with human impact caused an inexorable collapse?<br />The available botanical data still don't allow an exclusion of one or the other scenario.<br /><br /><span style="font-size:85%;">References:<br /><br />THOMSON, W.J. (1891): <a href="http://www.archive.org/details/cu31924105726222">Te Pito Te Henua, or Easter Island. </a>Report of the National Museum 1888-89, Smithonian Institution. Washington<br />RULL, V.; CANELLAS-BOLTA, N.; SAEZ, A.; GIRALT, S.; PLA, S. & MARGALEF, O. (2010): <a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V62-4YCS045-1&_user=10&_coverDate=04%2F30%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1331574324&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6474c96809a059e956875f325bf91a6d">Paleoecology of Easter Island: Evidence and uncertainties.</a> Earth-Science Reviews 99:50-60 doi:10.1016/j.earscirev.2010.02.003<br />MANN, D.: EDWARDS, J.; CHASE, J.; BECK, W.; REANIER, R.; MASS, M.; FINNEY, B. & LORET, J. (2008): <a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WPN-4RH2SWR-1&_user=10&_coverDate=01%2F31%2F2008&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1331574539&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c28af1e2bf3165a430bbe449dcc96a07">Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island).</a> Quaternary Research 69:16-28 doi:10.1016/j.yqres.2007.10.009 <a href="http://www.bio-nica.info/biblioteca/Mann2008EasterIsland.pdf">Fulltext (pdf)</a><br /><br />Introductory Picture from <a href="http://en.wikipedia.org/wiki/Easter_Island">Wikipedia</a><br /></span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-72771644941580336612010-05-09T09:35:00.000-07:002010-05-09T11:10:45.050-07:00The first geological map depicting loess (1865)<div style="text-align: justify;"><span style="font-family:arial;">Loess is silt dominated sediment with minor amounts of sand and clay. This homogenous particle distribution is a result of the formation of the up to hundred of meters thick massive deposit; it's a terrestrial, windblown sediment, most time with homogenous bright, yellowish colour. Primary sedimentary structures in loess are subtle, so the true origin of this sediment was for a very long time unclear. Lyell in his first editions of Geology books interpreted loess as fluviatile loam.*<br /><br />Loess covers a significant amount of the Earth's land surface, perhaps as much as 10%. Because of its widespread distribution, texture and mineralogy, it forms some of the world's most important agricultural soils.</span><br /><span style="font-family:arial;">There exist two main models to explain the formation and distribution of loess. The classical hypothesis interpret it as primarily glacial eroded and reworked material, from where the finer fractions become subsequently selective transported and accumulated by wind. </span> <span style="font-family:arial;">The second model explain the main source of the windblown material to coming from deserts or arid areas, not necessarily related to glaciers, as a result of dry climate conditions during glacial periods.</span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br /></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXBRN8XtSgbk2PoeqB2RZt9Q_VI5ya9E4L8UO3G1XBtOLWzO80y-xHacO2ocL8_8OhXBn2kbrP4Rd96XUERwysSa3VFIHI8rnC4F3PfAWMHXdKkT4wBwyMm8xM9222RU55SVhvCHv5dRE/s1600/FRANZ_VON_HAUER.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 258px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXBRN8XtSgbk2PoeqB2RZt9Q_VI5ya9E4L8UO3G1XBtOLWzO80y-xHacO2ocL8_8OhXBn2kbrP4Rd96XUERwysSa3VFIHI8rnC4F3PfAWMHXdKkT4wBwyMm8xM9222RU55SVhvCHv5dRE/s400/FRANZ_VON_HAUER.jpg" alt="" id="BLOGGER_PHOTO_ID_5469311489536549250" border="0" /></a></span></span></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.1.</span> Carl Maria PAUL, Guido STACHE and in the middle Franz Ritter VON HAUER, the author of the first loess map of Central Europe.</span></span><br /><br /><span style="font-family:arial;">The geologist Franz Ritter von Hauer was the second Director of the Geological Survey in Vienna (1866-1885). One of his main contributions to Quaternary science was the geology textbook of the former Austro-Hungarian Monarchy, which provided a resource to access recent developments in geology and notably loess research to many scientists. In the middle of the 19th century he also coordinated the geological mapping of the monarchy, initiated mainly for economical reasons to record the mining activities and map future potential mineralogical resources.<br />Even if quaternary sediments were not the primary interest of the project, Hauer tried to establish a first approach to mapping and classification of these deposits.<br /><br /></span> </span><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtJjo1m-kDyDGk9KVuobv6I-NuzdPBJ4uVb7e9YhtTm7wG87goLpSUm-T1wA4vSTFl9l9wqtImj1I_hl__VxwYrcMFwUM8-f42bXOLgKFvtSUCG-uaVN80dUQvUsUJYGF5iotyE0mAqbw/s1600/Geo_Map_Austria_complete_1850.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 291px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtJjo1m-kDyDGk9KVuobv6I-NuzdPBJ4uVb7e9YhtTm7wG87goLpSUm-T1wA4vSTFl9l9wqtImj1I_hl__VxwYrcMFwUM8-f42bXOLgKFvtSUCG-uaVN80dUQvUsUJYGF5iotyE0mAqbw/s400/Geo_Map_Austria_complete_1850.jpg" alt="" id="BLOGGER_PHOTO_ID_5469311318016228594" border="0" /></a></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> The second edition of the General Geological General Map of the Austro-Hungarian</span></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"> Monarchy compiled by von Hauer (Archive of the Austrian Federal Geological Survey) compare to Fig.4. for the loess formation (mainly yellow and ligth green coloured area), from </span></span></span><span style=";font-family:arial;font-size:85%;" >GAUDENYI & JOVANOVIC 2010.</span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3atQDX_S2Vy2SrXGrYmnxDuPm98xeoYbPjm7KcAmPFNYT4vzTlcV-L7oiYe1O6gqOXalOQPPOqUAFV4IOOXQU_hezN8i4Xv0UbpY3XXLzYGq5pr3CtyOR2OGUWAFz92Gu-mbBhQRFPP4/s1600/Geo_Map_Austria_1850.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 330px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3atQDX_S2Vy2SrXGrYmnxDuPm98xeoYbPjm7KcAmPFNYT4vzTlcV-L7oiYe1O6gqOXalOQPPOqUAFV4IOOXQU_hezN8i4Xv0UbpY3XXLzYGq5pr3CtyOR2OGUWAFz92Gu-mbBhQRFPP4/s400/Geo_Map_Austria_1850.jpg" alt="" id="BLOGGER_PHOTO_ID_5469311140914078338" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span> Enlargement of the map in Fig.2.</span><br /><br />The General Geological Map of the Austro-Hungarian Monarchy presented in 1865, and produced between 1850 and 1856, was one of the most comprehensive and complete geological map of Central Europe during that period of time. </span> <span style="font-family:arial;"><br /><br />The Quaternary formations were subdivided in two groups: Pleistocene and Holocene formations. The Pleistocene formations identified as "Dilluvial" included predominantly fluvial gravels and sand, but also loess. </span> <span style="font-family:arial;">The Holocene formations were denominated "Alluvial" and included peat, lime tuff, quicksand and other formations summarized only as "Alluvial formations". </span> <span style="font-family:arial;"><br />Loess was mentioned exclusively as a Pleistocene ("Dilluvial") formation and the distribution clearly outlined, even if, for lack of detailed knowledge, the definition differs from the modern understanding of loess . In the Austrian geological map for example, the loess formation in some areas also included "loess-like" sediments, as for example colluvial deposits. </span> <span style="font-family:arial;"><br /><br />Nevertheless it was one of the first maps which documented the extent of loess deposits in Europe and West Asia.<br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6_3VKRw-q7ylurfhV6eaoI53sZo4b6Plo8Zd7_12iX3n6QnrQJTU2raAStOsFVgku3xVxk9vhyphenhyphenPc3t5eEJruCYP75knCglvYndDmJbIJGZJu3JfFJq_HSsXpoi4HGZsPwSuNTvQOOX8I/s1600/HAASEetal_2007_LoessMapEurope.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 282px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6_3VKRw-q7ylurfhV6eaoI53sZo4b6Plo8Zd7_12iX3n6QnrQJTU2raAStOsFVgku3xVxk9vhyphenhyphenPc3t5eEJruCYP75knCglvYndDmJbIJGZJu3JfFJq_HSsXpoi4HGZsPwSuNTvQOOX8I/s400/HAASEetal_2007_LoessMapEurope.jpg" alt="" id="BLOGGER_PHOTO_ID_5469310544549810034" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.4.</span> <a href="http://www.ufz.de/index.php?en=15536">Modern map of loess distribution, from HAASE et al. 2007.</a></span></span> <span style="font-family:arial;"><br /><br />*The Student's Elements of Geology (1870): <span style="font-style: italic;">"In some parts of the valley of the Rhine the accumulation of similar loam, called in Germany "loess," has taken place on an enormous scale [several hundred feet thick]. Its colour is yellowish-grey, and very homogeneous; and Professor Bischoff has ascertained, by analysis, that it agrees in composition with the mud of the Nile. Although for the most part unstratified, it betrays in some places marks of stratification, especially where it contains calcareous concretions, or in its lower part where it rests on subjacent gravel and sand which alternate with each other near the junction. Although this loam of the Rhine is unsolidified, it usually terminates where it has been undermined by running water in a vertical cliff, from the face of which shells of terrestrial, freshwater and amphibious mollusks project in relief. These shells do not imply the permanent sojourn of a body of freshwater on the spot, for the most aquatic of them, the Succinea, inhabits marshes and wet grassy meadows."