cryology and co.

The discovery of the periglacial realm

2011-07-07T08:12:00.001-07:00

The term periglacial was introduced by the Polish geologist Walery von Lozinsk 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 American Scientific Blog.

Climate research in the geologic past

2011-02-18T09:09:00.000-08:00

Fig.1. Global map as published by Lyell in his "Principles of Geology" (8th edition 1850) to illustrate the past climatic changes.

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.
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.

Read on how Lyell explained climate change by shifting "pseudo"-continents over the globe in the post at the American Scientific Guest Blog.

Glacier outburst floods threat

2011-01-11T11:03:00.000-08:00

Glaciers can influence societies in their catchment area in different ways, they act as a water storage for dry summers, but glaciers can also trigger geological catastrophes and endanger people.

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 occur in summertime when during melt-season large quantities of water can accumulate inside the glacier or as ice-dammed lake.

In the Andes and the Himalaya also a second type of floods is common, outbursts from moraine-dammed lakes, referred as glacial lake outburst flood (GLOF).
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. 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.

Fig.1. Laguna Paron (4.140m a.s.l. Cordillera Blanca - Peru, foto from Wikipedia) in 2009, a lake dammed by the debris-mantled glacier Hatunraju with a capacity of 75 million cubic metres before the lake level was lowered by 20 meters artificially by tunnelling through bedrock on the left of the moraine dam. The lake is surrounded by moraines 250m high. 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.
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.

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.
One of the best-documented outburst floods in Nepal took place on 4. August 1985 when the terminus of the Langmoche Glacier in the Khumbu Himal collapsed into Dig Tsho glacial lake (Video), creating a displacement wave hat overtopped the moraine dam and triggered its collapse. Estimated 10 million cubic metres of water were released - the wave destroyed a power plant and five people were killed and eroded and destabilized the valley floor for 90 kilometres downstream.

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 Tsho Rolpa (4.450m a.s.l.), fed by the Trakarding Glacier. By 2002 the lake 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.
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.
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.

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 continuing glacier retreat expected in the next decades the increase of problematic lakes (both in number and volume) will by of major concern in the future.

Fig.2. 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.
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 lake Luggye Tsho. A breach of the dam in 1994 led to severe flooding and loss of life up to 200 kilometres downstream. (ASTER-image by NASA, 08 June 2006).

Bibliography:

HAMBREY, M. & ALEAN, J.(2004): Glaciers. 2nd ed. Cambridge University Press: 377
HORSTMANN, B. (2004): Glacial Lake Outburst Floods in Nepal and Switzerland. New Threats Due to Climatic Change. Germanwatch - Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung.
KALTENBORN, B. P., NELLEMANN, C., VISTNESS, I. I. (Eds) (2010): High mountain glaciers and climate change - Challenges to human livelihoods and adaptation. United Nations Environment Programme, GRID-Arendal.

Modeling Glacier Change 2000-2100

2011-01-10T09:41:00.000-08:00

According to a simulation by researchers of the University of Alaska (RADIC, V. & HOCK, R.) 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 the actual ice volume.

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 balance of the glaciers.
The projections show in the 19 chosen glacierized regions different glacier retreat values, depending from factors like elevation, surface properties and effective temperature rise in the region.
According to the proposed 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 Caucasus.
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%.

I discussed a previous research dealing with possible effects of such glacier retreat on human society in this post.

Fig.1. 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 RADIC & HOCK 2011.

Fig.2. Example of glacier retreat in the Alps in the past 100 years: The Waxegg-glacier in the Zillertaler Alps at the border between Austria and Italy ca. 1900-1903 and 2006. Historic image from ROTHPLETZ, A. & PLATZ, E. (1903): Alpine Majestäten und ihre Gefolge - Die Gebirgswelt der Erde in Bildern, 268 Ansichten aus der Gebirgswelt.
For the history of glacier monitor projects see this post.

Bibliography:

RADIC, V. & HOCK, R. (2011): Regionally differentiated contribution of mountain glaciers and ice caps to future sea-level rise. Nature Geoscience doi:10.1038/ngeo1052

Cool Science at Scientific American

2011-01-03T11:31:00.001-08:00

Since antiquity snow-covered peaks have been ignored, avoided or even feared by men - up here apparently there was nothing to be gained.
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.

Thanks to Bora Zivkovic and the editors of Scientific American I was allowed to present A Short History of Glacier Science at the journal´s Guest Blog.

Fig.1. 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).

Bibliography:

BAILEY, R.H. (1983): Glacier. Time-Life Books, Amsterdam: 176

The discovery of the ruins of ice

2010-12-21T09:08:00.001-08:00

"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, 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 hardly need an inducement to enter into some inquiry respecting their nature and origin."

James, D. Forbes (1900): "Travels Trough the Alps." [page 17]

Fig.1. C. Wolf and M. Descourtis "La Grosse Pierre Sur Le Glacier de Vorderaar Canton de Berne Province d'Oberhasli", Amsterdam 1785.

Today worldwide glaciers were studied and monitored as climate proxies, 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 and monitor climate is an intriguing one, with many triumphs, setbacks and changes of mind.

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. 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 prison of damned souls (the Italian poet Dante Alighieri 1265-1321 imagined the centre of hell as a frozen wasteland) and the playground of demons, who from time to time send avalanches and debris flows into the valley.
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

"…there is no protection against the large quantities of 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...[]."

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, he studied anatomy, biology and geology, however regarding the glaciers of the Alps his ideas were somehow confused, 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 travelling scholars.

Between 1538 and 1548 glaciers were labelled (even if not depicted) with the term "Gletscher" on topographic maps of Switzerland. In his account on the Swiss land the Theologian Josias Simler in 1574 describes the Rhone-glacier.
The first historic depiction of a glacier is considered the watercolour-paint of 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.
In 1642 the Swiss editor Matthaeus Merian the Older in his "Topographie Helvetiae, Rhaetiae et Valesiae" published various copper engravings of glaciers, and in 1706 Johann Heinrich Hottinger is interested to explain the motion of "the mountains of ice" in his "Descriptio Montium Glacialium Helveticorum."
Johann Jakob Scheuchzer, visiting in the year 1705 the Rhône Glacier, published his observations of the "true nature of the springs of the river Rhône" in the opus "Itinera per Helvetiae alpinas regiones facta annis 1702-1711", and confirms the idea that glaciers are formed by the accumulation of snow and they move and flow.

Fig.2. The description of the Rhone glacier according to Scheuchzer´s "Itinera per Helvetiae alpinas regiones facta annis 1702-1711", the engraving shows the "false springs at the mountain Furca" (M, N, O - left and right of the picture) and the "true springs" (J, K, L) coming from the snout of the "great glacier" (A-F), surrounded by the "small glacier" (G, H).

The increasing interest to study glaciers in the Alps is also encouraged by enthusiastic travel reports; in his "Voyage pittoresque aux glaciers" the A.C. Bordier of 1773 describes the Bosson glacier as a "huge marble ruins of a devastated city".
The naturalist Horace Benedict de Saussure (1740-1799) is fascinated by the mountains of his homeland, he climbed mountains around Geneva since 1758, and after 1760 he travelled more than 14 times trough the Alps (considering the possibilities in this time an extraordinary achievement). Between 1767 to 1779 the first volume of his "Voyages dans les Alpes" 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, where the same lithology where found in the crystalline continental basement, like Precambrian metamorphic rocks and paleozoic sediments. The theory worked lesser to explain the foreland Alpine rocks - to transport boulders from the Alps the flood at least had to reach 1000 of meters.
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.
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.
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.

"Could it be proven to ourselves on the available documentation that both by the progress of our ice mountains as by our misbehaviour once for pasture most suitable land is currently covered by ice…[]"

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 "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.") discussed glacial theories during their lectures. And even Buckland, who still in 1831 argued "northern region of the earth seems to have undergone successive changes from heat to cold", in 1837 was converted to Lyell's uniformatism and considered that sudden changes, like an ice age and glacier expansion, simply don't happen in geology.

In 1815 Jean Pierre Perraudin, a chamois hunter in the Val de Bagnes, told to the engineer Ignatz Venetz 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.
He begun a detailed mapping project, and in 1834 Charpentier presented 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 student of Charpentier, named Jean Louis Rodolphe Agassiz, respected palaeontologist by the establishment. Charpentier invited Agassiz to visit the city of Bex and surrounding mountains, and to observe glaciers.
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 "Etudes sur les glaciers."
Agassiz experienced the same scepticism as many other ice-age proponents before.

"I think that you should concentrate your moral and also your pecuniary strength upon this beautiful work on fossil fishes .... In accepting considerable sums 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..."
Alexander von Humboldt in a letter to Agassiz on 2. December 1837

However Agassiz had good connections to the most important geologist of his time. Soon he could persuade William Buckland and later Charles Lyell. After that the most respected geologist gets convinced, the rest, as always, is history:

"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"
Edward Jackson, about an advice given by his professor Buckland in 1832

Fig.3. 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): "Preuves de l´existence d´anciens glaciers dans les vallées des Vosges."

Agassiz research on the Unteraar-glacier established the foundations of glaciology; he recorded the dimension of the glacier, his velocity and even ventured inside the glacier by passing trough a glacial mill. Soon after 1850 the measurements methods introduced by Agassiz were carried out on various glaciers of the Alps and repeated nearly every year.

Fig.4. 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.
"Aus den tiroler Alpen: Der Abschluß des Oetzthales mit dem Hochjochgletscher (links), dem Hintereisferner (in der Mitte) und dem Kesselwandferner (rechts oben). Nach der Natur gezeichnet von K. Schmetzer (1891)."

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.

Fig.5. 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.

Geology and Cyclicity: Milankovitch´s idea

2010-06-26T10:17:00.000-07:00

"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."

Milutin Milankovitch in 1950

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.
Five years later he returned to Belgrad where he found employment as professor for mathematical studies at the University. 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.

He studied the work of Croll, 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.
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. "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."
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.

Finally he published his theory in 1920 "Mathematische Theorie der durch Sonneneinstrahlung ausgelösten Wärmephänomene" (Mathematical theory of thermal phenomena caused by solar radiation).

Fig.1. Variations in the Earth's orbital parameters:
1. Eccentricity: the shape of the orbit around the sun.
2. Changes in obliquity: changes in the angle that Earth's axis makes with the plane of Earth's orbit.
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.
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).

In his theory he postulated:
- Glaciations are caused by variations of astronomical parameters
- The parameters influence the amount of solar energy on earth´s surface, especially during summer of the northern hemisphere (55°-65°N)
- It is possible to calculate these changes, and so calculate the climate in the past.

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.

Fig. 2. Figure from KÖPPEN & WEGENER 1924, where they correlated the calculated cycles to the know ice ages at that time.

Fig.3. 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.

References:

CHORLTON, W. (ed) (1985): Ice Ages (Planet Earth). Time-Life Books: 176
KÖPPEN, W. & WEGENER, A. (1924): Die Klimate der geologischen Vorzeit. Borntraeger, Berlin: 256

Resources:

NASA Earth Observatory: Milutin Milankovitch (1879 - 1958). Accessed 26.06.2010

Geology and Cyclicity

2010-06-06T09:11:00.000-07:00

1842, 5 years after Agassiz's "Discourse of Neuchatel", 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.
These cyclic factors influence the time and the energy density of solar radiation that reach earth from sun, causing cyclic climatic change. 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.
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.

Nevertheless the idea of the French mathematician was intriguing, and would influence later researchers.

In 1833, James Croll (1821-1890), son of a poor stonecutter of Perthshire, purchased a copy of the "Penny Magazine", 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; "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."

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.
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.
"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."
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.

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 "Climate and Time, in Their Geological Relations" in 1875.

Fig.1. Glacial and interglacial conditions when eccentricity is at its superior limit, from CROLL1875, frontispiece (from FLEMING 2006).

Fig.2. 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).

Geikie wrote about the work of Croll: "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."

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.
Geikie resumed: "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."

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: Geology and Cyclicity: Milankovitch´s idea.

Fig.3. Orbitally forced cyclic sedimentation in the Trubi Formation of Zanclean age at Scala dei Turchi, in the Rossello composite section (Sicily), that represents the template for the Pliocene Series.

Fig.4. 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.

References:

CHORLTON, W. (ed) (1985): Ice Ages (Planet Earth). Time-Life Books: 176
CROLL, J. (1875): Climate and Time, in their Geological Relations. A theory of secular changes of the Earth's Climate. D. Appleton and Company, New York: 630
FLEMING, J.R. (2006): James Croll in Context : The Encounter between Climate Dynamics and Geology in the Second Half of the Nineteenth Century. History of Meterology 3: 43 - 54

Megafauna Methane collapse

2010-05-24T09:08:00.000-07:00

There are lots of hypothesis 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 research that excluded humans as triggers for the Pleistocene extinction.

References

SMITH, F.A.; ELLIOTT, S.M.. & YONS, K. (2010): Methane emissions from extinct megafauna. Nature Geoscience. Published online: 23. May 2010: doi:10.1038/ngeo877

The hard life of being geologist - An introduction

2010-05-24T06:36:00.000-07:00

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.
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.
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. 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.

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 distance of 28 kilometres.

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.

Fig.1. "Geognosts" around 1800.

