Dienstag, 8. Dezember 2009

The Future Of Mankind

Carl Sagan Reflects:


Freitag, 4. Dezember 2009

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

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?

Montag, 30. November 2009

Dating catastrophes

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Historical references are the most reliable sources for reconstructing the temporal distribution of catastrophes, especially for the last few centuries.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

Sonntag, 29. November 2009

An Animal Fable from the Upper Cretaceous

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."

Samstag, 28. November 2009

Mission 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.

Dienstag, 24. November 2009

Sonntag, 22. November 2009

Darwin's rat and other strange mammals

"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, whe
re 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 relati
on 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

Freitag, 20. November 2009

Extinctions & Excrements

"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 c
omparable 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 la
ndscape 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----------

Dienstag, 17. November 2009

Cool Artiodactyls

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.

Sonntag, 15. November 2009

The mystery of Darwin's wolf

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 Falkla
nds 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)

Freitag, 13. November 2009

Banana Flu pandemic: Vaccination now !!


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.

Mittwoch, 11. November 2009

2012

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.


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

Dienstag, 10. November 2009

Geo Art: An inconvenient truth about extinction

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):

Sonntag, 8. November 2009

No more ice on Kilimanjaro ?

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.

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Samstag, 7. November 2009

Continental drift

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 E
nglish 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 "quie
t" 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.

Freitag, 6. November 2009

Chicken Wing



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


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.

Mittwoch, 4. November 2009

American Archaeoptery-X

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.

Dienstag, 3. November 2009

The Sixth Bird


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.

Montag, 2. November 2009

Old feather


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...

Dienstag, 29. September 2009

The greatest show on earth

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.

Sonntag, 27. September 2009

The Permafrost Menace

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.

Samstag, 26. September 2009

Hochjochferner 1891


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)."

Donnerstag, 24. September 2009

Accretionary Wedge #20: Why?

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, relatio
nships 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 glo
be , 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." Or 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?

Samstag, 12. September 2009

Lac du Bouchet

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

Dienstag, 8. September 2009

Where on Google Earth #173

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 !

Montag, 7. September 2009

debris flow calendar

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.