</span></span> <span style="font-family:arial;"><br /><br /><span style="font-size:85%;">REFERENCES:<br /></span></span> <span style=";font-family:arial;font-size:85%;" ><br />GAUDENYI, T. & JOVANOVIC, M. (2010): <a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VGS-4YWYYVP-5&_user=10&_coverDate=04%2F21%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1328414477&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=138531eecb84c24cfb42ad49d0140f60">Franz Ritter von Hauer's work and one of the first loess map of Central Europe. </a>Quaternary International. 10.1016/j.quaint.2010.04.008</span> <span style=";font-family:arial;font-size:85%;" ><br />HAASE, D., FINK, J., HAASE, G., RUSKE, R., PECSI, M., RICHTER, H., ALTERMANN, M., JÄGER, K. D. (2007): <a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4NF2NN0-1&_user=10&_coverDate=05%2F31%2F2007&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1328412532&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=76a84fbe604a78d835d3a34b903f9170">Loess in Europe - its spatial distribution based on a European Loess Map, scale 1:2,500,000.</a> Quaternary Science Reviews 26 (9-10), 1301-1312</span> </span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com2tag:blogger.com,1999:blog-7510048715512322715.post-83759585128844857112010-05-07T13:02:00.000-07:002010-05-07T13:13:45.987-07:00Biggest Beaver Dam Ever<div style="text-align: justify;"><span style="font-family:arial;">The actual location of the world longest <a href="http://rockglacier.blogspot.com/2009/03/holocene-beaver-damming.html">beaver dam</a> (that is until someone find a longer one) is just south of Lake Claire, about 190 km to the NNE of Fort McMurray, inside Wood Buffalo National Park, Northern Alberta- Canada.<br />The dam has a length of about 850 meters and It has at least existed at this spot for over 15 years , aerial photo's show that this dam did not exist in 1975.</span><br /></div><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgd5rjMrBBTPJCiYn0p5muBIM4U-ofARBp-qGbi1gKSkCnIo-HLFIX8U-BHKZEqE9phGEUdHjah5wlonb6If0ZVhtf-nisBWDjK21uHFSXDO01cp7_BFpr7sGKDcGFU4iwMvUedzDk12-U/s1600/longest-dam-GE-li.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 333px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgd5rjMrBBTPJCiYn0p5muBIM4U-ofARBp-qGbi1gKSkCnIo-HLFIX8U-BHKZEqE9phGEUdHjah5wlonb6If0ZVhtf-nisBWDjK21uHFSXDO01cp7_BFpr7sGKDcGFU4iwMvUedzDk12-U/s400/longest-dam-GE-li.jpg" alt="" id="BLOGGER_PHOTO_ID_5468622409504539538" border="0" /></a><span style="font-size:85%;"><a href="http://www.geostrategis.com/p_beavers-longestdam.htm"><span style="font-family:arial;">Fig.1.</span></a><br /></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com1tag:blogger.com,1999:blog-7510048715512322715.post-2178168673237976992010-04-27T12:23:00.000-07:002010-04-27T12:35:51.974-07:00Arkology<div style="text-align: center;"><a href="http://news.yahoo.com/s/afp/20100426/lf_afp/hongkongturkeyreligionarchaeologynoahsark"><span style="font-family:arial;">Evangelists claim 'Noah's Ark' discovery on Turkish mountain.</span> </a><br /></div><div style="text-align: center;"><div style="text-align: center;"><br /><span style="font-size:100%;"><span style="font-family:arial;">So my theory that it was/is hidden in area 51 is not more supported ?<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtGBd-hn2RvuVby5XuWvT0-qe07NkYcfalE_LdxxnfHgo7Nk3b5LkqnMoBS9-1a5RtnbtLFdgMoFSVp1bthWhBRkLaWFtWuMyECoc2wsihn4A2kWO56tbYvtKKcWcMKSEE-6Qt4xY5Ijc/s1600/Raiders_Of_The_Lost_Ark_Warehouse.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 264px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtGBd-hn2RvuVby5XuWvT0-qe07NkYcfalE_LdxxnfHgo7Nk3b5LkqnMoBS9-1a5RtnbtLFdgMoFSVp1bthWhBRkLaWFtWuMyECoc2wsihn4A2kWO56tbYvtKKcWcMKSEE-6Qt4xY5Ijc/s400/Raiders_Of_The_Lost_Ark_Warehouse.jpg" alt="" id="BLOGGER_PHOTO_ID_5464901294694598130" border="0" /></a></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> With the wood of the ark you could make a lot of crates...</span><br /><br />To be continued...<br /></span></span></div></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-42485115970342201822010-04-22T12:40:00.000-07:002010-04-27T12:42:53.994-07:00Volcano god angry - lets sacrifice the geologist<span style="font-size:100%;"><span style="font-family:arial;">Natural events or presumed catastrophes will always lure from their hideouts religious fanatics and other self declared experts.</span></span><br /><br /><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">The ongoing eruption on Island for example was interpreted as a side effect of the HAARP-Project, related to sun activity and first signs of the end of the world (coming in 2012).<br />No wonder that even the official religon(s) now have to contribute their explanation - the Italian theologian Antonio Rungi (I presume he is catholic) sees it as divine act: "<span style="font-style: italic;">The volcanic cloud that blocked air transport in Europe is - if we interpret it in the light of the Gospel and the Apocalypse - certainly a proof of God. Just a volcanic eruption to undermine the whole system, this makes us realize how precarious we are".</span><br /><br /></span></span><div style="text-align: center;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtV_uUCmDGorUhRwU1ifRMBD2YrOrqcJdraANCBs_fALYRXguJaHSQCAiau_IJFaUywohCEwyUSHwZtSYLRYHjyOoj8BEuAYsqVbGHzRHiuhn49TNzRZAHAJaOXkcNpeLs27FjM_KEplc/s1600/PBF179-Special_Delivery.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 133px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtV_uUCmDGorUhRwU1ifRMBD2YrOrqcJdraANCBs_fALYRXguJaHSQCAiau_IJFaUywohCEwyUSHwZtSYLRYHjyOoj8BEuAYsqVbGHzRHiuhn49TNzRZAHAJaOXkcNpeLs27FjM_KEplc/s400/PBF179-Special_Delivery.jpg" alt="" id="BLOGGER_PHOTO_ID_5463050415913783746" border="0" /></a></span></span><span style="font-size:85%;"><span style="font-family:arial;">Fig.1. Cartoon from <a href="http://pbfcomics.com/?cid=PBF179-Special_Delivery.jpg"><span style="font-style: italic;">The Perry Bible Fellowship</span></a></span></span></span></span></div><span style="font-size:100%;"><span style="font-family:arial;"><br />But this is not even the dumbest opinion on the eruption:<br />The <a href="http://ahrcanum.wordpress.com/2010/04/15/911-false-flag-volcanic-ash-grounds-flights-military-drills-continue/">NATO was also portrayed as guilty</a>, because the military exercise "<a href="http://www.eucom.mil/english/FullStory.asp?article=Icelands-volcanic-ash-halts-Europe-flights-ARDENT">Brilliant Mariner </a>" should to be hold just during the ongoing eruption and consequent closure of commercial air routes, and naturally from these “facts” some connections to 9-11 are postulated.<br />Funnier is the alleged connection of the Icelandic volcano to a <a href="http://ahrcanum.wordpress.com/2010/04/16/volcano-ash-cloud-conspiracy-photos-reveals-alien-faces-ufos/">possible extraterrestrial invasion</a>, Agent Spooky-Mulder would be pleased.<br /><br />Meanwhile the German bio-physician Dieter Broers is cited in the G</span></span><span style="font-size:100%;"><span style="font-family:arial;">erman tabloid BILD: “<span style="font-style: italic;">NASA images show just one day before the eruption the <a href="http://starobserver.org/ap100418.html">largest solar flare</a> in 15 years. - He is certain: The earth is heading to a doomsday triggered by the Sun in 2012.”<br /><br /></span><span>The tabloid, notorious known for its approach to science, continues with a list of other “incredible“explanations:</span><span style="font-style: italic;"><span style="font-style: italic;"><br /><br /></span></span><span>The German author Hartwig Hausdorf, dedicated “mystery researcher”, postulates a connection between the American <a href="http://www.haarp.alaska.edu/">HAARP-project</a> and the volcano, a other author, Walter-Jörg Langbein clearly sees a ethical motivation behind the behavior of the volcano – our civilization, like the Maya, is to arrogant and must be punished.<br /><br />Hydrobiologist and journalist Edgar L. Gärtner got the simplest of all explanations <span style="font-style: italic;">“There is no ash-cloud”.</span> The entire story is only a conspiracy and a deflection strategy to prepare a terror attack of incredible proportions.<br />What else? Maybe that the ash is a strategy of the living planet, named after the Lovelock hypothesis Gaia – to reduce the of CO2 influx by airplanes? Or got the old Vikings it right, and is Eyjafjallajökull only the beginning of Ragnarök, and will be Iceland the battle ground of Thor and the Midgard serpent ?<br /><br /></span></span></span><div style="text-align: center;"><span style="font-size:100%;"><span style="font-family:arial;"><span><span style="font-size:100%;"><span style="font-family:arial;"><span><span style="font-size:100%;"><span style="font-family:arial;"><span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-style: italic;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUEjEmLP9Zfmfs4CZVWD3jQXFASwWZWLKuaGjDUjmQLALKFp1zWQANRPvAQzXOwdUNTCNGwDbcgsCTBKaKSPcQVA6rob0zmoaqef-f3yh1YwX13SaHp_7kaCSsQLrQgkLGP3NeLFN9eXQ/s1600/Johann_Heinrich_Fuessli.