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.
The geologist Johann Czjzek in 1850 describes the requests to be a geologist: "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."

Fig.2. Some of the most famous geologists of the Geological Survey of Vienna (ca. 1860).

I will post these contributions parallel on a specific created blog: History of Geology.

References

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.

Mount St. Helens: 30 years of posteruption glacier development

2010-05-19T12:07:00.000-07:00

Fig.1. 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 Wikipedia).

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.

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 lahars, a part of the ice detritus also got embedded in the hot volcanic ash and evaporating suddenly, exploded and created a cratered landscape.

Fig.2. 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.

Prior to the eruption, 13 small glaciers with a combined surface area of about 5km2 existed on the volcano. From these glaciers the Loowit and Leschi glacier were completely destroyed, and the other glaciers suffered major mass lost.

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.

Fig.3. 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.

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.

The fast development and young age of various small rock glaciers inside the crater is also very intriguing.

References:

SCHILLING, S.P.; CARRARA, P.E.; THOMPSON, R.A. & IWATSUBO, E.Y. (2004): Posteruption glacier development within the crater of Mount St. Helens, Washington, USA. Quaternary Research 61: 325-329

They say that reading rocks is hard to do...

2010-05-17T12:31:00.000-07:00

Ever wonder how to tell if a rock layer is right-side-up or turned by mountain building? Dr. Richard Alley has the answers !

Te Pito Te Henua: Botanical Investigations from the navel of the world

2010-05-11T11:50:00.000-07:00

The collapse of the civilisation on Easter Island, or Rapa Nui in the native language, became very popular with the film "Rapa Nui" (1994) and the book of the American biologist Jared Diamond "Collapse - How societies choose to fail or survive" (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.

Fig.2. Map of Easter Island, or Rapa Nui / Te Pito Te Henua (Navel of the world) with the mentioned localities (after THOMSON 1891).

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.

Fig.3. 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).

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%).

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.
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.

There exist two major categories of hypothesis to explain the massive destruction of plant live and lose of species diversity on the island. Some hypothesis, 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.

Fig.4. 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).

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.

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.

Fig.5. 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).

Unfortunately interpretation of pollen diagrams can be very tricky.
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.

The tree species that produced the pollen on Rapa Nui is unknown. Pollen-morphological similarities exist to widespread species on pacific islands like Pritchardia, Cocos (coconut) and Jubaea chilensis (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 Juania australis, an endemic palm species on the Juan Fernández Islands.
Based on these remains finally the extinct species Paschalococos disperta, with dubious systematic affinities to recent tree species, was established. So the pollen calibration factor for the extinct species can not more obtained.

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.

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.
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.

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.

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.

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?
The available botanical data still don't allow an exclusion of one or the other scenario.

References:

THOMSON, W.J. (1891): Te Pito Te Henua, or Easter Island. Report of the National Museum 1888-89, Smithonian Institution. Washington
RULL, V.; CANELLAS-BOLTA, N.; SAEZ, A.; GIRALT, S.; PLA, S. & MARGALEF, O. (2010): Paleoecology of Easter Island: Evidence and uncertainties. Earth-Science Reviews 99:50-60 doi:10.1016/j.earscirev.2010.02.003
MANN, D.: EDWARDS, J.; CHASE, J.; BECK, W.; REANIER, R.; MASS, M.; FINNEY, B. & LORET, J. (2008): Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island). Quaternary Research 69:16-28 doi:10.1016/j.yqres.2007.10.009 Fulltext (pdf)

Introductory Picture from Wikipedia

The first geological map depicting loess (1865)

2010-05-09T09:35:00.000-07:00

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.*

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.
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. 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.

Fig.1. Carl Maria PAUL, Guido STACHE and in the middle Franz Ritter VON HAUER, the author of the first loess map of Central Europe.

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.
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.

Fig.2. The second edition of the General Geological General Map of the Austro-Hungarian 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 GAUDENYI & JOVANOVIC 2010.

Fig.3. Enlargement of the map in Fig.2.

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.

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. The Holocene formations were denominated "Alluvial" and included peat, lime tuff, quicksand and other formations summarized only as "Alluvial formations".
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.

Nevertheless it was one of the first maps which documented the extent of loess deposits in Europe and West Asia.

Fig.4. Modern map of loess distribution, from HAASE et al. 2007.

*The Student's Elements of Geology (1870): "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."

REFERENCES:

GAUDENYI, T. & JOVANOVIC, M. (2010): Franz Ritter von Hauer's work and one of the first loess map of Central Europe. Quaternary International. 10.1016/j.quaint.2010.04.008
HAASE, D., FINK, J., HAASE, G., RUSKE, R., PECSI, M., RICHTER, H., ALTERMANN, M., JÄGER, K. D. (2007): Loess in Europe - its spatial distribution based on a European Loess Map, scale 1:2,500,000. Quaternary Science Reviews 26 (9-10), 1301-1312

Biggest Beaver Dam Ever

2010-05-07T13:02:00.000-07:00

The actual location of the world longest beaver dam (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.
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.

Fig.1.

Arkology

2010-04-27T12:23:00.000-07:00

Evangelists claim 'Noah's Ark' discovery on Turkish mountain.

So my theory that it was/is hidden in area 51 is not more supported ?

Fig.1. With the wood of the ark you could make a lot of crates...

To be continued...

Volcano god angry - lets sacrifice the geologist

2010-04-22T12:40:00.000-07:00

Natural events or presumed catastrophes will always lure from their hideouts religious fanatics and other self declared experts.

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).
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: "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".

Fig.1. Cartoon from The Perry Bible Fellowship

But this is not even the dumbest opinion on the eruption:
The NATO was also portrayed as guilty, because the military exercise "Brilliant Mariner " 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.
Funnier is the alleged connection of the Icelandic volcano to a possible extraterrestrial invasion, Agent Spooky-Mulder would be pleased.

Meanwhile the German bio-physician Dieter Broers is cited in the German tabloid BILD: “NASA images show just one day before the eruption the largest solar flare in 15 years. - He is certain: The earth is heading to a doomsday triggered by the Sun in 2012.”

The tabloid, notorious known for its approach to science, continues with a list of other “incredible“explanations:

The German author Hartwig Hausdorf, dedicated “mystery researcher”, postulates a connection between the American HAARP-project 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.

Hydrobiologist and journalist Edgar L. Gärtner got the simplest of all explanations “There is no ash-cloud”. The entire story is only a conspiracy and a deflection strategy to prepare a terror attack of incredible proportions.
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 ?

Fig.2. Thor battles the terrible Jörmungandr ( Heinrich Füssli 1788).

Don´t even bother to ask a geologist... 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.

Accretionary Wedge 24: Heroes VS Cartoons

2010-04-20T12:52:00.000-07:00

Callan Bentley at Mountain Beltway will be hosting the next edition of The Accretionary Wedge and he is searching heroic earth scientists.

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.
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.
Let's also remember the words of the theoretical physicist Philippe Blanchard

"The scientist should take the science seriously, but they should not take themselves to seriously."

People that propose revolutionary ideas, ahead of their time, often get misunderstand, even attacked verbally and ridiculed. William Smith 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 Charles Darwin and Thomas Henry Huxley are today part of history.
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. 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.
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. 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.

The first geologists had to face many prejudices and hostilities, like James Hutton (1726-1797), facing the many critics of his ideas on deep time and rock formations. 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.

Fig.2. "Awful Changes.", see also the Ichthyosaurus installment at ART evolved.

The prominent "Professor Ichthyosaurus" 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.
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.

In the other drawings 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).
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.

Fig.3. De la Beche´s cartoon of 1830-1833 mocking the effects of present causes. The cartoon is entitled "Cause and Effect".

The child is peeing into the huge valley and a caption has his nurse exclaiming, 'Bless the baby! What a valley he have made.!!!'

On the 24 July of 1837 the Swiss geologist Agassiz 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. "O Sancte de Saussure, ora pro nobis!" - O holy de Saussure, 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.

Agassiz introduced with his former mentor Buckland in the autumn of 1840 the glacial theory to the British Isles.
Professor Buckland, 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. 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.

Fig.4. Costumes of the Glacier.

The cartoon sketch that he scratched/draw of the Professor, titled "Costumes of the Glaciers", shows Buckland dressed for fieldwork. The numerous captions are difficult to read, but the lines at Buckland's feet are noted to be "Prodigious Glacial Scratches" produced by "the motions of an IMMENSE BODY, not allow to change its course upon Slight Resistance" (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 "Map of Ancient Glaciers". 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.

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.
What I choose, are only two examples and theories, and many others were worth to be told, 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.

We are only humans - and maybe that’ s the most important teaching that cartoons can give to us.

BIBLIOGRAPHY:
BROWNE, J. (2001): Darwin in Caricature: A Study in the Popularisation and Dissemination of Evolution. Proceedings of the American Philosophical Society 145(4): 496-509
CLARY, M.R. & WANDERSEE, J.H. (2010): Scientific Caricatures in the Earth Science Classroom: An Alternative Assessment for Meaningful Science Learning. Sci & Educ 19:21-37
GORDON, E.O. (1894): The Life and Correspondence of William Buckland. John Murray, London
LEEDER, M.R: (1998): Lyell's Principles of Geology: foundations of sedimentology. Geological Society, London, Special Publications 143: 95-110
MACDOUGALL, D. (2004): Frozen Earth - The once and future story of Ice Ages. University of California Press, Berkely-Los Angels.
RUDWlCK, M. S. (1975): Caricature as Source for the History of Science: DE LA BECHE'S Anti-Lyellian Sketches of 1831. Isis, Vol. 66 (234): 534--560
RUDWICK, M.J.S. (2005): Bursting the Limits of Time. The Reconstruction of Geohistory in the Age of Revolution. The University of Chicago Press.

Introduction Image: The Trilobite, cartoon from The Punch 1885

Tephrostratigraphy

2010-04-16T11:02:00.000-07:00

The ongoing eruption of the Icelandic volcano Eyjafjallajokull caused much interest in the geoblogosphere (Italy, Portugal, U.S.A and Outside, geologists - but also paleontologists get interested, and of course magmaliceous volcanologists here and here) 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).

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. 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.

Fig.1. 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.

So ash deposits, or Tephra, have very special features:

-they are erupted over very short time periods, geologically speaking, usually a matter of only hours or days to perhaps weeks or months

-they can be spread widely over land and sea to form a thin blanket that (unless reworked) has the same age wherever it occurs.

- The volcanic minerals can be dated by radiometric methods (Argon40-Argon39 for example)

- 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.

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.
After the first pioneering work, studies of tephra layers spread in the 1920s and 1930s in New Zealand, Japan, Iceland, South America and USA.

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 Laacher See Tephra, the (ex-)Thera volcano in the Mediterranean Sea.

Fig.2. 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 recent ash-plumes over Europe (and here).

Fig.2. (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).

REFERNCES:
ALLOWAY, B.V. et al. (2007): Tephrochronology. In (ed): ELIAS, S.A. (2006): Encyclopedia of quaternary science. Elsevier
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

Taphonomy of hominid sites, or what geology can tell us about our origins

2010-04-15T12:00:00.001-07:00

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.

Fig.1. Mentioned hominid bearing sites, Aramis near the river Awash in Ethiopia and Malapa in South Africa.

The presentation to the public of Ardipithecus ramidus, 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 Australopithecus sediba from South Africa.
But both described species are only a part of the recuperated evidence (in case of A. ramidus nearly 150.000 bone fragments), behind A. ramidus there lie 15 years of research, behind A. sediba 2 years - the paleontological and geological results of both sites shamefully received little attention in the mass media.
But the careful collection and examination of animal and plant fragments, and the geological framework, was rarely well documented as by these two discoveries.

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. Then, in 1925, the discovery of the first Australopithecus species, considered a early hominid, by Raymond Dart seemed to give further clues of human evolution.
The associated faunal remains showed that Australopithecus 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.

But the sediments and the paleontological content of the Lower Aramis Member (Sagantole Formation) at Aramis provided evidence that Ar. ramidus 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.

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. 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.
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.
The recovered bones of birds and mammals came from species living in, or associated with, closed forest or shrublands. One of the common larger mammals found associated with Ardipithecus is the spiral-horned antelope, or kudu (Tragelaphus).

Fig.2. A not so scientific reconstruction of a possible hominid habitat.

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.
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 Ardipithecus is also similar to that of Tragelaphus, indicating little dietary intake of grass, and supporting the reconstruction that the animal lived predominately in the forest.

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.

Fig.3. after WHITE et al.2009. Isotopic signature of fossil enamel from the Aramis Member.

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?

Let's see what the rocks can tell us. The two skeletons of Australopithecus sediba were discovered in cave infillings of the karst landscape 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 Equus sp.
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. 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.

Fig.4. Geological map of the Malapa site, after DIRKS et al. 2010. The fossils of hominids where interbedded in facies D. The underlying flowstone was also dated by U-Pb on an age of ca. 2 Ma.

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.

These new data and the combination of different scientific approaches questions old certainties. The case of Ardipithecus suggests that the anatomy and behaviour of early hominids did not evolve in response to open savanna or mosaic settings.
In the case of A. sediba the geology tell us how hominids become fossilised and where we must search for them. The fossils found with A. sediba 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.

