Field of Science

30, June 1908 : The Tunguska Event

"It was nothing of this earth, but a piece of the great outside; and as such dowered with outside properties and obedient to outside laws."
"The Colour Out of Space", by H.P. Lovecraft (1927)

In the morning of June, 30 1908 eyewitnesses reported a large fireball crossing the sky above the region of the Stony Tunguska (PodkamennayaTunguska) in Siberia. A series of thunder was heard to the village of Achajewskoje - in a distance of 1.200 kilometres.
At the same day at various meteorological stations of Europe seismic and pressure waves were recorded, and in the following days strange atmospheric phenomena were observed, silvery glowing clouds, colourful sunsets and luminescence in the night.

Local newspapers in Russia reported about a meteorite impact based on the eyewitness reports, international newspapers speculated about a possible volcanic explosion - the events after the eruption of Krakatoa in 1883 were still vivid in memories.
Dr. Arkady Voznesensky (1864-1936), Director of the Magnetographic and Meteorological Observatory at Irkutsk from 1895 to 1917, collected the eyewitness records and proposed as first the hypothesis of an extraterrestrial impact, however the inaccessibility of the area and the political situation in Russia prevented further research.
Only 13 years later the Russian mineralogist Leonid Alexejewitsch Kulik, reading some of the eyewitnesses' accounts about an explosion and large glowing object above the Taiga, became interested in the phenomena - there was also the hope to recover precious extraterrestrial metals from the supposed meteorite.
Kulik first had to travel to the city of Kansk, where he researched ulterior accounts or reports in the local archives. Most of the recuperated stories refer to large fireballs, flames and up to 14 subsequent thunders. In March 1927 he arrived at the outpost of Wanawara and then on 13, April Kulik discovered a large area of 2.150 square kilometres where all the trees were torn apart, lying on the ground.

Fig.1. The forest of Tunguska completely leveled by the shock wave of the explosion, photograph taken by Evgeny Krinov in 1929.

Despite his intensive survey, he didn't locate a single great impact crater as expected, but he found some circular pits that he interpreted as impact craters; however no meteoritic material was discovered in the entire area.
In autumn 1927 a preliminary report by Kulik was published in various national and international newspapers, the destroyed forest and the event that he described became later known as "Tunguska Event".
Kulik formulated one of the first hypotheses to explain the phenomena and the lack of evidence on the ground, he proposed that a bolid exploded already in the atmosphere, causing the explosion and devastation, single minor fragments became buried in the swampy ground, which was soft enough to collapse above them and didn't preserve the typical morphology of an impact crater.
In 1929 Kulik returned to the supposed impact area for three times, excavating and drilling into the swamp, hoping to discover some fragments of the bolid, however unsuccessful.
Kulik will die in 1942 in German imprisonment.


In 1934 Sowjet scientists proposed a new comet-hypothesis trying to explain the apparent lack of extraterrestrial material: a comet composed principally of ice entered the atmosphere, exploded and vaporized completely.

The lack of direct evidence generated many speculations and hypothesis:


Between 1945 and 1959 the engineer Aleksander Kasantsews formulated, based on the impression left by the first atomic bombs, an unusual explanation involving a nuclear explosion of possible extraterrestrial origin.
In 1973 American physicists published in the journal Nature the idea that a small black hole collided with earth, causing some sort of matter-antimatter explosion.
The German astrophysician Wolfgang Kundt and subsequent Jason Phipps Morgan of the Cornell University in Ithaca and Paola Vannucchi from the University of Florence proposed in the last years an ulterior hypothesis: "Verneshots", in reference to the author of the novel "A Journey to the Center of the Earth", are supercritical magma/gas mixtures erupting violently from the underground. According to the proposed model in areas with a thick earth crust or composed of resistant rock (the region of Tunguska is part of the basaltic Siberian Trapps) magmatic intrusions and gases tend to build up pressure until the rocks were shattered to pieces, hot gases can violently escape, ignite and causing an explosion.