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 284px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUEjEmLP9Zfmfs4CZVWD3jQXFASwWZWLKuaGjDUjmQLALKFp1zWQANRPvAQzXOwdUNTCNGwDbcgsCTBKaKSPcQVA6rob0zmoaqef-f3yh1YwX13SaHp_7kaCSsQLrQgkLGP3NeLFN9eXQ/s400/Johann_Heinrich_Fuessli.jpg" alt="" id="BLOGGER_PHOTO_ID_5464903956998888786" border="0" /></a></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> <a href="http://en.wikipedia.org/wiki/J%C3%B6rmungandr">Thor battles the terrible Jörmungandr</a> ( Heinrich Füssli 1788).</span></span></span></span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><span><br /></span></span></span><span style="font-size:100%;"><span style="font-family:arial;">Don´t even bother to ask a geologist... </span></span><span style="font-size:100%;"><span style="font-family:arial;"><span>It’s seems that a geological explanation like Iceland is sitting on top of a magmatic hot spot is too unrealistic. Let’s remind of the good times, and the religeous mumbo-jumbo when volcanoes where simply calmed by a human sacrifice - so let’s use some geologist, it’s seems that anyway nobody is listening to them.</span><span style="font-style: italic;"><br /></span></span></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com2tag:blogger.com,1999:blog-7510048715512322715.post-25317747333499888952010-04-20T12:52:00.000-07:002010-04-23T13:32:44.091-07:00Accretionary Wedge 24: Heroes VS Cartoons<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh81UzVjxhJVmKJcKH0vLQMI3inPS-uRn716ok8jsEVIxILuOFUWi3keVec3kvvb15BziLvx9dXahTCij4i-vfxMLck1_tdbgpRQkNTLvNEHoHTwnwnTa5GDjlcA0wXse87jwqMG2rqt1g/s1600/PUNCH_1885_Trilobite.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 147px; height: 200px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh81UzVjxhJVmKJcKH0vLQMI3inPS-uRn716ok8jsEVIxILuOFUWi3keVec3kvvb15BziLvx9dXahTCij4i-vfxMLck1_tdbgpRQkNTLvNEHoHTwnwnTa5GDjlcA0wXse87jwqMG2rqt1g/s200/PUNCH_1885_Trilobite.jpg" alt="" id="BLOGGER_PHOTO_ID_5462311640665906546" border="0" /></a><span style="font-size:100%;"><span style="font-family:arial;">Callan Bentley at <a href="http://mountainbeltway.wordpress.com/">Mountain Beltway</a> will be hosting the next edition of <span style="font-style: italic;">The Accretionary Wedge</span> and he is searching heroic earth scientists.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">I was influenced by many people in my approach to geology, contemporary parents, friends and teachers, but also by historic personalities in form of their biographies and achievements in science.<br />Nevertheless I wouldn't speak about them only as heroes - they were after all men, and displaying them as infallible scientist seems somehow to put them on an unattainable podium.<br />Let's also remember the words of the theoretical physicist Philippe Blanchard</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br /><span style="font-style: italic;">"The scientist should take the science seriously, but they should not take themselves to seriously."</span><br /><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">People that propose revolutionary ideas, ahead of their time, often get misunderstand, even attacked verbally and ridiculed. <a href="http://rockglacier.blogspot.com/2008/10/wiliam-smith.html">William Smith</a> for example, considered a pioneer of stratigraphy, was nicknamed "Strata-Smith" after his proposal that the earth is organized in defined layers. And the caricatures of <a href="http://darwin-online.org.uk/life25d.html">Charles Darwin</a> and Thomas Henry Huxley are today part of history.</span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br />On the other hand, some personalities gather such a reputation, that no critic is allowed or tolerated. Criticism can only be addressed in a indirect way, for examples by caricatures or satiric drawings.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">Even if it's exactly not the gentlemen's way (or perhaps it is - the best known examples are made by Victorian gentlemen in the golden age of geology in the years between 1780 and 1900) satirical drawings, in a certain manner, are a funny way to criticise - both in a fair or unfair manner.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">A caricature can refer to a portrait or a behaviour that is exaggerated or distorted, the sense of a satirical drawing is to capture the essence of a person or thing to create an easily identifiable visual likeness - the drawing should be simple, but unmistakable for someone that has some background information (for example knows the depicted person or the context) and transport as much meaning as possible. Although this kind of satire is usually meant to be funny, its deeper purpose is often an attack on something strongly disapproved by the satirist, using the weapon of wit.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">But these prerequisites make the drawings also a source of information's to explore the history of earth sciences, the caricatures carry a lot of information, not only about the depicted person or geological model, but also how new theories are accepted or refused by society, and as last but not least, the personal opinion of the caricaturist on the matter. </span></span><br /></div><div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;"><br />The first geologists had to face many prejudices and hostilities, like <a href="http://geotripper.blogspot.com/2009/09/how-come-only-presidents-get-carved-on.html">James Hutton </a>(1726-1797), facing the many critics of his ideas on deep time and rock formations.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">One of the most famous caricatures, depicted many times in books dealing with geology and palaeontology, was produced by the English geologist Henry De la Beche (1796-1855) to lampoon the theories of Charles Lyell.<br /><br /></span></span><div style="text-align: center;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfrHvH1EOxfypfipKvKFU7IqnobPc6zYgTWkG3G4BDJ_ksJKND_hUjy8rreKD4vFaJS-SdpJA5TrC-Yj6o4z6JVcLRZhUs2dmuuF1MDtZ-8gV8QTDPSNbQCLU-ho7IRa5F1x84kEDSBds/s1600/BECHE_1830_ProfIchthyosaurus.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 355px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfrHvH1EOxfypfipKvKFU7IqnobPc6zYgTWkG3G4BDJ_ksJKND_hUjy8rreKD4vFaJS-SdpJA5TrC-Yj6o4z6JVcLRZhUs2dmuuF1MDtZ-8gV8QTDPSNbQCLU-ho7IRa5F1x84kEDSBds/s400/BECHE_1830_ProfIchthyosaurus.jpg" alt="" id="BLOGGER_PHOTO_ID_5462311081583605986" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> "Awful Changes.", see also the <span style="font-style: italic;">Ichthyosaurus</span> installment at<a href="http://blogevolved.blogspot.com/2010/04/ichthyosaurs-in-art.html"> ART evolved</a>.</span></span></span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">The prominent "Professor <span style="font-style: italic;">Ichthyosaurus</span>" was considered first to represent William Buckland (1784-1856), but the geologist and dedicated earth-science historian Martin J.S. Rudwick realized the connection of this scene with some drawings produced in 1831 by De la Beche in his diary, where he ridiculed the uniformity-principle of Lyell.<br />Lyell proposed that even if earth is much older then previously thought, and the forces that sculpt the planet are inexorably but slow, these forces follow a eternal circle of climate and fauna - so in a distant future, after our recent ice age, it is may possible that after mammals again reptiles live in a greenhouse (note the palms in the background), following as highest "social class" the human race.<br /><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">In the <a href="http://www.strangescience.net/delabeche.htm">other drawings</a> of De la Beche diary a lawyer (the reference to Lyell seems obvious) is carrying a bag with "his" theory around the world, or he is shown wearing particular glasses to see the world in a personal view, and offering this "theoretical approach" to a geologist carrying a hammer, a reference to the applied working researcher. It's obvious that De la Beche could not overcome his prejudice against Lyell as a lawyer, that he considered much more a theory foreigner then a real researcher (considering how much Lyell travelled and how much geological phenomena he visited this is a very unfair insinuation).</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">In a second cartoon (brought to light by Haile 1997) De la Beche is mocking on the effects of present causes, operating at the same slow magnitude and rate throughout geologic history. We see a vast U-shaped valley, and in the foreground a nurse with a child.<br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2lmR-PSyEXnRYdt4ow999IekbvYPynNFgqJbBPeHOAS_PCdDzSCYVc9fJKvCd29YyMNWkDvIoV_iWiU2CTZ2CrpMLWHlThQnPe2U45IGdJiA3ksrUeO5-u3CWUnrzBMuiekl8JzQYOOE/s1600/BECHE_1830_LyellCaricature.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 209px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2lmR-PSyEXnRYdt4ow999IekbvYPynNFgqJbBPeHOAS_PCdDzSCYVc9fJKvCd29YyMNWkDvIoV_iWiU2CTZ2CrpMLWHlThQnPe2U45IGdJiA3ksrUeO5-u3CWUnrzBMuiekl8JzQYOOE/s400/BECHE_1830_LyellCaricature.jpg" alt="" id="BLOGGER_PHOTO_ID_5462310717514919698" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span> De la Beche´s cartoon of 1830-1833 mocking the effects of present causes. The cartoon is entitled "<span style="font-style: italic;">Cause and Effect".</span></span><br /><br />The child is peeing into the huge valley and a caption has his nurse exclaiming, '<span style="font-style: italic;">Bless the baby! What a valley he have made.!!!'