REFERENCES:
BERGER et al. (2010): Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. Science, 328: 195-204
DIRKS et al. (2010): Geological Setting and Age of Australopithecus sediba from Southern Africa. Science, 328: 205-208
LOUCHART et al. (2009): Taphonomic, Avian, and Small-Vertebrate Indicators of Ardipithecus ramidus Habitat. Science 326: 66-66e4: DOI 10.1126/science.1175823
WHITE et al. (2009): Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus. Science 326: 67-93; DOI 10.1126/science.1175822
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

Peru glacier breaks up, causes tsunami

2010-04-13T12:56:00.000-07:00

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 msnbc

Landslide in South Tyrol causes train derailment

2010-04-12T08:42:00.001-07:00

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).

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.

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.

Fig.1. 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 (Product of the Autonomous Province of Bozen/Bolzano - South Tyrol)

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.

MAMOHTEHKA MAMA

2010-04-04T04:05:00.000-07:00

"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 extinction and started the quest for his mom search (found on Siberian Mammoth).

Accretionary Wedge #23: That is not dead which can eternal lie

2010-03-27T06:59:00.000-07:00

The March 2010 Accretionary Wedge is being hosted by Ed at Geology Happens, and here's the proposed theme:

"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?"

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:

"That is not dead which can eternal lie,
And with strange aeons, even death may die"
H.P. Lovecraft (1890-1937)

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.
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.
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.
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.

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?

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).

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.

Fig.1. 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.

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.

A connection of the rock glacier with the glacier high stand of the alpine Little Ice Age is supported in part by lichenometry 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.

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.

Fig.2. Outcrop, GeoRADAR measurements and soundings showed that the peat is pretty deep, up to 3m.

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).
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 Rieserferner mountain group, so such records are not rare, and have much potential for future research on the Holocene history of the Southeast-Alps.

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.

And because finally the wintertime is over, I hopefully soon will go back to the rock glacier and dare to interfere in his sleep...

Fig.3. Peat layers in transition to grey mud and pebbles.

REFERENCES:
BORTENSCHLAGER, S. (1984): Beiträge zur Vegetationsgeschichte Tirols I. Inneres Ötztal und unteres Inntal. Berichte des Naturwissenschaftlich-Medizinischen Vereins in Innsbruck. 71, 19 - 56.

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
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
HUMLUM, O. (1996): Origin of Rock Glaciers: Observations from Mellemfjord, Disko Island, Central West Greenland. Permafrost and Periglacial Processes 7: 361-380
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
PALACIOS, D. & VAZQUEZSELEM, L. (1996): Geomorphic effects of the retreat of Jamapa glacier, Pico de Orizaba volcano (Mexico). Geografiska Annaler 78A(1): 19-34
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 Glacier, Blenio Valley (Ticino, Southern Swiss Alps): Implications for Rock Glacier, Treeline and Climate History. Permafrost and Periglac. Process. 21: 90-96

Understanding Climate’s Influence on Human Evolution

2010-03-25T14:30:00.000-07:00

Free e-book

Tofane Rock glacier

2010-03-11T12:42:00.000-08:00

An active superimpose a relict rock glacier in the Tofane mountain group (South-East Dolomites 46°32``0`N 12°3``0E):

Fig.1

Cold War in the 21st century

2010-03-10T11:50:00.000-08:00

The principle behind the system of the "Cold War" is simple: you have to possess a weapon stronger then your adversary.

So it's no wonder when governments all over the world are secretly constructing weapons with alien technology - or at least that is what the conspiracy fanatics all over the net are claiming.

Two recent examples: The EU will get the "Black Hole Gun", unfortunately for the LHC opponents the Constitutional Court judges in Karlsruhe (Germany) are obviously not afraid of black holes - they rejected a lawsuit against the use of the particle accelerator for scientific research.

But in case: it's only self defence, because the U.S. use(d) the "HAARP Death ray" to cause earthquakes and take over the world.

Picture reference

"On the Distribution of Erratic Boulders..." by C. Darwin

2010-03-09T12:09:00.000-08:00

The papers submitted by C. Darwin to the Geological Society are available online Darwin´s Papers:

C. Darwin
'On the Transportal of Erratic Boulders from a lower to a higher level'
Quarterly Journal of the Geological Society 4: 315-323.
http://jgslegacy.lyellcollection.org/cgi/reprint/4/1-2/315

C. Darwin
'XXVII.—On the Distribution of the Erratic Boulders and on the Contemporaneous Unstratified Deposits of South America'
Transactions of the Geological Society of London s2-6: 415-431.
http://trn.lyellcollection.org/cgi/reprint/s2-6/2/415

The Dolomite Mountains - The stony heart of earth

2010-03-03T12:14:00.000-08:00

The german edition of the "National Geographic" magazine got an interesting cover story in the march issue: "The Dolomite Mountains - The stony heart of the earth."

Fig.1. Cover of National Geographic Deutschland

Fig.2. The peaks of Cisles

Landslide of Leisach (Austria)

2010-02-22T12:48:00.000-08:00

A landslide near the village of Leisach (East-Tyrol, Austria;46°48`36`` N / 12°45`02`` E), occured in the night between the 19. and 20. february, has dammed up the river Drau and buried the street and trainrails between Italy and Austria. The landslide is 100m wide and 10m thick.
I´m expecting more to come in the next weeks and months...

Fig.1. Foto/Copyright: Robert Gutwenger Lienz (source)

Maierato landslide-aftermath

2010-02-17T11:45:00.000-08:00

Fig.1. The Maierato-landslide today. LINK and LINK2

Landslide in Calabria

2010-02-15T12:37:00.000-08:00

Landslide in Calabria (South-Italy), town of Maierato (38°42`29``N 16°11`33``E) - 15.02.2010:

UPDATE 17.02.2010: Video of landslide-aftermath

UPDATE 16.02.2010: Mass evacuation of all 2.300 inhabitants of Maierato, a town in the province of Vibo Valentia: an entire side of the mountain which is located near the town collapsed yesterday morning and caused a huge landslide. The landslide - says the mayor Sergio Rizzo - threatens an important part of town and we have unfavourable weather conditions, so we decided not to risk. The first 300 people were evacuated from their homes yesterday evening, but this morning began the evacuation of the entire town. Rainy weather and resulting mass wasting has caused problems also in other parts of Calabria and Sicily.

Fig.2. Carta Geologica della Calabria Foglio 241 1:25.000 (click to enlarge)

The landslide developed in Pliocene-Miocene marls and argillaceous deposits, and showed first signs of reactivation 10 days ago.

Fig.1. Extract of the geological map of Maierato, by Dr. E. Bonino. M= Miocene, P= Pliocene, d= recent deposits. Area of landslide red contour. See also this WebGIS application.

UPDATE: Map of MAIERATO with preliminary risk zonation and delimination of landslides

VIDEO (16.10.2010)

VIDEO released 15.02.2010:

Sea-Level Highstand disproves ice-age CO2 connection?

2010-02-12T02:43:00.000-08:00

The ice ages on Earth could be influenced by CO2 levels differently than previously believed. The study of speleotherms in the cave of Vallgornera situated on the Spanish island of Mallorca revealed that the polar caps were as small as today 81,000 years ago - despite lower CO2 levels.
A team of scientists of the University of Iowa has studied aragonitic and calcitic mineral deposits from five caverns situated; depending of the sea level - itself varying by the amount of “captured” water in ice caps up to 130m - the caves were inundated and different mineralogical deposition occurred.

The dated samples suggest that the sea level around 81,000 years ago was about a meter above the current value. "We have reconstructed the sea level with really high precision," says researcher Doral to the German newspaper “SPIEGEL ONLINE”.Co-author Bogdan Onac from the University of South Florida explains that Mallorca is ideal for this kind of research because tectonically stable and the observed variations should be “true” variations of sea level, not falsified by geological movements or isostatic rebound.

If the sea level 81,000 years ago was actually where the researchers suggest, an interesting problem arises: it doesn’t support the calculated 100.000-year cycle of glacial advances. Also it contradicts the direct ice-CO2 connections - despite low CO2 concentrations, and weaker greenhouse effect, the ice caps on earth were not as great as previously tough, and in dimensions comparable to modern conditions.

So are climate denialists right, and is there no such thing as anthropogenic greenhouse effect?

No, the authors want to take the results in a scientific context: the research doesn’t make claims about the global temperature during this time, only about the possible ice volume, and the amount of ice is not only controlled by temperature, but also for example by insolation of the sun, stronger 80.000 years ago then today. "What happened 80,000 years ago, is not the same as what happened today," said Onac.

REFERENCES:

DORALE et al. (2010): Sea-Level Highstand 81,000 Years Ago in Mallorca. Science Vol.327(5967): 860 - 863

Climate hoax

2010-01-08T12:58:00.000-08:00

What if climate change is the greatest hoax ever archieved:

from Atheist Movies

The day after tomorrow ?

2010-01-08T12:21:00.000-08:00

Snow across Great Britain

... anyway - Europe is still inhabited...

Martian spillway

2010-01-06T08:19:00.000-08:00

On images of the Mars Reconnaissance Orbiter -MRO- a british research team has discovered possible "spillway" of ancient martian lakes.
The pits in the equatorial region of Ares Vallis were first explained as remains of evaporating water ice, but the discovered channels seems to connect different basins, much more like t hermokarst- lakes connected by small rivers. The estimated age of the features is with only 3 billion years surprisingly young.

References:

Altes Seensystem auf dem Mars entdeckt. SpiegelOnline 06.01.2010
WARNER et al. (2009): Hesperian equatorial thermokarst lakes in Ares Vallis as evidence for transient warm conditions on Mars. Geology 38:71-74

Did volcanoes kill the Mammoth?

2010-01-03T08:19:00.000-08:00

The cause(s) of the Pleistocene Megafauna extinction is(are) still unclear. Various explanations were proposed, ranging from human activity (hunting or disease spreading) to climate change or sea level rise, and since the last year, a possible extraterrestrial impact. But an important factor until now was less considered - volcanism. Volcanoes can have an impact on climate and ecosystems, for example ash can block the sunlight, and poison large territories.
A short, but intriguing paper by Dmitry A. Rubam summarizes and analyze the idea that intensified volcanism at the end of the last glacial period maybe triggered the biotic crisis. The volcanic activity of the last 50.000 years can be reconstructed by ash layers and geochemistry of ice cores, and compared to extinction patterns on the different continents.

The data show a higher frequency of eruptions near the end of the Pleistocene, but the demise of the fauna doesn’t coincide exactly with this period, especially the extinction in Australia happened previously. However it is possible that only a certain "sum" of volcanic events finally triggers a biotic response.

Fig. 1 - Temporal relationships between the volcanic eruption frequency and extinction events. Volcanism intensifications are highlighted by grey circles (from RUBAN 2009).

The preliminary results show that intensified volcanism cannot provide a better explanation of the crisis than other triggers; however none of the possible triggers alone provide an ultimate explanation.

The evidence makes it plausible, that an intensification of volcanism just before the end of the Pleistocene was able at least to contribute to the extinction of megafauna in America and Eurasia.

References:
RUBAN, D.A. (2009): A possible contribution of volcanism to the end-Pleistocene megafaunal etinction. Natura Nascosta 39:26-32

The Future Of Mankind

2009-12-08T12:50:00.000-08:00

Carl Sagan Reflects:

Did the Pleistocene Megafauna and Dinosaurs Live at the Same Time?

2009-12-04T11:34:00.000-08:00

A national science foundation is a public organization with the task to perform and promote research activities and scientific knowledge and its applications in our daily live.

If you had to promote earth science and biology, what would you do?

Would you finance the conservation of one of the largest dinosaur ichnosites in the world - at moment abandonet and slowly decaying, would you promote research on Pleistocene to Pliocene sediments full of remains of marine and terrestrial mammals, - yet not full understand, would you place under protection nesting sites of Triassic reptiles - destroid to build a hicking trail, would you install signs to draw attention to geological features - hidden under rubbish, would you promote teaching of science in school?

The Italian science foundation - Consiglio Nazionale delle Ricerche (CNR) decided to promote, funding and publish a book about a workshop hold in February 2009 about the scientific demise of evolution, with the same contributors of this second congress (November 2009):

"The Scientific Impossibility of Evolution"

Dominique Tassot: Introduction
Guy Berthault: Experiments in Stratification do not support the Theory of Evolution
Thomas Seiler: The Second Law of Thermodynamics and Evolution
Josef Holzschuh: Recent C-14 Dating of Megafauna and Dinosaur Fossil Collagen
Jean de Pontcharra: Are Radio-dating Methods reliable?
Maciej Giertych: Impact of Research on Race Formation and Mutations on the Theory of Evolution

What would you do ?

What would Mr. Deity say?

Dating catastrophes

2009-11-30T13:09:00.001-08:00

Methods for dating mass-movement events earthquakes, volcanic eruptions and other geological hazards comprise a wide range of methods, historic, radiometric, stratigraphic and biological. For example Carbon-14 dating, applicable when the moving mass incorporated vegetation, or other radioactive elements that decay with time, surface dating of freshly exposed boulders by cosmogenic isotopes, dating of sediments by thermoluminescence, dendrochronology or lichenometry and for historic times written records or witness accounts.

Historical references are the most reliable sources for reconstructing the temporal distribution of catastrophes, especially for the last few centuries. Going further back in time, medieval time and antiquity ,the record gets poorer and more inexact. And for prehistoric time we miss descriptions of this kinds, or did we?

Considering (pre-)historic events, the oral tradition and legends all over world maybe represent first efforts to record and explain such phenomena, even if we have to be cautious, myths in geology can only be a supplementary help, not a fact, and much is left by the interpretation of stories by the compiler. Nevertheless knowing some old stories about the landscape can not be so bad for a geologist.

In the area of Seattle, Washington, at least five sites with landslide deposits or large boulders are known by local legends of the Duwamish people to be haunted by a´yahos. A´yahos are spirits with the body of a serpent and the antlers and forelegs of a deer. Old folks used to say not to look directly to an a´yahos because it could shake the ground or turn people to stone.

Non-Salish Cascadia Native representation of two -headed snakes, likely to represent spirits comparable with a´yahous. Quileute ceremonial representation of t´abale, a vicious guardian spirit on the northwestern Washington coast (from LUDWIN et al. 2007).

In 1990s geophysical investigations revealed that the area of Seattle is passed by a fault system and at least 1100 years ago an earthquake hit the entire zone- triggering mass movement all over the landscape.

Reconstructed "events" by means of oral tradition and mythological conventions.
Date range estimates used the following assumptions: a 'generation' is no fewer than 15 and no more than 40 years, events before age 5 are not remembered. the maximum lifespan is 100 years, flood survivors were 'old' when seen. and an 'old' person is at least 40. (from LUDWIN et al. 2007).

The bay of Lituya situated in Alaska is a narrow, only 2 kilometres broad, but 11 long bay open to the Pacific Ocean. The native Tlingit Indians tell that in a cavern, deep underground, lives a demon, similar in appearance to a great toad or frog. If someone dares to disturb the tranquillity of the bay, the demon will rip apart the sea and the earth and catch the intruder and transmute him to a bear.

Behind the anger of demons maybe an exceptional (yet undated) geological event hides, as a recent example shows:
On the 9th July 1958 an earthquake produced by a fault nearby triggered a rockfall, with an estimated volume of 40 million cubic metres and a weight of 90 million tons that felt from a height of 1000m in the water. The resulting wave reached a height of 524, the highest ever (human-) documented wave.

The Yurok Indians, once native in the Cascade Range, tell about the creation of the world by "earthquake" and "thunder":

And from there, earthquakes and thunder went south. They first went to the south and let fall the ground. In rapid succession, there was an earthquake and another earthquake, and then the water filled the place. "This is what brings people to live", said earthquake. "They would have no food, if there were not place for the creatures of the sea, to live in it. From here, they will obtain what they need to live, where prairie has become water."

During excavation in today's marshes along the coast of the region a series of sand and peat layers was discovered. Such deposits are formed when the coast is flooded by a tsunami, and sand is deposited, overlying an ancient soil. The discovery proves that this area in the past has been repeatedly devastated by tsunamis.

References:

FRITZ, H.M., HAGER, W.H., MINOR, H-E. (2001): Lituya Bay Case: Rockslide impact and wave run-up. - Science of Tsunami Hazards 19(1), 3-38.
LUDWIN, R.S. & SMITS, G.J. (2007): Folklore and earthquakes: Native American oral traditions from Cascadia compared with written traditions from Japan. From PICCARDI, L. & MASSE, W.B: (eds): Myth and Geology. Geological Society, London, Special Publications, 273: 67-94
LANG, A.; MOYA, J.; COROMINAS, J.; SCHROTT, L. & DIKAU, R. (1999): Classic and new dating methods for assessing the temporal occurrence of mass movements. Geomorphology 30:33-52

An Animal Fable from the Upper Cretaceous

2009-11-29T10:56:00.000-08:00

The modern tale "Homchen - ein Tiermärchen aus der oberen Kreidezeit" (Homchen - An Animal Fable from the Upper Cretaceous), was published in 1902 by the German author Kurd Laßwitz (1848-1919), considered a founder of the German science-fiction movement.

Homchen is a highly evolved marsupial of the Kala-tribe, living in a world dominated by the great lizards. In a world ruled by ignorance and oppression, Homchen rebels against the saurian warlords, and is banned from the society of mammals. He then decide to search the red snake, creator of the reptilian world, but the dinosaurs, and especially the "dainty beak's", high priests of the red snake, try to stop him at any costs.

A sketch by Laßwitz of Homchen of the Kala tribe - clearly inspired by a Koala. Laßwitz considered human evolution as a straight forward process from rodents to marsupials to placental mammals and finally humans.

"You know what the red serpent will do, if you don't obey? He will swallow the sun, until it will be small and cold. And the day will be like the night, and all water will be frozen. The trees lost their leaves and the grass will be covered by white ash, so nobody will find something to eat. The reptiles that didn't starve, will be suffer great cold, and finally they will be unable to move. Then the animals of the night will rise, protect by their fur, and they will scratch the eyes from your faces, like Kala did to the hollow-bone. The mammals will eaten your flesh, and your bone they will throw against the sun, until it fall from sky and the eternal night begin."

Mission CryoSat-2

2009-11-28T10:03:00.000-08:00

Source: Project Cryosat and Cryosat-2

The ice in the polar regions play a crucial role in earths climate, but the quantification of the ice and measuring it's change trough time is difficult.
Satellite images provide a good tool to determinate the area, but the thickness can only measured on single points by costly drilling trough the ice. New generation satellites, like the American "Icesat" use RADAR technology to determinate precisely the ice thickness, but snow cover and water are still a problem, and can distort the measurements. After the failure tof the European Space Agency to send a new generation satellite - Cryosat (crashed only few seconds after the start in 2005)- in the orbit, now his brother - Cryosat2- is almost ready.

In December the satellite will leave Munich (Germany) to be transported to the Kazakhstan spaceport Baikonur, from where it will be send in February 2010 with a modified rocket (a former atom weapon carrying Dnepr model) in space.
With a new RADAR-altimeter ("Siral") Cryosat2 will take 20.000 measurements per second in the next three years with an unequalled precision, and be able to determinate changes of thickness in ice of only few centimetres.

Meanwhile reports of Canadian researches under David Barber (University of Manitoba) confirm the receding trend of the ice cover in the Arctic. On 12 September 2009 the ice covered 5,1 million square kilometres, only 2007 and 2008 the area was lesser compared to the mean value of the 30 years of satellite measurements. Compared to the long term observed between 1979 and 2000, the remaining actual ice cover is also 70% of the former area, the area of long lasting ice diminished from 90 to 17%.
Not only the area is declining, also the thickness is inferior, in some areas the thickness diminished from 10m to 2m. The thinner ice is more fragile, and can not resist wave movements or storms.

Biologists are concerned about the status of the polar bear, with a valued population of 25.000 animals: the ice is in vast regions to thin to be used by the animals to hunt, and the sea freeze later in the year.
In the area of Churchill, in the Canadian province of Manitoba ,the biologist Ian Sirling (Canadian Wildlife Service) observed a possible related fact - an increasing of cannibalism events from elder on younger animals.

150 years

2009-11-24T12:52:00.000-08:00

An abstract still evolving...

Darwin's rat and other strange mammals

2009-11-22T07:13:00.000-08:00

"I had no idea at the time, to what kind of animal these remains belonged".

C. Darwin 1839

During the first two years of his voyage aboard HMS Beagle, Charles Darwin collected a considerable number of fossil mammals from various localities in Argentina and Uruguay. He recovered his first fossils at Punta Alta on September 23, 1832, and the last two years later at Puerto San Julián.
The fossils were packaged and sent to his former mentor the botanist/geologist John Stevens Henslow, deposited in the Royal College of Surgeons in London, and finally studied and named by Richard Owen between 1837 and 1845. Based on the fossil material Owen described a variety of Pleistocene mammals, including Equus curvidens, Glossotherium sp., Macrauchenia patachonica, Mylodon darwini, Scelidotherium leptocephalum and Toxodon platensis.

Unfortunately during April 10 and 11.1941 the paleontological collection of the Royal College was heavenly damaged by bombardment, almost 95% of the collection got lost. Beginning in 1946 the remaining material was transferred to the Natural History Museum in London, where it is still housed.

Fossils were known in South America since before the Spanish conquistadores, but interpreted as the remains of mythical creatures or giants annihilated by the gods. In 1774 the English Jesuit Thomas Falkner wrote:
"On the banks of the River Carcarania, or Tercero, about three or four leagues before it enters into the Parana, are found great numbers of bones, of an extraordinary bigness, which seem human. There are some greater and some less, as if they were of persons of different ages. I have seen thigh-bones, ribs, breast-bones, and pieces of skulls. I have also seen teeth, and particularly some grinders which were three inches in diameter at the base. These bones (as I have been informed) are likewise found on the banks of the Rivers Parana and Paraguay, as likewise in Peru. The Indian Historian, Garcilasso de la Vega Inga, makes mention of these bones in Peru, and tells us that the Indians have a tradition, that giants formerly inhabited those countries, and were destroyed by God for the crime of sodomy. I myself found the shell of an animal, composed of little hexagonal bones, each bone an inch in diameter at least; and the shell was near three yards over. It seemed in all respects, except it's size, to be the upper part of the shell of the armadillo; which, in these times, is not above a span in breadth."

22 years later the French naturalist George Cuvier published the first scientific work on a fossil South American mammal, and named it the giant sloth Megatherium americanum. In 1806 Cuvier described preliminary three proboscidean types, attributing them to the genus Mastodon. After these first investigations, there was almost no further research, in 1838 Owen wrote in his opening paragraph on his work on the fossil mammals collected by Darwin:
"It may be expected that the description of the osseous remains of extinct Mammalia, which rank amongst the most interesting results of Mr. Darwin's researches in South America, should be preceded by some account of the fossil mammiferous animals which have been previously discovered in that Continent. The results of such a retrospect are, however, necessarily comprised in a very brief statement; for the South American relics of extinct Mammalia, hitherto described, are limited, so far as I know, to three species of Mastodon, and the gigantic Megatherium."

The young Darwin got some of the first fossil determination wrong, so he attributed found osteoderms (regarded by Owen to belong to the giant "armadillo" Glyptodon) to Megatherium, following a reconstruction by Cuvier of an armoured ground sloth, and molars of Toxodon as remains of a giant rodent (but even Owen admitted that these teeth's bear a certain resemblance to those of rodents).
Owen by his part got the general relationship of this mammals incorrect, attributing some genera closer to existing animal-groups then they were in fact.
Influenced by the proposal of Owen, Darwin got convicted that "The most important result of this discovery, is the confirmation of the law that existing animals have a close relation in form with extinct species." (1839), surely a further clue for Darwin that species are not isolated and immutable in time.

Ironically in the error of Darwin there is a ray of truth, toxodonts are today considered highly derived native South American ungulates, distantly related phylogenetically to rodents and guanacos, whereas the large glyptodonts are not the ancestors of armadillos, but to the contrary, the latter are antecedent to the former.

Frederick Waddy: Richard Owen "Riding His Hobby" (1873)

References:

FERNICOLA; VIZCAINO & DE IULIIS (2009): The fossil mammals collected by Charles Darwin in South America during his travels on board the HMS Beagle. Revista de la Asociacon Geologica Argentina. 64(1): 147-159

Extinctions & Excrements

2009-11-20T12:35:00.001-08:00

"dal letame nascono i fior
dai diamanti non nasce niente"
From dung flowers are born
From diamonds nothing comes
"Via del Campo", Fabrizio de André (Italian poet-musician)

Until 20.000 years ago North America showed a biodiversity of large mammals comparable with modern Africa, if not greater. 10.000 years later 34 genera with animal-species weighing more than a ton were extinct.

The extinction of the Pleistocene Megafauna is still an unsolved mystery. The proposed hypothesis range from overkill by human hunters to a meteor impact and climate change at the end of the last glacial maximum. Geologically speaking it happened suddenly, but a new study now maybe can date more precisely the extinction pattern and duration, using an unusual data source - fossil excrements and the inhabitants of this "biotope".

In 2005 and 2006 sediment cores with a complessive length of 11,7m were taken from Appleman Lake and compared with other cores of lakes in the U.S. State of Indiana.
Thirteen wood, pollen and charcoal samples, recovered from the lacustrine sediments, were dated by radiocarbon method on ages between 7.000 and 14.000 yr BP and used interpolate an age-depth model of the core.

The fungus-genus Sporomiella lives on animal dung and the spores have to pass the digestive tract of large herbivores to germinate. The spores can also accumulate in sediments along with other micro- and macrofossils like pollen and charcoal, so the presence of the fossil spores in sediments correlates with the amount of excrements - "Lots of dung means lots of spores" (JOHNSON 2009), and the amount of dung can give a hind to extrapolate the size of the population of herbivorous animals like mastodon or mammoth.

The timing of the Sporomiella decline and the first major charcoal peak are well constrained by two dates between 14.6 and 14.7ka. The wood pollen (Quercus and Pinus) increases between 10.7 and 12.2 ka.

Figure from GILL et al. 2009: Appleman Lake time series for (A to F) percent pollen abundances of selected taxa (NAP, nonarboreal pollen), (G) Sporormiella and (I) charcoal counts.