</span></span></span> <span style="font-size:100%;"><span style="font-family:arial;"><br /><br />On the 24 July of 1837 the Swiss geologist <a href="http://gmcgeology.blogspot.com/2010/04/lous-agassiz-tracy-strauss-irrefutable.html">Agassiz</a> was to be thought to hold a lecture about his studies on fossil fishes - instead the members of the venerable Swiss Society of Natural Sciences heard from their young president a theory, emerged some years before, to explain the origin of erratic blocks and scratches on rocks in the Alps. <span style="font-style: italic;">"O Sancte de Saussure, ora pro nobis!"</span> - O holy de <a href="http://rockglacier.blogspot.com/2008/09/erratic-boulders.html">Saussure</a>, pray for us, was the only comment of the German geologists Leopold von Buch (1774-1853) as he left the room. Another proposed great idea caused disbelief in the public and gave cartoonist much to work on. Agassiz showed in his study "Études sur les glaciers" (1840) that glaciers were the explanations of erratic blocks and scratches on rocks in the Alps, the idea of a large ice cap covering the Alps, and the Ice Age was ready to meet the broader public.<br /><br />Agassiz introduced with his former mentor Buckland in the autumn of 1840 the glacial theory to the British Isles.<br /><a href="http://fossilsandotherlivingthings.blogspot.com/2010/04/not-my-geological-hero-better-than-that.html">Professor Buckland</a>, was a highly respected scientist, but also eccentric and very perky, and in a first moment struggled with the idea of his friend Agassiz, but became convinced after he saw the spurs of glaciers and moraine deposits in the Alps and Scotland.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">Maybe the public was anyway chuckling over the debate about the importance that highly respected men gave to this apparently tiny marks on rocks, in every case the well-known mining engineer Thomas Sopwith (1803-1879) thankfully poked fun on his fellow countryman and on the subject of the dispute.</span></span><br /><br /><div style="text-align: center;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt0cj0ZnOrutUyfnn1ncc_jW0xMsKySbIeE3CpL1JLHz8rIpEOLP8_0DigEKDZ4mMS-pqdiyf06AcKjfnphXHmjZHYCVNGEUJaf2upExOXGDLbPgjgKw6wOLVjOThfkDkOMDxOl_c4P4U/s1600/SOPWITH_CostumeGlaciers.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 259px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt0cj0ZnOrutUyfnn1ncc_jW0xMsKySbIeE3CpL1JLHz8rIpEOLP8_0DigEKDZ4mMS-pqdiyf06AcKjfnphXHmjZHYCVNGEUJaf2upExOXGDLbPgjgKw6wOLVjOThfkDkOMDxOl_c4P4U/s400/SOPWITH_CostumeGlaciers.jpg" alt="" id="BLOGGER_PHOTO_ID_5462310377047534066" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;font-family:arial;" >Fig.4. </span> </span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;">Costumes of the Glacier.</span></span></span><br /></div><span style="font-size:100%;"><span style="font-family:arial;"><br />The cartoon sketch that he scratched/draw of the Professor, titled <span style="font-style: italic;">"Costumes of the Glaciers"</span>, shows Buckland dressed for fieldwork. The numerous captions are difficult to read, but the lines at Buckland's feet are noted to be <span style="font-style: italic;">"Prodigious Glacial Scratches"</span> produced by "<span style="font-style: italic;">the motions of an IMMENSE BODY, not allow to change its course upon Slight Resistance"</span> (we ignore if this is referred to the glacier or the appearance of Buckland). Buckland holds - like all true geologist do - a geological map under his arm, a <span style="font-style: italic;">"Map of Ancient Glaciers"</span>.</span></span> <span style="font-size:100%;"><span style="font-family:arial;">On the erratic stones scattered around his feet's captions tell, that this stone was scratched 33.333 years ago, but on a other rock this prodigious age is relativated, claiming that a similar looking stone was just scratched by the wheel of a passing cart, just the day before yesterday, and in the background it's seems that some new scratches are just in the making by a passing carriage.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">Caricatures and cartoons can bring science and scientific discussion to the attention of a broader public, but to appreciate them, they have to be understood.<br />What I choose, are only two examples and theories, and many others were <a href="http://rockglacier.blogspot.com/2009/11/geo-art-inconvenient-truth-about.html">worth to be told</a>, but they show us how certain geologists and their support of new ideas have influenced society, and how they were seen by their contemporaries, and how society understand (sometimes wrongly) the work of the researchers.</span></span><span style="font-size:100%;"><span style="font-family:arial;"><br /><br />We are only humans - and maybe that’ s the most important teaching that cartoons can give to us.<br /><br /><span style="font-size:85%;">BIBLIOGRAPHY:</span></span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />BROWNE, J. (2001): <a href="http://www.blogger.com/www.amphilsoc.org/sites/default/files/410.pdf">Darwin in Caricature: A Study in the Popularisation and Dissemination of Evolution. </a>Proceedings of the American Philosophical Society 145(4): 496-509<br />CLARY, M.R. & WANDERSEE, J.H. (2010): <a href="http://www.springerlink.com/content/tu2hr74734776514/">Scientific Caricatures in the Earth Science Classroom: An Alternative Assessment for Meaningful Science Learning.</a> Sci & Educ 19:21-37<br /></span></span><span style="font-size:85%;"><span style="font-family:arial;">GORDON, E.O. (1894): <a href="http://www.archive.org/details/lifecorresponden00gordrich">The Life and Correspondence of William Buckland.</a> John Murray, London</span><br /></span><span style="font-size:85%;"><span style="font-family:arial;">LEEDER, M.R: (1998): <a href="http://sp.lyellcollection.org/cgi/reprint/143/1/95.pdf">Lyell's Principles of Geology: foundations of sedimentology. </a>Geological Society, London, Special Publications 143: 95-110</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />MACDOUGALL, D. (2004): <a href="http://books.google.at/books?id=ySR-YMZsPl8C&pg=PA57&lpg=PA57&dq=Costume+of+the+Glaciers+buckland&source=bl&ots=zwJm_YdVGe&sig=9ORIsK-KBprcRFLWZKGOEdm2GPI&hl=de&ei=j5UaS7fsAqaInAOMyOzYAw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBYQ6AEwAw#v=onepage&q=Costume%20of%20the%20Glaciers%20buckland&f=false">Frozen Earth - The once and future story of Ice Ages. </a>University of California Press, Berkely-Los Angels.</span></span> <span style="font-size:85%;"><span style="font-family:arial;"><br />RUDWlCK, M. S. (1975): <a href="http://www.jstor.org/pss/228926">Caricature as Source for the History of Science: DE LA BECHE'S Anti-Lyellian Sketches of 1831.</a> Isis, Vol. 66 (234): 534--560<br />RUDWICK, M.J.S. (2005): <a href="http://books.google.it/books?id=6gRv7Zx6wHQC&printsec=frontcover&dq=The+Reconstruction+of+Geohistory+in+the+Age+of+Revolution&source=bl&ots=bACWRj1XWs&sig=1UwNr9avH2Lmuc-kr3VeUFbac6M&hl=it&ei=y8DNS5XdPOGHOISRyf4P&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAYQ6AEwAA#v=onepage&q&f=false">Bursting the Limits of Time. The Reconstruction of Geohistory in the Age of Revolution. </a>The University of Chicago Press.<br /><br />Introduction Image: <span style="font-style: italic;">The Trilobite</span>, cartoon from T<span style="font-style: italic;">he Punch</span> 1885<br /></span></span> </div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com2tag:blogger.com,1999:blog-7510048715512322715.post-62306396130615018262010-04-16T11:02:00.000-07:002010-04-24T06:55:48.610-07:00Tephrostratigraphy<div style="text-align: justify;"><span style="font-family:arial;">The ongoing eruption of the Icelandic volcano Eyjafjallajokull caused much interest in the geoblogosphere (<a href="http://aldopiombino.blogspot.com/2010/04/gli-imprevedibili-svluppi-delleruzione.html">Italy</a>, <a href="http://geopedrados.blogspot.com/2010/04/aviacao-e-vulcanismo-no-publico.html">Portugal</a>, <a href="http://throughthesandglass.typepad.com/through_the_sandglass/2010/04/eyjafjallajokulled-stranded-in-the-usa.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ThroughTheSandglass+%28Through+The+Sandglass%29">U.S.A</a> and <a href="http://outsidetheinterzone.blogspot.com/2010/04/boh-dee-oh-dee-oh-foom.html">Outside,</a> <a href="http://geology.about.com/b/2010/04/16/volcanic-havoc-in-the-air.htm">geologists</a> - but also <a href="http://dinosauriart.blogspot.com/2010/04/so-yesterday-i-started-blogging-about.html">paleontologists</a> get interested, and of course <a href="http://magmacumlaude.blogspot.com/2010/04/volcano-vocab-3-tephra.html">magmaliceous</a> volcanologists <a href="http://scienceblogs.com/eruptions/2010/04/eyjafjallajokull_eruption_cont.php">here</a> and <a href="http://volcanism.wordpress.com/2010/04/16/some-eyjafjallajokull-links/">here</a>) mainly because of the spectacular pictures available, but it's a reminder also for an interesting phenomenon, related with Quaternary geology. (so we got also Quaternologists).