Applying this method, Gill et al. found that the amount of spores first decreases slowly, and only in 14.800 years old sediments the number of spores decreases significantly. To old for the proposed impact, and also to old for a climatic or environmental change - vegetation change, interpolated from the pollen assemblage, namely happens only after the faunal demise, and is more probable caused by the extinction of large herbivore, then the cause of extinction.

The greatest impact of humans - in form of the Clovis Culture - on the Pleistocene landscape in North American was supposed in a time interval between 13.330 and 12.900 years ago. The new data predates the Clovis, nevertheless archaeological findings support a lesser tool specialised pre-Clovis culture in the time interval of the Megafauna collapse, so human influence could not be ruled completely out.

Figure from JOHNSON 2009.

The changing environment after the Megafauna collapse, from an open savanna with scattered trees to a spruce-broadleaf woodland, was the result of ceased pasture of shrubs and trees by Mammoth and Co. The expansion of woodlands is also supported by a larger amount of charcoal in the sediments, from time to time the woodlands caught fire, and the ash was eroded, transported and finally deposited in the examined lakes.

Even if the new method con not give us the definitive answer, at least it's provide some new data to better understand the temporal progress and the environmental change of the late Pleistocene extinction event.

References:

GILL et al. (2009): Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America. Science 326: 1100-1103 http://www.sciencemag.org/cgi/content/abstract/326/5956/1100

GILL et al. (2009): Supporting Online Material for Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America. Science 326. www.sciencemag.org/cgi/content/full/326/5956/1100/DC1

JOHNSON (2009): Megafaunal Decline and Fall. Science 326: 1072 - 1073. http://www.sciencemag.org/cgi/content/short/326/5956/1072

Interview to Dr. Jacquelyn Gill by the Canadian Broadcast: mp3 (4MB)

--------- Thanks to Ole Nielson for linking to the post----------

Cool Artiodactyls

2009-11-17T12:50:00.000-08:00

Islands seem to have own rules concerning evolution, forming unusual animals like dwarfing elephants and gigantic rats. But islands are in fact unusual habitats with limited resources and so available energy. To survive special adaptations are necessary to economize this energy. Ectotherm vertebrates, like reptiles, are specialists in coping with low levels of available energy, but doing so these animals display an inconstant growth - with times of low or ceasing growth when conditions are unfavourable. Endotherm animals, like mammals have high and steady growth rates, but the necessity of constant food - energy - input, on a confined island a possible problem. But the Pliocene-Pleistocene "cave goat" or "Mouse-goat" Myotragus balearicus after a new study by Köhler & Moyá seems to have combined the best parts of being reptile and mammal together.

Myotragus balearicus (wikipedia)

Studying fossil material of this extinct species, the researchers have noted in bone transects cyclic LAGs - lines of arrested growth. This pattern was until now unknown in mammal bones, even if single lines were known in cervids, the physiology of Myotragus seems to have used this strategy repeatedly. Myotragus grew at slow and variable rates; growth could also be arrested completely to save precious energy. With this strategy the species managed to survive on the resource poor island of Majorca for more then 5,2 million years, until humans colonized the island, and, like many times before and after, forced the species to extinction.

The mystery of Darwin's wolf

2009-11-15T12:33:00.001-08:00

During the voyage of the Beagle, (just) one (other) of the puzzling observations by Charles Darwin was the presence of a large canid on the remote Falkland Islands - as only native mammal species. On the two islands, Darwin recognized differences between the East Falkland and West Falkland wolves (Dusicyon australis), a further clue for Darwin that species are not fixed entities.

Illustration of Dusicyon culpaeus from Zoology of the Voyage of H.M.S. Beagle (source wikipedia).

Ever since the Falklands wolf was described by Darwin, the biological origin of this now-extinct endemic canid, and how the animal reached the island, 480 kilometres distant from the South American continent, remained a mystery. Possible hypothesis about the ancestry of this enigmatic canid suggested that the Falkland wolf was related to domestic dogs, North American coyotes, or South American foxes, and was brought on the islands by human colonists.

A new study, published in "Current Biology", compared the DNA sequence of preserved museum specimens with modern canids, and helped to solve some of the riddles of this animal.
The analysed DNA sequences show that the closest living relative is actually the maned wolf-, Chrysocyon brachyurus, an unusually long-legged, fox-like South American canid - from the physical appearance very different to the wolf. The researchers also found that the four Falklands wolf samples that they examined shared a common ancestor at least 70,000 years ago, which suggests that they arrived on the islands before the end of the last ice age and appearance of humans on the American continent. This fact seam's to rule out the prevailing theory that Native Americans brought the first animals on the Falkland's.
A possible remaining explanation for the wolves' presence on the islands, which have never been connected directly to the South American mainland, is the dispersal of individuals by ice or swimming logs.
During ice ages the sea level was up to 200m lower than today. Even if this is not enough to form connecting land bridges between the mainland and the islands, the resulting sea passages were much closer, maybe facilitating significantly the surviving of animals on their "travel" to uncolonized habitats.

Topography of the South American continet and bathygraphy, note the -200m area (data source)

Banana Flu pandemic: Vaccination now !!

2009-11-13T11:25:00.000-08:00

How Creationist 'Origin' Distorts Darwin
by Eugenie C. Scott, Ph.D.

Ray Comfort and I agree that "science is a wonderful discipline, to which we are deeply indebted." We agree that it would be nice for students to get a free copy of Darwins best-known book, On the Origin of Species. I'll even go further than he might: The Origin -like Shakespeare and the Bible- should be on every educated person's bookshelf. If you don't understand evolution, you can't be considered scientifically literate. And we agree that students should read the Origin thoroughly.

Unfortunately, it will be hard to thoroughly read the version that Comfort will be distributing on college campuses in November...

Creationism is coming to a campus near you, but don´t fear, a vaccine is here:
BANANA POWER NOW: Don't Diss Darwin.

2012

2009-11-11T12:28:00.001-08:00

NASA has put online a website to dismiss the predictions about the end of the world as we known it in December 2012. Doomsday scenarios comprise planets that hit earth, polar shift theory and as the last, but not least, the meteor of doom.

But when the (false) prophets claiming to know about the end had studied carefully the Mayan calendar, they would know that the end of the world will approximately be as following:

First, the very old goddess Chakchell, with her terryfing snake headdress, will shake out the waters from the jar of the gods.
Then, with the help of the dark god of the underworld, a owl is symbol of his power, they together will force the divine crocodile to spit out a even more deadly deluge of water. And finally even the holy hieroglyphs will cry and the world will sunk and drown.

Dresdner Codex, plate 47

That's what I claim is a good catastrophic Armageddon ... or as option watching another movie by R. Emmerich... (hurry up Chakchell !!).

Geo Art: An inconvenient truth about extinction

2009-11-10T12:46:00.000-08:00

It's seems that Geo-Art is spreading trough the Geoblogosphere. Here a short cartoon proving finally why the dinosaurs got extinct, and mammals get the victory gesture - seen in the legendary diary hold in the small inn in the Gubbio gorge (Umbria - Italy) with the infamous C/T iridium anomaly (the first entry in the book is by Alvarez itself):

No more ice on Kilimanjaro ?

2009-11-08T09:28:00.000-08:00

After Thompson et al. 2009, interview to Dr. Thompson mp3

The glacial record in Africa is restricted to the highest peaks of this continent, mainly to mountains of east Africa: Mount Kilimanjaro (5895m), Mount Kenya (5.199m), the Ruwenzori (5.119m) and on the northern margin of Africa in the High Atlas. Traces of two Pliocene-Pleistocene glaciations have been found on Mt Kilimanjaro, the oldest of which have been dated to about 2.0My (OSMASTON, 2004). Younger, in part uncertain glacier advances are dated to 1,0My, 0,4My and during the last glacial maximum (20.000y). Today three main glaciers persist on the summit of the volcano - the Northern Ice Field (NIF), the Southern Ice Field and the Furtwängler Glacier; some smaller glaciers are distributed on the slope of the mountain. Cores taken from all three glaciers showed that the ice cover on Kilimanjaro persisted for at least 11.700 years.

Isotopic record of oxygen isotopes from the Northern Ice Field (NIF), after THOMPSON et al. 2002

In modern times the dramatic loss of Kilimanjaro´s ice cover has attracted global attention, and has been a symbol for changing climate in Africa in popular media. The glaciers have considerable lost volume and surface, from 12,06 square kilometer in 1912 to 2,6-2,5 square kilometer in 2000. In the last 7 years ulterior 26% of this remaining ice are gone, leaving 1,85 square kilometer back. But not only the ice covered surface - easy to observe by aerial photographs - diminishes, but more important the glaciers are rapidly thinning, up to 0,5m thickness loss per year. This glacier mass lost is harder to determinate (mostly by measuring with stakes you got only punctual data) but crucial to understand the glacier balance.
If this melting rate persists, until 2022-2033 there will no more glacier ice left on the summit.

The widespread retreat of glaciers in Africa suggests a common driver, and not only local factors like deforestation, land use or humidity change on the slopes of Mount Kilimanjaro. The long record that this ice fields provided, demonstrate that for more then 11.000 years ice persisted without essential melting or mass lost, even during the end of the humid phase in Africa and change to more drier climate and subsequent droughts (p.e. 4.200 years ago). This seems to minimize the influence of changing precipitation on the glacier mass balance, and emphasizes changing in the temperature regime on the summit of the mountain.

References:

EHLERS, J. & GIBBARD, P.L. (2007): Glaciations. In (ed): ELIAS, S.A. (2006): Encyclopedia of Quaternary Science. Elsevier : 290-300

OSMASTON, H. (2004). Quaternary glaciations in the East African mountains. In J. Ehlers and P. L. Gibbard (eds): QuaternaryGlaciations - Extent and Chronology, Part III: South America, Asia, Africa, Australasia, Antarctica: 139-150.

THOMPSON, L.G. et al. (2009): Glacier loss on Kilimanjaro continues unabated. Proceedings of the National Academy of Sciences.

Worried about climate change?

2009-11-08T06:40:00.000-08:00

From the very big corporations that brought you "Turbo Capitalism" and in the last decades "Global Change" and "World Finance Crisis" comes the only - and 101% secure solution for the global crisis and catastrophes- no, not another CO2 producing climate conference in Helsinki - but SurvivaBall:

Continental drift

2009-11-07T06:19:00.000-08:00

Nov, 1880 - Nov, 1930

"The presence of those seeking the truth is infinitely to be preferred to those who think they´ve found it."
T. PRATCHETT (2003): Monstrous Regiment.

Illustration from Thomas Burnet´s book "The Sacred Theory of the Earth", published in 1684, where he tries to explain the shape of the earth by the biblical flood. Parts of the crust of earth broke up (first drawing), releasing water from the underground. This water covers the entire planet (second drawing), and finally flowing back in the fissures, leaves back a shattered crust that now forms islands and continents (last drawing).

Already after the first maps of the American continent were published (1507 and after) and become public, the similarity between the coast of Africa and America intrigued geographers and naturalists, and this fascination continued in the following centuries.
In 1620 the English philosopher Francis Bacon noted the jigsaw form in his "Novum Organum" and claimed that "it's more then a curiosity", and 38 years later the munch Francois Placet published "The break up of large and small world's, as being demonstrated that America was connected before the flood with the other parts of the world." He argued that the two continents were once connected by the lost continent of "Atlantis", and the sin flood beaked them apart.

The great naturalist Alexander von Humboldt explored South America from 1799 until 1804, and observed that the similarities between the two coastlines were not only restricted to the morphological pattern, but also geological features: mountain chains that seemed to end on the one continent, continued on the other , the Brazilian highland remembers the landscape of Congo, the Amazonian basin has it's counterpart in the lowlands of Guinea, and the mountain ranges of North America are - geologically - very similar to the old European mountains.
But still the flood argument was a strong one, and so he argued that the Ocean represents a large, ancient river bed, flooded by the biblical catastrophe. The French zoologist Jean-Baptiste Lamarck (1744-1829) developed a theory by itself, explaining the discovery of fossil marine animals on the dry land, he proposed that the continents "move" slowly, but irresistible, around the globe. The east coastlines of the single continents were eroded by the sea, but in the same rate new sediments were deposited on the west coast, so doing, the land were "flooded" many times by the oceans. Unfortunately, also for the lack of evidence for his theory, Lamarck was not capable to find a publisher for his "Hydrogéologie", and printed in 1802 on his own behalf 1025 copies, but only a small number of books could be sold.
The new century saw the birth a new therory to explain the shape of Earth, formulated by the American geologist James Dwigth Dana (1813-1895) - mountains and continets were products of the cooling, and shrinking earth.

After the theory of Dana, the modern continents represent remnants of the former earth crust, or the first parts of earth that solidified after the formation of the planet. The Austrian Geologist Eduard Sueß published in "Das Antlitz der Erde (1883-1909)" this hand coloured map, showing the primordial continents "cores", today separated by younger, during the contraction of Earth formed, and today water filled basins.

But this therory, explaining some aspects, couldn´t explain the irregular distribution of mountain ranges on erath, and why eras with strong tectonic movements alternate with "quiet" eras.

George Darwin, the son of Charles R. Darwin, explained the formations of the continents as result of the detachment of the moon from earth 57 million years ago. The American geologist Frank Taylor in contrary tried to prove that the moon was captured by earth some 100 million years ago, and the resulting tide waves rip apart the single continent on the planet.