<br /><br />Large volcanic eruptions throw huge amounts of ash and aerosols in the upper parts of the atmosphere, here atmospheric currents take the particles and distribute them widely, in some cases even around the planet. Sometimes this ash, or better it's effect, is seen in the sky, the dust particles and sulfur droplets deflect the sunlight during sun rising and setting, and turn the sky in vivid red colours. </span><span style="font-family:arial;"> The fine particles will float in the atmosphere for months or even years, and finally sink to the bottom of the air ocean and deposit on the landscape.</span><br /><br /></div><div style="text-align: justify;"><span style="font-size:100%;"> <span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiC8xkqbiK8GELPiP8E9QI1THmXr1np6gbixzG-ckRRC2OJUU3VWeDKW8uR8lhN2gSkcYytsAC9p8umb8Z5JTmpvIYv2L-mVkjQn4-Qf89ua85C8FCMcXPd2Hfj3VKV_awa1MQPrSaGcYw/s1600/19052006_LacLautreyDryas4.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiC8xkqbiK8GELPiP8E9QI1THmXr1np6gbixzG-ckRRC2OJUU3VWeDKW8uR8lhN2gSkcYytsAC9p8umb8Z5JTmpvIYv2L-mVkjQn4-Qf89ua85C8FCMcXPd2Hfj3VKV_awa1MQPrSaGcYw/s400/19052006_LacLautreyDryas4.jpg" alt="" id="BLOGGER_PHOTO_ID_5460803226738584610" border="0" /></a></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1. </span>Tephra layer of the Laacher See volcanic eruption dated to 12.900+-560yr BP (with dendrological cross-references 12.916yr BP) in the limnic marls of the French lake Lautrey.</span><br /><br />So ash deposits, or <a href="http://magmacumlaude.blogspot.com/2010/04/volcano-vocab-3-tephra.html">Tephra</a>, have very special features:<br /><br /></span> <span style="font-family:arial;">-they are erupted over very short time periods, geologically speaking, usually a matter of only hours or days to perhaps weeks or months</span><br /><br /><span style="font-family:arial;">-they can be spread widely over land and sea to form a thin blanket that (unless reworked) has the same age wherever it occurs. </span> <span style="font-family:arial;"><br /><br />- The volcanic minerals can be dated by radiometric methods (Argon40-Argon39 for example)</span><br /><br /><span style="font-family:arial;">- For some events we possess written reports, so if the layer is attributed to a determinate eruption, we can very precisely date the sediment. Historical accounts have provided accurate eruption years for many eruptions in countries where volcanic activity is common, in particular during the last 200-300 yr. In Europe historic events are recorded for 1783, when the ashes originated from the Icelandic Laki volcano reached the continent, Tambora in 1815 (recognized as volcanic event in Europe only with ongoing scientific research in 1855), Krakatau in 1883</span>.<br /><br /><span style="font-family:arial;">Therefore, once it is identified by its mineralogical and geochemical properties, a tephra layer provides a time-parallel marker bed or isochron for an 'instant' in time, and with this marker horizons a Tephrochronology of sediments can be established. Tephrostratigraphy' is another term that is commonly used and refers to the study of sequences of tephra layers and related deposits and their relative ages. Sigurdur Thorarinsson, an Icelandic volcanologist (who else?) is widely regarded as the modern 'father of this discipline, he realized in the twenties of the past century that the numerous Icelandic tephra layers offered great possibilities for correlation and dating.<br />After the first pioneering work, studies of tephra layers spread in the 1920s and 1930s in New Zealand, Japan, Iceland, South America and USA.</span><br /><br /><span style="font-family:arial;">In Europe important sources for quaternary volcanic ashes are the larger volcanic districts, like Iceland, the Italian volcanoes (comprising active volcanoes as the Pleistocene volcanoes of Monticchio), the Auvergne in France, the Eifel in Germany with the important marker horizon of the <a href="http://www.tephrabase.org/cgi_bin/tbase_lst1.pl?country=x">Laacher See Tephra</a>, the (ex-)Thera volcano in the Mediterranean Sea.<br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO3u_O5GIMddzEXzYRm8mzGmUiIV3z5wjz-9tOiETkLhE6njfEkL3uf4HZVy5CRpLN6apK89gYlh2QR86K-tszoDPfQOTU2exolHfudqy3DImib9XcSyE2ESZ9kjA6J-zBdAitKFa9d00/s1600/ALLOWAYetal_2007_Tephra_Europe.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 299px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO3u_O5GIMddzEXzYRm8mzGmUiIV3z5wjz-9tOiETkLhE6njfEkL3uf4HZVy5CRpLN6apK89gYlh2QR86K-tszoDPfQOTU2exolHfudqy3DImib9XcSyE2ESZ9kjA6J-zBdAitKFa9d00/s400/ALLOWAYetal_2007_Tephra_Europe.jpg" alt="" id="BLOGGER_PHOTO_ID_5460802866326041122" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2.</span> Known distribution of major tephra localities and related volcanic districts. Iceland - Vedde Ash (VA), Germany - Laacher See (LST), and Italy - Neopolitan Yellow Tuff (NYT). The locations of the principal volcanic centers that were active during the period ca. 18.5 to 8 14C kyr BP are also identified (from ALLOWAY et al. 2007). It´s interesting to note that the fossil Vedde Ash distribution is similar to the<a href="http://www.spiegel.de/fotostrecke/fotostrecke-53906-3.html"> recent ash-plumes over Europe</a> (and <a href="http://rapidfire.sci.gsfc.nasa.gov/gallery/?2010105-0415/NorthAtlantic.A2010105.1135.2km.jpg">here</a>).</span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEFfkLO39BqGiKm0jULFdfnEidh7f_JNGwrrDNz82xCXWCBmlgrhrmu5UZ1zxSNzYCK29DKBqLBiA4MKSUk16vNa_wu31g465vRUbQ6iJPDvyR0mkQsGXVvYgM1L-GH989JYuiHIpopE4/s1600/SCHMINCKEetal_1999_LST.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 263px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEFfkLO39BqGiKm0jULFdfnEidh7f_JNGwrrDNz82xCXWCBmlgrhrmu5UZ1zxSNzYCK29DKBqLBiA4MKSUk16vNa_wu31g465vRUbQ6iJPDvyR0mkQsGXVvYgM1L-GH989JYuiHIpopE4/s400/SCHMINCKEetal_1999_LST.jpg" alt="" id="BLOGGER_PHOTO_ID_5460802545187521586" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span></span><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">Fig.2.</span> (a) Areal distribution and (b) isopach map of major Laacher See Tephra fans in Central Europe. Dashed line: outer detection limits of distal tephra layers. The signatures refer to different ash-units with different composition and deposition characteristics; LLST= Lower Laacher See Tephra, MLST= Mid Laacher See Tephra, ULST= Upper Laacher See Tephra (from SCHMINCKE et al. 1999).</span><br /><br /><span style=";font-family:arial;font-size:85%;" >REFERNCES:</span> <span style="font-size:85%;"><br /></span><span style=";font-family:arial;font-size:85%;" >ALLOWAY, B.V. et al. (2007): Tephrochronology. In (ed): ELIAS, S.A. (2006): Encyclopedia of quaternary science. Elsevier</span> <span style=";font-family:arial;font-size:85%;" ><br />SCHMINCKE, H.S.; PARK, C. & HARMS E., 1999: Evolution and environmental impacts of the eruption of Laacher See Volcano (Germany) 12,900 a BP; Quaternary International 61, 61-72</span> </span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com1tag:blogger.com,1999:blog-7510048715512322715.post-5396781927460788472010-04-15T12:00:00.001-07:002010-04-15T13:01:39.905-07:00Taphonomy of hominid sites, or what geology can tell us about our origins<div style="text-align: justify;"><span style="font-family:arial;">Since a French geology student visited the remote region nearly 50 years ago, and brought back tales of fossil rich sediments, the area around the river Awash is considered a "must seen" for paleoanthropologists and geologist interested in the natural history of Africa.</span><br /><br /></div> <span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhstPTijpuEvmLVdWNznhSVo2HaO7KRzhmzPUwCzaqI3GEgkefX7yg2gzlvz2o7r6N0rl4mLgfExt5QK67qzeAcTjiKHmqzxNdrZLsQDC_zUiZr5GHP4nRCWoYl8N8yiLLhEBRH3_hykK8/s1600/GIS_Africa_Hominid_Sites.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 283px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhstPTijpuEvmLVdWNznhSVo2HaO7KRzhmzPUwCzaqI3GEgkefX7yg2gzlvz2o7r6N0rl4mLgfExt5QK67qzeAcTjiKHmqzxNdrZLsQDC_zUiZr5GHP4nRCWoYl8N8yiLLhEBRH3_hykK8/s400/GIS_Africa_Hominid_Sites.jpg" alt="" id="BLOGGER_PHOTO_ID_5460442719374077458" border="0" /></a><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> Mentioned hominid bearing sites, Aramis near the river Awash in Ethiopia and Malapa in South Africa.</span><br /><br /></span><div style="text-align: justify;"><span style="font-family:arial;">The presentation to the public of <span style="font-style: italic;">Ardipithecus ramidus</span>, found at the site of Aramis in the catchment area of the river Awash, in October 2009 was a media event comparable to the presentation last week of <span style="font-style: italic;">Australopithecus sediba</span> from South Africa.<br />But both described species are only a part of the recuperated evidence (in case of A. ramidus nearly 150.000 bone fragments), behind <span style="font-style: italic;">A. ramidus</span> there lie 15 years of research, behind <span style="font-style: italic;">A. sediba </span>2 years - the paleontological and geological results of both sites shamefully received little attention in the mass media.</span> <span style="font-family:arial;"><br />But the careful collection and examination of animal and plant fragments, and the geological framework, was rarely well documented as by these two discoveries.</span> <span style="font-family:arial;"><br /><br />The proposal of Darwin that Africa is the cradle of humankind led to the idea that the last common ancestor, which we share with the great apes, lived like the recent chimpanzees or gorillas in a forest habitat.