Antonio Snider, an American scientist living in Paris, was the first in 1858 to publish a schematic representation of America and Africa forming a single continent. But he also explained the break up of the two landmasses by the strength of the great flood. Still no mechanism was known to explain if, and how, continents could move over the planet´s crust.

This 1858 drawing represents one of the first schematic maps to explain the drift of continents. In contrary to other naturalist, and later geologists, Antonio Snider-Pellegrini assumed a sudden, and very fast movement, caused presumably by the biblical flood.

Chicken Wing

2009-11-06T12:07:00.000-08:00

The 8th specimen of Archaopteryx was not found in the limestone formation of the Solnhofer Plattenkalke, in contrast to all other fossils, but in the overlying , and younger, Mörnsheimer Schichten in 1990. Only parts of the wings and skull are preserved. The exemplar is part of a private collection and still not studied, so the attribution to the genus Archaeopteryx is not proved.

Another fragmentary skeleton is the 9th fossil of Archaeopteryx, the specimen of the family Ottmann and Steil, or "Chicken wing", discovered 2004, and only preserved as the right wing missing parts of the digits. The proportions of the bones are very similar to the other fossil bones of the known Archaeopteryx specimens, also are the imprints of the feathers recognizable.

The dancer in the stone

2009-11-06T10:21:00.000-08:00

The 5th specimen of Archaeopteryx (syn. A. recurva; Jurapteryx recurva) is the smallest known, and is interpreted so to represent a juvenile animal. The fossil is well preserved, especially the skull. Discovered in 1951, it was first (as many times before and after) mistaken for a pterosaurian, and sold to the naturalist Franz Xaver Mayr, who also in a first moment determinated is as Compsognathus, a small dinosaur. After he realized his error, he halted the discovery secret until 1972, fearing legal problems for the non declared possession of such a special fossil. In 1972 he finally showed the fossil to the custodian of the natural collection in Munich, and in the following years Mayr and Peter Wellnhofer published the discovery. Since the opening of the Jura Museum in Eichstätt in 1976 the fossil is displayed in the collection of the Museum.

American Archaeoptery-X

2009-11-04T13:04:00.000-08:00

The Thermopolis-specimen, after the actual location in the Wyoming Dinosaur Centre, Thermopolis, is one of the best preserved fossils of Archaeopteryx, and the X-th in the order. The finding circumstances are unknown, in 2001 it was offered for sale, presumably by a private Swiss collector, first to the German museum of Senckenberg, but the costs were to expensive. It was so acquired by the Dinosaur Centre, finally described and presented in 2005 to the public. In this specimen the second toe is notable, like in the Deinonychosauria it could be stretched backwards.

The Sixth Bird

2009-11-03T12:48:00.000-08:00

The sixth specimen of Archaeopteryx was recognized during fossil-preparation work in 1987, and it is the largest known and considered an adult or subadult animal. Exact location and time of the discovery of the fossil are unknown, during the seventies it was treasured in the collection of the major of Solnhofen - Friedrich Müller.A worker of a quarry near Eichstätt claimed that it was discovered in 1985 and then sold illegal to the major. In 2003 the law case was closed, the provenance of the fossil - the investigated quarry - couldn't be confirmed. Today the Solnhofen specimen can be admired in the Major Müller-Museum in Solnhofen.

Old feather

2009-11-02T12:47:00.000-08:00

To celebrate the "Darwin year" on the Munich Mineral Show 2009 were displayed six of the known specimens of Archaeopteryx, and because it's a rare opportunity, and Archaeopteryx is a pop-icon of earth sciences, here some impressions:

The imprint of a single feather discovered in 1861 in a quarry near the village of Solnhofen. This fossil was the first evidence for birds in the lagerstätte of the Solnhofer limestone, and anyway the first evidence for Mesozoic birds. Studying this feather Hermann von Meyer proposed the species Archaeopteryx lithographica in 1861, even if today it is not clear if it can be related to the found skeletons in the same formation (this fossil is today hosted in the collection of the Paleontological Museum Munich, the counterpart is treasured in the collection of the museum for Natural history in Berlin).

To be continued...

The greatest show on earth

2009-09-29T12:56:00.000-07:00

No excuses more, because now you mustn´t even read: "The greatest show on earth: the Evidence for Evolution" by Dr. R. Dawkins as audiobook.

Picture by Darius Whiteplume's Tumblr.

The Permafrost Menace

2009-09-27T06:49:00.000-07:00

The term permafrost is primarily associated with regions such as Alaska and Siberia, with a vegetation-free tundra, rock-hard frozen ground, and with the famous finds of well preserved carcasses of ice age mammals. But permafrost occurs in much wider geographic range, at least 23% of the Earth surface is influenced by permafrost.

Permanently frozen ground or permafrost is by definition material (bedrock or loose material), which remains at least for one year or two winters frozen, with temperatures below 0 ° C. Water, and so ice, is not necessary "needed" in permafrost, therefore called dry permafrost, but this kind of frozen ground plays geomorphological a minor role.

Climatic change has important effects on the distribution and the energy balance of permafrost , so influencing the amount of ice conservated in it. Permafrost occurence depends of various climatic (like temperature, insolation, precipitation and snowcover) and also from geomorphological (like exposition) and biological (like vegetation cover) factors - the role and interplaying between this factors is still poorly understand.
Permafrost in the middle latutudes lays only some degress under the melting point of water of 0°C, even a sligthly warming of the mean air temperature - and surface temperature, can heavily affect permafrost. The distribution diminuishes, and the depth of the active layer - the layer of permafrost that defrost´s during summer, increases.

How exactly permafrost reacts to the observed warming of 0,5°C during the last century in the Alps is still poorly known, and the exact mechanisms not understand. The strong retreat of glaciers is obvious, but permafrost was though to react much slower, because of the insolation effect of the covering debris layer. But observations of temperature profiles in drillholes showed that percoliating water, resulting from melting of more superficial ice, can "tranport" heat much faster in the underground.

Studying permafrost is a hard job, especially if it hides inside compact rock. PermaNet drill site in the valley of Schnals.

Morains and talus cones not only are habitats for specific, sometimes endemic animals and plants, but consists of loose debris hold together most time only by ice in the cavities between the boulders. Loosing permafrost can destabilise rock walls and debris, causing rockfalls and debris flows, and so putting infrastructures and humans life in danger. In the last 10 years the greatest rockfalls in the Swiss Alps occured in permafrost affected areas, one of the most spectacular in summer 2006 felt from the east-wall of the Eiger.

The rockfall of the Thurwieser mountain (3.652m, 46° 29` 45`` N, 10° 31` 28`` E) occurred on 19.09.2004 (first image befor, second after). 4,5 million cubic meters material felt on the underlying glacier and boulders up to 50 cubic meters slipped on it until 2000m a.s.l. The rockfall was caused probable by ice degradation.

The melting permafrost can influence the percolation and the paths that groundwater can take, so influencing springs. Observations in the european Alps and the Colorado Front Range showed also a change in the water chemistry in lakes and springs where permafrost features, like rock glaciers, occur in the catchement area. The change in water balance and presence can also effect the distribution of vegetation and the species richness of a habitat.

Hochjochferner 1891

2009-09-26T12:59:00.001-07:00

The Hintereis -glacier (in the center of the picture), Hochjoch - glacier (left) and the Kesselwand - glacier, drawing by Schmetzer 1891. Position: 46°49`34``N, 10°50`20``E
"Aus den tiroler Alpen: Der Abschluß des Oetzthales mit dem Hochjochgletscher (links), dem Hintereisferner (in der Mitte) und dem Kesselwandferner (rechts oben). Nach der Natur grezeichnet von K. Schmetzer (1891)."

Accretionary Wedge #20: Why?

2009-09-24T12:58:00.000-07:00

Asked for the ultimate answer to the Ultimate Question of Life, the Universe, and Everything, Deep thought, the supercomputer created by the imagination of the science-writer Douglas Adams, asked the far more important question: What is the ultimate question itself?

An wise man once said, a fool can ask more then ten men of science can possibly answer, but a problem and a good question is the first step of scientific research.
Geologist and earth scientists in the past centuries where observing rocks, relationships between them, superposition, unconformities and many other features, and came to ask themselves the apparent simple question: how came this marine limestone on the top of the mountain, why the coasts of the continents resembles the conjunctions of a gigantic jigsaw, where all rocks deposited by volcanic eruptions or sedimented in a quiet ocean basin? Today a part of these questions seems trivial, but still some of them are not conclusively answered. And even if we assume a question is answered, changing also slightly the problem can open the ways to a bunch of new issues.

In a survey carried out on 753 scientist from different nations around the globe , the german magazine "Spiegel" asked for the greatest - still unresolved problems in geosciences, and not so surprisingly the results fit quite well with the ultimate questions that trouble the Geoblogosphere:

Lockwood asks directly from Outside The Interzone one of the most important question from a slightly different perspective, not why earth enabled the existence of life, but why life enabled the existence of earth? Without life, this planet wouldn't be "Earth." O r we can ask ourselves, would nonexistings men be concerned about nonexisting earth?

Today Humans were concerned about Earth, especially when geological phenomena threaten their lives and their property - like volcanoes. It seems today elusive, that once volcanoes and their products where considered by earth scientists only as local features, with no significance for the geological evolution of earth - living in quiet central Europe they underestimated the power of this fire mountains - or asked they simply the wrong questions?

Not so Tuff Cookie, introducing us in the burning question how Magma reaches the surface of Earth, and how to study it´s path without X-ray powers and invulnerability. To understand the mechanism of volcanic eruptions may helps to predict and mitigate the impact on our society - a very important question with even more important answers.

And Hypo-theses proposes the ultimate hypothesis: With ongoing research we realized that earth is a complex systems, with factors like the interior structure, the outer crust, the liquid and the frozen hydro- and atmosphere and the biosphere (and humans) interacting among themselves, so ... what would be, if we really understand earth?

Many thanks to all participants for the content and the questions of this edition of the Accretionary Wedge. But don´t panic - at least one important question can be answered now - who is hosting the next Accretionary Wedge?

Lac du Bouchet

2009-09-12T09:27:00.000-07:00

How Florian correctly answered, the WoGE was the maar lake of Bouchet and it´s very long stratigraphic sequence.

Located in the south eastern part of the French Massif Central, the volcanic region of Velay contains numerous maar craters. Pollen analysis has been carried out on lake sediment sequences obtained from three of these craters - Lac du Bouchet, Ribains and Praclaux. The presence of thick trachytic tephra layer has enabled correlations between the sequences. This has led to the reconstruction of a long continental sequence from 450ka ago to the present.

The attribution of the sequence to the last five climatic cycles is based on an apparently continuous succession of warm and cold phases, which correlates with the marine oxygen isotopic record. Tephra layers in the organic deposits of Lac du Bouchet provided Ar40/Ar39 dates with an average of 275ka - after this considerations the Lac du Bouchet temperate phase is correlated to the Marine Isotopic Stadium 7.

Lac du Bouchet (44°55´N, 3°47`E, 1.200m altitude) is a 28m deep lake, and has been the subject of numerous geological and biological studies. It yielded a sediment sequence extending from about 325ka to the present.

The Bouchet sequence can be subdivided by the amount of pollen taxa in three interstadials, which shows a classical succession of tree species, from cold tolerant at the beginning, to warm climate species, to again cold tolerant trees.

The proposed chronostratigraphy for the Velay maar sites (after REILLE et al. 2000, modified).

The Bouchet I interstadial is characterised by the presence of great quantities of Carpinus pollen, other thermophile taxa like Abies and Fagus are rare, or like Taxus complete missing. The Carpinus forest was probably the dominant vegetation everywhere in Velay at that time.
The Carpinus forest was then replaced directly by a Pinus forest, the latter marking the end of the interstadial and maybe a sudden cooling.
The Bouchet II interstadial shows similarities with the fist: again a Carpinus forest develops, but this time other trees like Ulmus, Corylus, Abies, Fagus and Picea must be also been present with significant numbers. As usual, the intestadial ends with a Pinus forest.
The third interstadial - Bouchet III, differs in significant taxa appearance and significance from the earlier two interstadials. Alnus viridis, today absent in the Massif Central region, but found as pioneer species in the timberline of the Alps, plays a mayor role in the first phase of the interstadial. This tree is then replaced by Ulmus, Quercus and Corylus, an Oak forest occasionally coexisting with a Picea forest develops. Carpinus this time doesn't form a forest of its own.

The establishment of tree taxa depends not only by the climatic conditions, but also from the distance of an investigated site from the glacial refugia of the species, and the capability of this species to spread. This maybe can explain the differences between the forest developments in the three interstadials.

The site of the ancient (with sediments filled) maar of Praclaux, in the vicinity of the Lac du Bouchet, today a quiet pasture.

References:

REILLE, M.; BEAULIEU DE J.L.; SVOBODA, H.; ANDRIEU-PONEL, V. & GOEURY, C. (2000): Pollen analytical biostratigraphy of the last five climatic cycles from a long continental sequence from the Velay region (Massif Central, France). Journal of Quaternary Science (7): 665-685

Where on Google Earth #173

2009-09-08T12:47:00.000-07:00

The last excursion of WoGE (pronounced WvoGoEe) showed us some important type localities - locations where for the first time a mineral was found and described, or where it is found in accessible and well recognizable specimens - so the last round for example was the mineral "Tyrolensis" - no wait, was it "Saussurite", or should we name it "Arduinoite" ?

No - even if a first chemical observations of a strange Mg-rich limestone was published in 1779 by the Italian geologist Giovanni Arduino, the honour to became named a mineral in 1792, and then a mountain range after him, pertains to a restless "voyageur".
With 26 years - after some troubles with justice- he decided to travel and visited different geological localities of the European continent (a early Woge-Player?), so in 1784 he came to the Italian province of Calabria, after the great earthquake. And being there, he visited another well known geological phenomenon of the region on the great island nearby - even when then you couldn't go skiing on the top of this geological feature.

Remaining at home in his country he could also have visited Mg-bearing black rocks (this time not related to his name) and so the geological feature that he discovered active in Italy - even when these features today are filled with a complete opposite element to the strange things in Italy. And there finally it is , the WoGE 173, with 500m in diameter:

But that's good so, because if something fells in this hole, it remains there, and when after 325ka climatologist cam to drill, they sometimes discover another warm "climate" - and name it after the locality they found it - so at end, it's just another type locality.

I think from the first clues you can quickly deduce what country ´s geology you have to study to find the geological "spot" - it would be sufficient to name the general context of this point, maybe the specific content of the "holes" is known better to quaternary geologist - but if you really good (and I expect nothing lesser) you can also explain why the keyword here is "climate".

"For any new players to Where on (Google) Earth, simply post a comment with latitude and longitude (or a description of the location) and write something about what the features in the picture are, or how they have developed. Also you need to explain how the keyword fits in there. If you win, you get to host the next one - with the new twist to the game: the location should be connected to the previous one by some common concept, or “keyword”."

Schott's Rule could be applied: former winners have to wait 1 hour for each WoGE they got right.

Good luck !

debris flow calendar

2009-09-07T12:37:00.000-07:00

The past weekend strong rainfalls caused various debris flows in my near surrounding area, with significant damages and one roadmen missing after a debris flow hit the street he was clearing from detritus.

To understand where and when these events hit is vital for appropriate response tactics and risk evaluation for urban areas. Thereby, the frequency and magnitude of debris flow events are of especial interest, also in view of climate change and human impact.
Information for past debris flow events in historic time can be obtained by studying archives or contemporaneous eyewitness reports/images. Prehistoric events can be reconstructed by 14C-dating of buried soils, dendrochronolgy or lichenometry. The disadvantage of these approaches is their limited time span and coarse resolution.

In the bottom sediments of the lake of Braies, in the Dolomite Alps, another possible long term record was, and still is, studied (IRMLER 2003; IRMLER et al. 2006). The lake Braies is an alpine lake on 1.492m a.s.l. with a maximum area of nearly 36ha and a catchment area of 30 square kilometres. It is surrounded by mountains up to 2.800m, dominated by dolo- and limestone formations. Several debris flow cones extend from the slopes of the mountains to the southern and eastern shores of lake Braies.

View to south with the main debris flow cones entering the lake Braies.

Simplified geological map of the lake and surrounding area (after IRMLER 2003).

In thin sections recovered from cores taken from the bottom lake sediments between annual laminations several "event layers", representing debris flows, were recognised.
Entering the lake, the debris flow brought more fine sediments in the lake then the average sedimentation rate of some millimetres per year. Under the microscope graduated layers, with progressive fining upward sequence, from well-sorted fine to middle sand at the base to silt and clay on the top could be recognized. Load casts and flame like structures support reconstructed rapid deposition. These structures indicate that the sediment moved as underflow (hyperpycnal flow - density current) into the lake basin.
A second category of layers lacked the above mentionetd characteristics, nevertheless these layers show a graduation and are much thicker than the surrounding lamination - up to seven times. These sediments are interpreted as deposits of overflow currents (hypopycnal or homopycnal flow).

Example of the studied core with recognizable annual lamination (from IRMLER 2003).

Erosive contact between annual lamination and a debris flow layer. The base of a debris flow layer is usually very coarse and the single grains more or less the same size.
Photo C) and D) shows so-called "flame structures" and small grooves - caused by the erosion of a debris flow event (Picture size ca 3.9 mm), from IRMLER 2003.

With this approach a debris flow calendar for the last 2250 years could be reconstructed. (IRMLER et al. 2006). During this time the recurrence interval of debris flows varies between 1 and 127 years. At an average of every 16 years a debris flow was deposited. The comparison with climatic phases, from the "Medieval Warm Period" to the "Little Ice Age" showed no significant correlation of events in the catchment area of lake Braies with climatic phases.
The study shows that lake sediments represent a good archive for reconstructing debris flows. In doing so, the record provides the possibility of estimation from the past the threat posed by natural hazards and gives important data for future hazard prediction assessment.

References:

IRMLER, R.; DAUT, G. & MÄUSBACHER, R. (2006): A debris flow calendar derived from sediments of lake Lago di Braies (N. Italy). Geomorphology 77:69-78
IRMLER (2003): Seesedimente als natürliches Archiv zur Erstellung eines Murkalenders am Beispiel des Pragser Wildsees (Norditalien). Ph.D. Thesis, University of Jena, Germany.

Glacier Erosion

2009-09-05T12:52:00.000-07:00

Forms of glacial erosion represent some of the most widely distributed and recognizable indicators for past glacier extent. The discovery that polished rock surfaces were formed trough glacier abrasion, and the subsequent mapping of this feature on valley floors very distant from recent glaciers, was vital for the support of the "glacial theory" in the mid-1800s by the geological community.

The glacial striations of Le Landeron on Lake Biel, visited by the participants of the excursion of the Société Géologique in 1838, in a representation of Agassiz's work Etudes sur les glaciers of 1840.

Abrasion is the process of (frictional) wear, produced by surface rubbing against each other, and is achieved in the subglacial environment by sliding of debris-charged ice across the rock-bed.
Roches moutonées are the classical example of subglacial bedrock erosion, with abrasion dominating on the upstream (stoss) side and plucking (material pull off) on the lee side. This results in a highly unsymmetrical form, with a plain, upward side and a step to vertical termination.

To be continued...

Geologists Who Say "Nye"

2009-09-04T12:13:00.000-07:00

Roches moutonnées of the last glacial maximum seen by the "Geotope Fischbach" (Bavaria) with Nye channels (after a British physicist) - subglacial channels eroded by meltwater under high pressure in the limestone formation of the "Wettersteinkalk".

In warm-based glaciers, also called temperate glaciers - with the bottom near or slightly above the freezing temperature, water flows in or on the bottom of the glacier forming subglacial streams in channels, that finally join at the snout, forming a glacier outlet.

There are three types of subglacial channels, depending on such factors like glacier movement, bedrock topography and lithology:

N-channel or Nye-channel: incised in the underlying bedrock.

R-channel or Röthlisberger-channel: incised in the ice (and so not found in "fossil" form).

C-channel or Clarke-channel: partly incised in the bedrock and ice, a combination of the formerly mentioned types.

#19 AW & call for #20

2009-08-31T11:53:00.000-07:00

The #19 Accretionary Wedge is up on Dino Jim´s Musing, and this time it will stimulate all your senses...

The next Accretionary Wedge will be hosted here - let's say because it's the #20 on 20.09.2009 (easy to remember), and after explaining how somebody becomes geologist, or how to teach geology, and why "bad" movies and cake are so important in geology - why not asking:

What remains to be discovered for future earth scientists what we (still) don't know about earth? What are the geological riddles that still lack answer - all questions are allowed - it could be a local anomaly, or a global phenomena, or something strange...(Naturally you can also include a possible answer to your problem).

And when you are not afraid to pass this edition of AW, we are still searching host's for the next edition in October.

Submit your question simply by posting a link as comment here or by mail.

Quaternary stratigraphy

2009-08-29T09:34:00.000-07:00

The quaternary has a long-established tradition of sediment sequences divided on the basis of climatic changes influencing the deposited sediments, particularly sequences in central Europe and North America where divided with this approach.

The German pioneers PENCK & BRÜCKNER divided on the basis of glacial diamicton and nonglacial deposits the terrestrial stratigraphical sequence in the Alps into four main glacial (glaciation), and corresponding interglacial periods. This scheme was based on the identification of glaciofluvial sediments - attributed to glacials- that could be traced upstream until corresponding moraines. The fossil soils between these deposits were interpreted as interglacial weathering.
Although later workers added earlier events to this first sequence, the basic structure remained dominant for more than half a century - and seemed to be recognised all over the world.

In North- and Central Germany the relative division of the Quaternary is based - following the tradition- mainly on glaciofluvial gravels, fossil soils, Loess, moraines and limnic sediments.
The extensive mining for coal and gravel provided exceptionally vast outcrops to study these sediments.

Map with the discussed localities and the main recognized ice sheet stands.
See also: Gamsenberg / Westeregeln / Hundisburg / Bilzingsleben / Ehringsdorf /Weimar and Pennickental

The gravel pit of "Wallendorf" in Thuringia exposes typical, 12 to 5m thick gravel deposits - denominated "Wallendorfer Schotter". These gravels, with rocks outcropping in the Thuringian basin and Thuringian forest, were transported to this locality by the small rivers Ilm and Unstrut, that joined the greater Saale river.

Gravel pit with the "Wallendorfer gravel", attributed to the Holstein interglacial (ca. 350-300kyr).

The Wallendorfer gravels overlay with an unconformity a moraine (Elster) and varved sediments, and are overlay by remains of a younger moraine (Saale), so the unit was attributed to the "Hauptterassenkomplex", the sequence of fluvial terraces deposited during the classical Holstein - interglacial.
The decalcification of the lower part of the partly calcareous gravels, and also the studied mollusc assemblage, seems to confirm a temperate climate with ongoing weathering and soil development.
But the presence of lithic artefacts and bones of ice age steppe animals, like mammoth, auerochs and reindeer, also with ice wedge casts, demonstrates that the upper part of the gravels were already deposited during cold conditions and the beginning of a glacial.

Ice wedge cast in the upper sequence of the "Wallendorfer gravel". This features are typical for periglacial conditions.

Varved sediments and the moraine of the Elster glacial - the next "deeper" sediments in the stratigraphic column- can be observed in the gravel pit "Rehbach".

Gravel pit "Rehbach".

Here, in a proglacial lake, fine clayey sediments were deposited until the advancing ice sheet run down the previously deposited sediments. On the basis of the moraine reworked, probably transported in frozen state, clasts can be observed.

Varved lake clay -deposited in a proglacial lake.

The contact between the varved lake sediments (note the brown layers) and the massive, loamy moraine.

Sandy clast with some pebbles in the transition area between lake sediments and moraine, probably reworked and fluvial transported (in frozen state) material then incorporated at the basis of the moraine.

What seems like an easy recognisable alternation of glacial and interglacial sediments, can however present local conditions that can be very tricky. In the gravel pit Karsdorf a succession of polymict gravels is suddenly overlay by sand with gravel lenses. This seems inconsistent with any sudden climatic change, or stratigraphic pattern in the region.

Outcrop in the gravel pit "Karsdorf", sand is overlay by large scale lenses of pebbles and coarse grained rubble.

Shear imbrication typical for debris flows overlay sandy sediments of fluvial orogin.

Only the study of the large outcrop, the topography and the underlying geology solved this apparent mystery.
The upper sand-gravel-rubble unit represents an alluvial fan, that coming from the circumjacent limestone hills joined the former pathway of the Unstrut river, and probably forced the river to change flow direction.

The discussed division is fundamentally lithological. However sediments are not unambiguous indicators of climate (for example the "Wallendorf gravels extend from a "warm" climate to a "cold"), so that other evidence, such as fossil assemblages, characteristic sedimentary structures (including periglacial structures) or textures, and soil development must be also considered. Local and regional variability of climate complicates additionally the attribution of sediments to climatic phases. The correlation between stratigraphy of different localities is mostly only possible were large outcrops are present, or very distinct sediments were found.

The climatic subdivision of the Quaternary is not without problems, in contrast with the rest of the geological column, which is divided using time (chronostratigraphy). The relative correlation between terrestrial glacial and interglacial periods is difficult and restricted mostly geographically - especially the correlation with the well dated and accepted marine records, that at least shows 40 climatic oscillations during the Pleistocene, is still at the first steps.

References:

GIBBARD, P.L. (2006): Climatostratigraphy. In (ed): ELIAS, S.A.: Encyclopedia of quaternary science. Elsevier : 2819-2847
BERNHARDT, W.; THUM, J.; SCHNEEMILCH, M. & RUDOLPH, A. (1997): Flußschotter als Schaufenster in die Zeit der ältesten Besiedelung Mitteldeutschlands. Archäologie in sachsen-Anhalt Nr.6. Archäologische Gesellschaft in Sachsen-Anhalt, Halle
WEBER, T. (1996): Das Paläolithikum und das Mesolithikum in Mitteldeutschland. Archäologie in sachsen-Anhalt Nr.6. Archäologische Gesellschaft in Sachsen-Anhalt, Halle

Caves and the dream of long term records

2009-08-28T12:19:00.000-07:00

Within the Alps, long term climate records, ranging to the last or even to the penultimate interglacial are exceptionally rare. We are simply lacking sediments of these periods - sediments of interglacial's were systematically eroded by the (re)advance of glaciers, lay hidden under younger sediments (mostly postglacial alluvional river deposits) or are simply not yet recognised.