</span> <span style="font-family:arial;">Then, in 1925, the discovery of the first <span style="font-style: italic;">Australopithecus</span> species, considered a early hominid, by Raymond Dart seemed to give further clues of human evolution.<br />The associated faunal remains showed that <span style="font-style: italic;">Australopithecus </span>lived in a grassland environment, it was therefore speculated that the open grasslands of Africa - developing in the Pliocene ice ages - were exploited by early hominids and were therefore somehow integrally involved with the origins of upright walking, a possible key factor of our further evolution.</span> <span style="font-family:arial;"><br /><br />But the sediments and the paleontological content of the Lower Aramis Member (Sagantole Formation) at Aramis provided evidence that <span style="font-style: italic;">Ar. ramidus </span>lived in a predominantly woodland setting - upright walking of early hominids was therefore primarily not an adaption to overlook or to colonize a grassy savanna. </span> <span style="font-family:arial;"><br /><br />Taphonomic assemblages often represent a collection of a variety of animals of different geographically locations and time periods. Carcasses of animals from different environments can be washed together, or natural traps, like caves, act as sample bag for many centuries, providing a false species assemblage. Accurate interpretation of fossil assemblages can be challenging.</span> <span style="font-family:arial;">In the case of Aramis however, the sampled stratigraphic unit is sandwiched between two volcanic horizons, which yielded approximately the same age (4.4Ma), supporting the idea that the fossils represent a short time intervall.</span><br /><span style="font-family:arial;">The fossils of Aramis comprise a large variety of plants and animals, including insects, molluscs and bones of owls, parrots, porcupine, hyenas, bears, elephants, ancient horses, giraffes, antelopes and rhino.</span> <span style="font-family:arial;"><br />The recovered bones of birds and mammals came from species living in, or associated with, closed forest or shrublands.</span> <span style="font-family:arial;">One of the common larger mammals found associated with Ardipithecus is the spiral-horned antelope, or kudu (<span style="font-style: italic;">Tragelaphus</span>).</span><br /></div><span style="font-family:arial;"><br /></span><div style="text-align: justify;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEPKPB1PR2gBLCnS_kvqX2r5x46uVUZZE5ozI4TDxxC2CkEdBdjyS7x0J-behL0T3BMkGVgBu4r3yFE6_80Ksc4a3X0_5dUS0k7rhajo-6WGsv88aJL8bnvqPE8kOKgPiY0HeIzz0_AUE/s1600/BRESSAN_2006_07_16.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEPKPB1PR2gBLCnS_kvqX2r5x46uVUZZE5ozI4TDxxC2CkEdBdjyS7x0J-behL0T3BMkGVgBu4r3yFE6_80Ksc4a3X0_5dUS0k7rhajo-6WGsv88aJL8bnvqPE8kOKgPiY0HeIzz0_AUE/s400/BRESSAN_2006_07_16.jpg" alt="" id="BLOGGER_PHOTO_ID_5460442389345329106" border="0" /></a></span></span></span></span><span style="font-weight: bold;font-family:arial;font-size:85%;" >Fig.</span></span><span style=";font-family:arial;font-size:85%;" ><span style="font-weight: bold;">2.</span> A not so scientific reconstruction of a possible hominid habitat.</span><br /><br /><span style="font-family:arial;">Today, these antelopes are browsers eating mostly Leaves, and they prefer bushy to wooded habitats. In contrast, remains of grazing antelopes are rare in the Aramis assemblage.</span> <span style="font-family:arial;"><br />The environment of these animals can also be reconstructed by analyzing their teeth's. Carbon isotopes from tooth enamel yield dietary information because different isotope signatures reflect different photosynthetic pathways of plants consumed during enamel development. Therefore, animals that feed on tropical open-environment grasses (or on grass-eating animals) have different isotopic compositions from those feeding on browse, seeds, or fruit from shrubs or trees. The isotopic pattern of <span style="font-style: italic;">Ardipithecus </span>is also similar to that of <span style="font-style: italic;">Tragelaphus</span>, indicating little dietary intake of grass, and supporting the reconstruction that the animal lived predominately in the forest.<br /><br /></span><span style="font-family:arial;">Additionally, oxygen isotopes, found also in the molecular structure of the enamel, can be used to reconstruct the relative humidity and evaporation (temperature) in the environment where the animal, and with it the teeth grow.</span><br /></div><span style="font-family:arial;"><br /><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHxgQ5wnZ3F9z8VGv6Bf364Lbljy6Ag1OTqqy6isWmzQSlA2I30WGjUFmJGR7T2MGpgkyIyJN469Z51QeUaug9Nh5lmXm80Rg9N0tCn8ivx0jQIe_DE1TJKaK8FanVuGEs8OpULbfxFCk/s1600/WHITEetal_2009_Isotopes.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 262px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHxgQ5wnZ3F9z8VGv6Bf364Lbljy6Ag1OTqqy6isWmzQSlA2I30WGjUFmJGR7T2MGpgkyIyJN469Z51QeUaug9Nh5lmXm80Rg9N0tCn8ivx0jQIe_DE1TJKaK8FanVuGEs8OpULbfxFCk/s400/WHITEetal_2009_Isotopes.jpg" alt="" id="BLOGGER_PHOTO_ID_5460441653918103410" border="0" /></a></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span> after WHITE et al.2009. Isotopic signature of fossil enamel from the Aramis Member.</span><br /><br /></span><div style="text-align: justify;"><span style="font-family:arial;">The death of an animal is the last act in life, and the first step to go lost forever, or in rare cases become buried deep within earth, get fossilized and in even more rare cases being excavated by naked monkeys. But how to reconstruct these events, where no living eyewitnesses are allowed?<br /><br />Let's see what the rocks can tell us.</span> <span style="font-family:arial;">The two skeletons of <span style="font-style: italic;">Australopithecus sediba </span>were discovered in <a href="http://rockglacier.blogspot.com/2009/08/fissures-holes-and-caves.html">cave infillings of the karst landscape</a> of South Africa, in a massive, up to 1.5-m-thick stratigraphic unit containing abundant, well-preserved macro- and micromammal fossils, including articulated remains of <span style="font-style: italic;">Equus sp</span>.</span> <span style="font-family:arial;"><br />The poorly sorted, coarse-grained and cemented sandstone consists of grains with diameters ranging from 0.5 to 2.5 mm of quartz, chert, dolomite, peloids and, less commonly, iron oxide-coated grains, ooids, shale, and feldspar.</span> <span style="font-family:arial;">Angular limestone blocks (smaller than 50 cm) and flowstone fragments (smaller than5 cm) occur throughout this facies. The heterogenic lithological composition tells us that the sediment - or parts of it- is allochtonous, the material of this facies was transported, maybe from outside, and deposited in the cave.</span><span style="font-family:arial;"><br /></span></div><span style="font-family:arial;"><br /><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbV-EI4GDdgbfuELv681fUt2kly1ZRbaVh014fanCvEo96131DhnXNRBqc47OuJSmv06VhXRtYNXHtVyh6Jo-a_c3FEeXPvgwnUSiyy5qdevJtjY4QeOHTZ3Kxb-VIiXjj705TRhVpBA4/s1600/DIRKetal_2010_Geology.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 248px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbV-EI4GDdgbfuELv681fUt2kly1ZRbaVh014fanCvEo96131DhnXNRBqc47OuJSmv06VhXRtYNXHtVyh6Jo-a_c3FEeXPvgwnUSiyy5qdevJtjY4QeOHTZ3Kxb-VIiXjj705TRhVpBA4/s400/DIRKetal_2010_Geology.jpg" alt="" id="BLOGGER_PHOTO_ID_5460441286365579314" border="0" /></a></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.4.</span> Geological map of the Malapa site, after DIRKS et al. 2010.</span></span> <span style="font-size:85%;"><span style="font-family:arial;">The fossils of hominids where interbedded in facies D. The underlying flowstone was also <a href="http://rockglacier.blogspot.com/2009/08/dating-cave-sediments.html">dated</a> by U-Pb on an age of ca. 2 Ma.</span></span><br /><br /><div style="text-align: justify;"><span style="font-family:arial;">The heterogeny in the grains, ranging from sand to pebbles to larger boulders and fossils, and lacking sedimentary structures (like stratification) suggest the deposition of the unit as a single event, like a debris flow, maybe caused by a flood or a storm. The superb preservation and state of articulation of fossil material also indicate rapid deposition, limited transport distance, and laminar flow conditions consistent with debris flows. </span> <span style="font-family:arial;"><br /><br />These new data and the combination of different scientific approaches questions old certainties. The case of <span style="font-style: italic;">Ardipithecus</span> suggests that the anatomy and behaviour of early hominids did not evolve in response to open savanna or mosaic settings.</span> <span style="font-family:arial;"><br />In the case of<span style="font-style: italic;"> A. sediba</span> the geology tell us how hominids become fossilised and where we must search for them. The fossils found with <span style="font-style: italic;">A. sediba </span>helped also to date the new species, and confirmed the radiometric ages, a faunal analysis is still missing, but who knows if further investigations will not force us again to change our understanding how we evolved.</span> <span style="font-family:arial;"><br /><br /><span style="font-size:85%;">REFERENCES:</span></span><span style=";font-family:arial;font-size:85%;" ><br />BERGER et al. (2010): <a href="http://www.sciencemag.org/extra/sediba/">Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa.</a> Science, 328: 195-204</span> <span style=";font-family:arial;font-size:85%;" ><br />DIRKS et al. (2010): <a href="http://www.sciencemag.org/extra/sediba/">Geological Setting and Age of Australopithecus sediba from Southern Africa.</a> Science, 328: 205-208</span> <span style=";font-family:arial;font-size:85%;" ><br />LOUCHART et al. (2009): Taphonomic, Avian, and Small-Vertebrate Indicators of Ardipithecus ramidus Habitat. Science 326: 66-66e4: DOI 10.1126/science.1175823</span> <span style=";font-family:arial;font-size:85%;" ><br />WHITE et al. (2009): Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus. Science 326: 67-93; DOI 10.1126/science.1175822</span> <span style=";font-family:arial;font-size:85%;" ><br />WOLDEGABRIEL et al. (2009): The Geological, Isotopic, Botanical, Invertebrate, and Lower Vertebrate Surroundings of Ardipithecus ramidus. Science 326: 65-65e5; DOI 10.1126/science.1175817</span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-298864826563580562010-04-13T12:56:00.000-07:002010-04-13T12:58:50.125-07:00Peru glacier breaks up, causes tsunami<div style="text-align: justify;"><span style="font-family: arial;">A part of a glacier broke off and plunged into a lake in Peru, causing a 23m tsunami wave that swept away at least three people and destroyed a water processing plant serving 60,000 local residents, government officials said Monday. From <a href="http://www.msnbc.msn.com/id/36445899/ns/world_news-americas/">msnbc</a><br /><br /></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-39081408169748568962010-04-12T08:42:00.001-07:002010-04-13T07:08:37.359-07:00Landslide in South Tyrol causes train derailment<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">Bozen, 12 April 2010: 9 confirmed victims, 23 people injured, these are the latest sad information’s about a rail crash between the towns of Latsch and Kastelbell in the South Tyrolean “Etschtal”, occurred at 9.00 p.m. this morning. The railway between the two localities follows the orographic right bank of the main river of the valley “Etsch/Adige” in a gorge eroded by the river in Holocene sediments (manly a large alluvial fan coming from south with unconsolidated debris-flow deposits).</span><br /><br /></span></div><div style="text-align: justify;font-family:arial;"><span style="font-size:100%;">A landslide of 400 cubic meters - with a width of 10 to 15 meters, and a thickness of 2m - bursted off 50m above the railway line and hit the first wagon of the train, that was just passing by in direction of Kastelbell, causing the train derailment.<br /><br />To clarify possible causes of the landslide, geological investigations are underway. Eye witnesses reported large quantities of water running down the slope after the accident. A site investigation by the authorities preliminary concluded, that it’s possible that the rupture of an irrigation system above the location of the accident (the area is used for agriculture and farming) saturated the soil and underlying sediments with water, causing a mudslide just in the moment the train passed the point. The irrigation system, after the winter, was used since the last week, it’ s seems that at least in the last days to hours water infiltrated in the underlying slope. It’s also possible that the vibrations of the approaching train triggered finally the slide.<br /><br /><span style="font-size:100%;"><span style="font-size:100%;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTmJzpr5Ap5tVpC1xBLPMivFGTyd9FhVW0qle5-K0-4Midy8Nu80LUlDu2trLPSW741uDhWHjqHU3fh0iyy4pBz6lMJgslpIhVDCc3O0BGTXjZKJwzujEwUdaRgXLL7eUB899wkMFPVU4/s1600/Latsch_Kastelbell_Landslide.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 233px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTmJzpr5Ap5tVpC1xBLPMivFGTyd9FhVW0qle5-K0-4Midy8Nu80LUlDu2trLPSW741uDhWHjqHU3fh0iyy4pBz6lMJgslpIhVDCc3O0BGTXjZKJwzujEwUdaRgXLL7eUB899wkMFPVU4/s400/Latsch_Kastelbell_Landslide.jpg" alt="" id="BLOGGER_PHOTO_ID_5459621930224671650" border="0" /></a></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.1.</span> Location of the mudslide between the towns of Latsch and Kastelbell, ca. 1,4km after Latsch, from where the train was started some minutes before the accident (yellow circle) - the railway line follows the escarpment of the river “Etsch/Adige” between the two towns. The landslide happened on the orographic right bank of the river, in soil and sediments of a large alluvial fan. Coordinates of image centre: 46°37`43´´N and 10°52´54´´E (<a href="http://www.provinz.bz.it/informatik/themen/maps-webgis.asp">Product of the Autonomous Province of Bozen/Bolzano - South Tyrol</a>)</span><br /><br /><span style="font-size:130%;">I wish to express my condolence to the families of the victims, and thank the emergency services for their rapid intervention - only minutes after the accident they arrived on the place, and worked until now (11 hours) to rescue injured peoples.</span><br /></span></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-11978500113251335232010-04-04T04:05:00.000-07:002010-04-04T04:21:35.985-07:00MAMOHTEHKA MAMA<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPNOGthbOK3e6BJK4TKpwD7R3yoAhj8ZUrEO5zo9rEak2dyyVkoQKiqwyl4vU_oD2DYTM1y1pAEmCYhEIvJ7oOh-vXSg84UwzWfFMDX_ca6spRK1A9I0-sGFF98UNaff4o1Xq1aViwQkM/s1600/Dima_Societ_Cartoon.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 151px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPNOGthbOK3e6BJK4TKpwD7R3yoAhj8ZUrEO5zo9rEak2dyyVkoQKiqwyl4vU_oD2DYTM1y1pAEmCYhEIvJ7oOh-vXSg84UwzWfFMDX_ca6spRK1A9I0-sGFF98UNaff4o1Xq1aViwQkM/s200/Dima_Societ_Cartoon.jpg" alt="" id="BLOGGER_PHOTO_ID_5456237254252649650" border="0" /></a><span style="font-size:100%;"><span style="font-family:arial;">"Mom for baby-mammoth" is an old soviet cartoon inspired by the discovery of baby "Dima" in 1977. This little masterpiece tells the story about baby mammoth that miraculously avoided</span></span><span style="font-size:100%;"><span style="font-family:arial;"> extinction and started the quest for his mom search (found on <a href="http://siberianmammoth.com/">Siberian Mammoth</a>).</span></span><br /></div><br /><object height="385" width="640"><param name="movie" value="http://www.youtube.com/v/t-xbAYgvjCg&color1=0xb1b1b1&color2=0xcfcfcf&hl=en_US&feature=player_embedded&fs=1"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/t-xbAYgvjCg&color1=0xb1b1b1&color2=0xcfcfcf&hl=en_US&feature=player_embedded&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" height="325" width="410"></embed></object>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-1063198960483723012010-03-27T06:59:00.000-07:002010-03-27T07:59:51.941-07:00Accretionary Wedge #23: That is not dead which can eternal lie<div style="text-align: justify;"><span style="font-size:100%;"><span style="font-family:arial;">The March 2010 Accretionary Wedge is being hosted by <a href="http://geologyhappens.blogspot.com/2010/03/new-accretionary-wedge.html">Ed at Geology Happens</a>, and here's the proposed theme:</span></span><br /></div><div style="text-align: justify;"><br /><span style="font-style: italic;font-size:100%;" ><span style="font-family:arial;">"This AW is to share your latest discovery with all of us. Please let us in on your thoughts about your current work. What you are finding, what you are looking for. Any problems? Anything working out well?</span></span><span style="font-style: italic;">"</span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">Well, considering even only the Holocene of the Alps there is a major hiatus of knowledge, and I can provide only a humble, but maybe interesting piece of considerations on the problem:</span></span><br /><br /><span style="font-style: italic;font-size:100%;" ><span style="font-family:arial;">"That is not dead which can eternal lie,</span></span><br /><span style="font-style: italic;font-size:100%;" ><span style="font-family:arial;">And with strange aeons, even death may die"<br /></span></span><span style="font-size:100%;"><span style="font-family:arial;">H.P. Lovecraft (1890-1937)</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">A major unknown factor in rock glacier research is the formation age of these features. But for the understanding of climatic significance, and possible reaction of permafrost in a warmer climate, these information's are very important. Rock glacier develop mostly well about the tree-line, and in areas with strong debris accumulation, a difficult habitat for plants to growth. So in the rubble of rock glaciers organic matter, which would allow a 14C dating, is mostly missing.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">Exceptions are known from the Swiss Alps, in the rock glacier "Murtèl" HAEBERLI et al. (1999) were able to date moss remains, and in an actual paper BOMMER et al. (2010) describe the discovery of wood fragments of larch in the front of an (in)active rock glacier.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">Sometimes active rock glaciers override peat deposits, that can be dated, (EVIN & BEAULIEU 1985). Exposure age determinations of boulders on the surface, for example by cosmic rays or OSL are problematic because of the unstable surface that reworks constantly the material.