In cave systems we are not (so) affected by the destructive power of glaciers, so there maybe can be found sediments ranging much deeper in time, with a record much completer then in the outside world.

Speleothem growth depends strongly from temperature and water chemistry, and water in liquid form depends strongly by temperature of the environment outside the cave. During a cold period, water will be trapped in form of ice on the surface, and water percolation in the underground will be very restricted or completely missing - the speleothem will stop to growth. During warming, and melting of ice, again water is available, and the speleothem goes on growing. So just the presence of speleothems can provide a first clue to reconstruct past climates. But even better - the isotopic composition of the precipitation changes with the amount of water trapped in ice shields - so measuring the relationship between the two oxygen isotopes (the "light" 16O and the "heavy" 18O) in the- from the water deposited - carbonates, can give a direct information's of extend of ice shields, and so climate, during the past. And the carbon isotopes 13C and 12C, also found in the carbonate, give hinds on vegetation and soil cover of the catchment area of the cave. Plants assimilate preferred the lighter isotope - a high values of delta13C indicate low or even negligible input of soil-derived organic carbon into the dripwater.

Spannagel cave is a large high altitude (entrance to the cave 2.531m, extending down in two main branches to ca. 2.200m a.s.l.) cave network with approximately 10km of length in the Zillertal Alps of Austria.

The "Hintertux glacier" with the morain of the last highstand (1850). The entrance of the Spannagel caves - and also the Spannagel hut- lies on the upper end of the left morain.

It is the largest out of a series of more than 30 caves that developed within the Jurassic marble that covers the "Zentralgneiss" - the tectonic uplifted gneiss core of the "Tauern window", and is itself overlie by the phengitic gneisses.

The area above the cave today is ice free, but it was covered partially by the Hintertux glacier until 1850, and covered entirely by up to 250 thick ice during the past glacial. U/Th dates in the cave showed that deposition of the speleothems occurred repeatedly during the past few hundred thousand years, and is still ongoing, thanks of the constant temperature (1-2°C) in the cave slightly over the freezing point of water.

A stalagmite in the cave, composed of dense, columnar calcite, apparently grew without significant interruption for ca. 50 ka, albeit at a very slow rate, during the penultimate interglacial. The oxygen isotope record shows three prominent maxima, representing three warm phases, separated by a long earlier and a shorter later cold period. The mid points of the transitions into the three warm phases occurred at 240 ± 3 (correlated subsequently with the MarineIsotopicStadium 7.5), 215 ± 2 (MIS 7.3) and 200 ± 3 ka (MIS 7.1) and the end of the interglacial (MIS 7/6 transition) was dated to 190 ± 3 ka.

During full glacial periods no speleothem growth could be found. During the transition of interglacial to glacial conditions the sudden drop of the isotopes values suggest a cooling, but speleothems growth continues. Comparing the curve of the oxygen isotopes with the carbon isotopes shows a remarkable pattern - both curves appear very similar, relatively high delta18O values indicating warm atmospheric conditions coincide with high delta13C values. This suggests very little if any vegetation at this cave during the warm periods, and so less favourable conditions than today - were at least a thin soil developed.
The later interglacial (MIS 5), and also the Holocene show data with higher values of delta18O, and a low delta13C value during the "high stand" of oxygen - high temperature and thick soil and vegetation cover.

Continuous stable isotope record of speleothem growth during the Marine Isotope Stage 7 at the high-alpine Spannagel Cave, Central Alps. SPÖTL et al. (2008): Spannagel Cave, Austria MIS 7 Speleothem Stable Isotope Data. Age is given in kyr BP, isotope ratio per mil VPDB).
Relatively high (reaching -8 to -9 0/00) delta18O values indicating warm atmospheric conditions, these values during the observed interglacial coincide with relative high delta13C values (>2 0/00). The 13C isotope derives mostly of anorganic sources (p.e. dissolving limestone), so high values are sign of lacking vegetation or organic rich soil cover. During "cold periods" complete lack of soil and vegetation produces the high peak between 230-220kyrs.

These facts let conclude that the penultimate interglacial posess three major climatic phases, with warmer periods separated by cooler periods. On average this interglacial was less warmer then the last interglacial or the Holocene in this altitude, with consequent lower equilibrium lines for glaciers. The catchment area of the Spannagel cave must be covered by ice, but the ongoing growths of speleothems demonstrate the presence of water - this implies warm based conditions beneath the ice. Only during full glacial conditions no speleothem deposit occurred.

References:

SPÖTL, C.; MANGINI, A.; BURNS, S.J., FRANK, N. & PAVUZA, R. (2002): Speleothems from the high-alpine Spannagel cave, Zillertal Alps (Austria). In (ed.) SASOWSKY & MYLROIE: Studies of Cave Sediments: Physical and Chemical Records of Paleoclimate
SPÖTL et al.(2006): The last and the Penultimate Interglacial as Recorded by Speleothems From a Climatically Sensitive High-Elevation Cave Site in the Alps. In SIROCKO, F. et al. (ed): The climate of past interglacial. Developments in Quaternary Science 7.
VOLLWEILER, N.; MANGINI, A.; SPÖTL, C.; SCHOLZ, D. & MÜHLINGHAUS, C. (2009: Stalagmites from Spannagel cave (Austria) and holocene climate. Geophysical Research Abstracts. Vol.11

Mountains as only witnesses

2009-08-22T07:53:00.000-07:00

Like islands in the sea small hills, only some dozen meters in height, rises from the flat landscape of the "Orla-valley" south of Weimar. These “mountains” consists of limestone of ancient reefs, growing once in the Permian "Zechstein - sea". Tectonic and erosion have done they dirty work since them, leaving behind only isolated “Zeugenberge” (rude translated in Witnesses mountains) from the marine deposits.

The archeological site "Gamsenberg".

In a flat landscape every vantage point, that enables a hunter to overlook a vast territory, is of strategic importance. And in fact during the last ice age early man observed from this Zeugenberge the glacial steppe in search for the big herds of mammals.

Today the summits of these hills are mostly flat, covered by dense shrubby vegetation, and the surrounding landscape is characterized by villages, fields and scattered trees.
During excavations in a depression on the summit of the “Gamsenberg” – presumably in a karst depression or a collapsed cave - underlying 1,5m thick Loess deposits from the last glacial, a fossil soil was discovered, that contained lithic artefacts, bone fragments and charcoal. This paleosoil developed under warm climatic conditions on rubble of the underlying limestone, this rubble also shows cryoturbation.

The stratigraphic section of the archeological site "Gamsenberg". The upper part consists of Loess deposits, that overlay periglacial displaced rubble and rock fragments (cryoturbation).

Dating of glacial loess samples resulted in ages between 44.700+-4.500 and 41.900+-4.600 years. Between this stratigraphic layer and the horizon with the artefacts bones of micro mammals were found, especially the remains of pika (Ochotona) and lemming (Lemmini) indicate dry, cold conditions. Dating of the layer with the artefacts gave an age of 52.500 to 70.900 years, the bone fragments in this layer belong to animals like elk (Alces), horse (Equus hydruntinus and taubachensis), stag (Cervus elaphus), deer (Capreolus capreolus), auerochs (Bos) or bison (Bison) and a undetermined proboscidean (Mammuthus ?).
This animal assemblage is indicative for a dry, continental to boreal climate, with a mosaic of tree spots and steppe areas. The paleobotanic remains are also indicative to a climate with warm summers, but an annual average temperature to low to permit the establishment of deciduous tree forests.

The only time period that coincide with the radiometric ages, and also with a change between warm to cold climate temperatures, like indicated by the sedimentological and paleontological evidences, is the Odderade interstadial between 70 to 60kyrs during the Weichsel ice age.

Humans, presumably Neanderthals, used the Zeugenberge as ideal vantage point to overlook the steppe with sparse wood spots during an interstadial of the last glacial period. Here they prepared their tools, using rocks like flintstone (found in morainic deposits 20 kilometres away), quartz, greywacke and siliceous schist. After spotting a herd of animals, and (hopefully) successful hunt, they returned and butchered their prey on this site. Then, during full glacial conditions some 50.000 years ago wind transported dust covered the abandoned site, and only today, the karst fissures return their hidden secrets.

References:

WEBER, T. (1996): Das Paläolithikum und das Mesolithikum in Mitteldeutschland. Archäologie in sachsen-Anhalt Nr.6. Archäologische Gesellschaft in Sachsen-Anhalt, Halle

Dating cave sediments

2009-08-21T13:18:00.000-07:00

The decay chains between radioactive and a series of daughter isotopes is a useful tool to date sediments and rocks.

The radioactive decay process of uranium (238U and 235U) and thorium (in the form of either 230Th or 232Th) were investigated in 1938, but only in the 1950s and 1960s the method was applied to date lacustrine carbonates, marine sediments, corals and cave calcite deposits.

Thorium is a daughter product in the 238U decay chain. This element is much less soluble in water than uranium and is not found in groundwater, thus, speleothems (including flowstones, stalagmites and stalactites) formed in caves as a result of precipitation of calcium carbonate from aqueous solutions, will show an uranium-, but no thorium content. Thorium will be produced only as the uranium isotopes decay with time, providing a dating tool for such materials in the age range for some 100ka.

Speleothems are well suited for this dating method because their calcite crystals are usually large and have little tendency to recrystallize after deposition, forming so a "closed" system, where no contamination can "enter", and no information can "escape".
When viewed in cross section many speleothems display a prominent laminated structure (growth layers), caused by variation of the deposition conditions and so the deposited material (p.e. amount of fluid inclusions or organic matter).

The growth of speleothems depends not only from the presence of water, but also of it’s content of dissolved CO2. Before percolating through the bedrock, surface water is exposed first to atmospheric CO2 and then to soil gases enriched in biogenic CO2, from where most dissolved CO2 in groundwater comes.

The stratigraphy of the Conturines cave was recorded during the excavations conducted from 1988 to 1990, from 1996 to 1998 and in 2001. As excavation site the first encountered area with the scattered bones and skulls, where the small conduit opens in the much larger main hall of the cave – denominated conveniently “hall of skulls”- was chosen. The floor of the upper parts of the cave is covered by up to 2m thick flowstone that shows a fine lamination, maybe representing annual cycles.

It is overlain in turn by sand, fossiliferous dolomitic sand, again sand without fossil and finally large blocks.
The presence of such thick flowstone implies, that there were abundant precipitation and conditions favourable to develop soil horizons and vegetation cover in the catchment area of the cave. This limits the period of flowstone genesis to an interglacial or a warm interstadial period.
The fossils of cave bear are found only in the sand overlying the flowstones, implying that this deposit is younger. Cave bears were herbiverous animals, but today vegetation can found only 1.000m lower. During the occupation of the cave by the cave bear, vegetation was aviable in immediate vicinity, this also let´s assume that this deposits represents another warm period, with a shrub- and treebelt extending much higher then today.

So at least we need two periods were the temperatures reached higher values then today on this site – this was the case during the interglacials of the Eemian (130 to 120kyr) and the Holstein (350-300kyr). The comparation of the anatomical features of the Conturines bear with other high alpine extinct bear species seemed to confirm an minimal age between 65.000 to 30.000 years, implying a hypotetical warm and icefree period just before the glacial maximum 20.000 years ago.

So it is possible by the stratigraphy and the evolution “niveau” of the bear fossils to restrict the sedimentation phase in the cave to a period between 300kyr and 30.000 years ago.

It’s notable that the radiometric dating method confirmed in part this hypothesis. The dates of the flowstone samples resulted beyond the range of dating of 350kyr by the thorium - uranium method. The bone-bearing sands are much younger, the two oldest dates obtained by dating the bones are 87+-5kyr and 108+-8/-7kyr. Similar to the flowstone dates, the C14 method applied to the bones resulted in an age older then 39.000 years - beyond the limit of this method.
Even if this shifts the possible ages for the first sedimentation phase considerably to older ones, the flowstone still could be deposited during, or slightly before the Holstein, or – and this would be very exceptional, during the Cromer interglacial (800kyr).
Then a sedimentation phase follows, with the deposition of grey, yellow and red sand, containing no fossils, overlaid by the fossil bearing sand and rubble layer. The radiometric results seems to confirm an age for the occupation of the cave by the bear during, or just after the Eemian.
Then erosion removes and reworks in part the fossiliferous sandy layers – channels forms, which later were refilled with an grey sandy material, again lacking fossils.

This example shows how the limitations of the different dating methods can be compensated in part by careful observations and the “strengths” of other methods, and many different results are needed to reconstruct the sedimentation history in a "restricted" environments like caves.

References:

SCHWARCZ, H. Speleothems. In (ed): ELIAS, S.A. (2006): Encyclopedia of quaternary science. Elsevier : 290-300
SPÖTL et al.(2006): The last and the Penultimate Interglacial as Recorded by Speleothems From a Climatically Sensitive High-Elevation Cave Site in the Alps. In SIROCKO, F. et al. (ed): The climate of past interglacial. Developments in Quaternary Science 7.