</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">Evidence for a relative age can be supplied by the weathering of rocks, and lichen vegetation on blocks, but also here the moving surface cause troubles, the conditions of lichen growth and surface alteration change with time, so that the final date will be a mixture of different ages or at beast only an extreme value.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">All these methods may provide only a maximum or minimum age, and are connected with a number of methodological problems; also an important question is what reflects these dates? The original rock wall exposure to erosion, the formation and deposition of the rock fragments in the talus, the mobilization of the talus by permafrost creep? And what if rock glaciers experience phases of inactive and active periods?<br /><br />So it's no wonder that estimated ages of rock glaciers range from recent times, or formation during the last glacier high stands in the 16. and 19. century to interpretations of late glacial relics with ice 1.000 of years old (PALACIOS & VAZQUEZSELEM 1996; HUMLUM 1996; KÄÄB et al. 1997).</span></span><span style="font-size:100%;"><span style="font-family:arial;"><br /><br />The rock glacier that I studied in the last years reaches with his front the Lazaun pasture (Ötztaler Alpen) and it is a possible good candidate for an extensive research on internal structure and dynamics of permafrost in the Alps. </span></span><br /><br /><span style="font-size:100%;"><a style="font-family: arial;" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwCFfKTL7dJByrBddtmwf8J-8zBdO3N-xDDIV7Qf7vg63SirTRxGGtxwudSZNB-mlVkbb5t9a7Gdq9R5Uwh_ubhDwDPOeo3oLQMwHch0OzhxvWENQVAvs_bu72IGMWhqpiP0-bqHSByWs/s1600/BRESSAN_Lazaun.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 142px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwCFfKTL7dJByrBddtmwf8J-8zBdO3N-xDDIV7Qf7vg63SirTRxGGtxwudSZNB-mlVkbb5t9a7Gdq9R5Uwh_ubhDwDPOeo3oLQMwHch0OzhxvWENQVAvs_bu72IGMWhqpiP0-bqHSByWs/s400/BRESSAN_Lazaun.jpg" alt="" id="BLOGGER_PHOTO_ID_5453313620252754578" border="0" /></a></span><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-weight: bold;">Fig.1.</span> The Lazaun pasture with the bog and in te background the active rock glacier. From the front of the rock glacier a glacial river flow from the left to the right, exposing a sequence of peat deposits and sand/pebble layers.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">An extensive survey was carried out, geomorphological mapping, GeoRADAR, GPS and hydrological measurements. Also I tried to get some information's about the age of, so local legends tell, this petrified dragon.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">A connection of the rock glacier with the glacier high stand of the alpine Little Ice Age is supported in part by <a href="http://rockglacier.blogspot.com/2008/10/lichenometry.html">lichenometry </a>and moraine stratigraphy, which suggests an age of several hundred years. If, however, the measured GPS velocities are used to derive an age estimation (considering the length and the velocities of creep) the age ranges from 2.200 to 1.300 years. These observations relative the published ages of rock glaciers inferred simply by creep velocities (HAEBERLI et al. 1997), rock glaciers don't creep always at the same rate; reacting to climate change they display a complex behaviour.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">A tentative approach to determinate the long term behaviour of the rock glacier is the interpretation of a stratigraphical column in peat deposits in front of the rock glaciers. The outcrops created by a glacial river expose a peat-sediment sequence in an alpine fen.<br /><br /><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvH_9uRDrZEaHw3RivGAlnQ2fv2rV_bm-IQZw0kcSRJ1PYpwANMtc5eYASWqd58ecDma8MCl2FpRlnhIZP_x0AW_qEChrPBpszAuOJ7J-mN9PeHowQ_XJTJSBLDCUdqvuN5fl7qEzpLmo/s1600/BRESSAN_Lazaun_Outcrop.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 318px; height: 238px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvH_9uRDrZEaHw3RivGAlnQ2fv2rV_bm-IQZw0kcSRJ1PYpwANMtc5eYASWqd58ecDma8MCl2FpRlnhIZP_x0AW_qEChrPBpszAuOJ7J-mN9PeHowQ_XJTJSBLDCUdqvuN5fl7qEzpLmo/s400/BRESSAN_Lazaun_Outcrop.jpg" alt="" id="BLOGGER_PHOTO_ID_5453315023592404386" border="0" /></a></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.2</span>. Outcrop, GeoRADAR measurements and soundings showed that the peat is pretty deep, up to 3m.<br /><br /></span>There were several peat layers (at least four) alternating with clastic sediments (sand and pebbles), also, as a small sensation, wood fragments where found and recovered (the actual tree line is lowered by climatic and anthropogenic influence by some hundred meters).</span></span><br /><span style="font-size:100%;"><span style="font-family:arial;">Similar sequences are known in the Austrian part of the Ötztaler Alpen, where they were interpreted as a glacier advance - glacier retread cycle. (BORTENSCHLAGER 1984). I myself observed similar sediments in the <a href="http://www.rieserferner.de/">Rieserferner mountain group</a>, so such records are not rare, and have much potential for future research on the Holocene history of the Southeast-Alps.</span></span><br /><br /><span style="font-size:100%;"><span style="font-family:arial;">The sediments so maybe represents the varying climatic conditions in front of the rock glacier, during climatic favourable conditions moss and peat plants flourished and build up the peat layer, during cold periods the glacier and rock glacier advanced, providing more erosion and a source of clastic sediments that form the sand and pebble layers.<br /><br />And because finally the wintertime is over, I hopefully soon will go back to the rock glacier and dare to interfere in his sleep...<br /><br /></span></span><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:85%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><span style="font-size:100%;"><span style="font-family:arial;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlDNPxvaE2zJSV4gjnHIp0KtuM1AcX1IKSQFs3oVv6Htgdw5BOa-SspDChCBaor3553eBcQm73Ck9x4dOlChRWfFxFsOrhRZuW0XiLuIlSKrlp97D4jM6rXkgvf7y9V2M2OyIRtDyHC_E/s1600/BRESSAN_Lazaun_Stratigraphy_Foto.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlDNPxvaE2zJSV4gjnHIp0KtuM1AcX1IKSQFs3oVv6Htgdw5BOa-SspDChCBaor3553eBcQm73Ck9x4dOlChRWfFxFsOrhRZuW0XiLuIlSKrlp97D4jM6rXkgvf7y9V2M2OyIRtDyHC_E/s400/BRESSAN_Lazaun_Stratigraphy_Foto.jpg" alt="" id="BLOGGER_PHOTO_ID_5453315670894861154" border="0" /></a></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><span style="font-size:85%;"><span style="font-weight: bold;">Fig.3.</span> Peat layers in transition to grey mud and pebbles.</span><br /><br /><span style="font-size:85%;"><span style="font-family:arial;">REFERENCES:</span><br /></span><span style="font-size:85%;"><span style="font-family:arial;">BORTENSCHLAGER, S. (1984): Beiträge zur Vegetationsgeschichte Tirols I. Inneres Ötztal und unteres Inntal. Berichte des Naturwissenschaftlich-Medizinischen Vereins in Innsbruck. 71, 19 - 56.</span></span><br /><div style="text-align: justify;"><span style="font-size:85%;"><span style="font-family:arial;">EVIN, M. & BEAULIEU, J.L. (1985): Nouvelles données sur l´age de la mise en place et les phases d´activite du glacier rocheux de Marinet 1 (Haute-Ubaye, Alpes de sud francaises). Mediteranee. 4: 21-30</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">HAEBERLI, W.; KÄÄB, A.; WAGNER, S.; VONDERMÜHLL, D.; GEISSLER, P.; HAAS, J.N.; GLATZELT-MATTHEIER, H. & WAGENBACH, D. (1999): Pollen analysis and 14C-age of moss remains recovered from a permafrost core of the active rock glacier Murtèl/Corvatsch (Swiss Alps). Journal of Glaciology 45: 1-8</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">HUMLUM, O. (1996): Origin of Rock Glaciers: Observations from Mellemfjord, Disko Island, Central West Greenland. Permafrost and Periglacial Processes 7: 361-380</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">KÄÄB, A.; HAEBERLI, W. & GUDMUNDSSON, G.H. (1997): Analysing the Creep of Mountain Permafrost using High Precision Aerial Photogrammetry: 25 Years of Monitoring Gruben Rock Glacier, Swiss Alps. Permafrost and Periglacial Processes 8(4): 409-426</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">PALACIOS, D. & VAZQUEZSELEM, L. (1996): Geomorphic effects of the retreat of Jamapa glacier, Pico de Orizaba volcano (Mexico). Geografiska Annaler 78A(1): 19-34</span></span><br /><span style="font-size:85%;"><span style="font-family:arial;">SCAPOZZA, C.; LAMBIEL, C.; REYNARD, E.; FALLOT, J.-M.; ANTOGNINI, M. & SCHOENEICH, P. (2010): Radiocarbon Dating of Fossil Wood Remains Buried by the Piancabella Rock</span></span><span style="font-size:85%;"><span style="font-family:arial;"> Glacier, Blenio Valley (Ticino, Southern Swiss Alps): Implications for Rock Glacier, Treeline and Climate History. Permafrost and Periglac. Process. 21: 90-96</span></span><br /></div></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0tag:blogger.com,1999:blog-7510048715512322715.post-13322041946564293312010-03-25T14:30:00.000-07:002010-03-25T14:38:12.290-07:00Understanding Climate’s Influence on Human Evolution<div style="text-align: center;"><a href="http://notes.nap.edu/2010/03/05/new-books-this-week-climates-influence-on-human-evolution-and-more/"><span style="font-size:100%;"><span style="font-family:arial;">Free e-book</span></span></a></div>David Bressanhttp://www.blogger.com/profile/17650115671464472095noreply@blogger.com0