Here some mystery mongering documentary - getting even the date wrong:



However the most compelling theory remains the impact of a natural extraterrestrial object. This hypothesis is supported by the reports describing a fireball descending on the Tundra in 1908, sedimentary features (the supposed presence of nanodiamonds, magnetic spherules and silicate spherules in the sediments of the swamp) and the pattern of the tree logs, supporting an explosion in midair.
There are some inconsistencies according to critics of the impact scenario: accounts of a series of thunders over a longer time period are hard to reconcile with a single impact (possibly various fragments ?) and the recovered sediments are not unambiguous (common background sedimentation or of not extraterrestrial origin ?) - the best evidence would be a fragment of the impactor.
In 2007 Luca Gasperini and his research team of the University of Bologna proposed a small lake as possible impact crater of a fragment of the meteorite that caused the explosion, lake Cheko is unusually deep unlike other lakes in the region and was apparently not reported previously of 1908 (however the region was poorly mapped and explored at the time). Also here the proposed evidence was not undisputed as seen in the response by COLLINS et al. 2008.
Only the discovery of material of extraterrestrial material on the bottom of the lake would be a decisive argument to settle the discussion of the mystery of Tunguska.


Bibliography:

COLLINS, G.S.; ARTEMIEVA, N.; WÜNNEMANN, K.; BLAND, P.A.; REIMOLD, W.U. & KOEBERL, C. (2008): Comment article Evidence that Lake Cheko is not an impact crater. Terra Nova 20: 165-168
GASPERINI, L.; ALVISI, F.; BIASINI, E.; BONATTI, E.; LONGO, G.; PIPAN, M.; RAVAIOLI, M. & SERRA, R. (2007): A possible impact crater for the Tunguska Event. Terra Nova 19: 245-251
GASPERINI, L.; BONATTI, E. & LONGO, G. (2008): Reply Lake Cheko and the Tunguska Event: impact or non-impact? Terra Nova 20: 169-172
GASPERINI, L.; BONATTI, E.;ALBERTAZZI, S.; FORLANI, L.; ACCORSI, C.A.; LONGO, G.; RAVAIOLI, M.; ALVISI, F.; POLONIA, A. & SACCHETTI, F. (2009): Sediments from Lake Cheko (Siberia), a possible impact crater for the 1908 Tunguska Event. Terra Nova 21: 489-494
RUBTSOV, V. (2009): The Tunguska Mystery. Springer-Publisher: 318

Enter the Coal Swamp Forest: The giant Lycopsid

"The "coal swamp" is one of the most powerful images in palaeontology. Dense, dark, and damp populated by strange trees, giant dragonflies, and sluggish tetrapods resting on rotting logs -a diorama can be found in almost every museum and is short-hand for the Carboniferous tropics. However appealing, this visual representation of the coal-swamp forest, based on analogy with modern tropical rainforests, is largely inaccurate."
W.A. DIMICHELE (2001): "Paleobiology II."

Fig.1. Illustration by Zdenek Burian for the book "Prehistoric Animals" (1956) showing a Carboniferous landscape - note in the background a dense forest of tree like lycopsids of the genus Lepidodendron.

Unlike modern forests, that are dominated by two large plant classes (tropical forests for example by angiosperms and boreal forests by gymnosperms) or by only a few species, the Carboniferous forest was composed of at least four classes and more than 10 orders of plants - with strikingly different morphology and ecology. The "Coal swamp" has therefore no modern analogy, despite the classic iconography is inspired mostly by modern Cypress swamps found for example in the modern Everglades of Florida.
Modern swamps and mires are characterized by a spatially gradient in nutrients and hydrology, these factors change also over time. The groundwater table is the dominant factor affecting the plant assemblage. Various fossil evidences show that the water level of the Coal swamp also strongly varied in time: preserved stumps are signs of an increase in the water table, killing vegetation and preserving it, charcoal layers show a decrease and drying up of the mire. The climate and therefore the environment of the Carboniferous swamp was not so monotonous as depicted in our imagination - there were phases of inundation and phases of drought.

Fig.2. Sketch of the outcrop in Victoria Park (Glasgow) preserving various stumps of Stigmaria (Lepidodendron) by Chris Meadows (1880).

The clubmosses, Class Lycopsida (or Lycopodiopsida) appear today as morphologically simple herbaceous plants, but are a very honourable and old group; fossil specimens reach back to the time when the first organisms colonized the dry land during the Silurian. Today more than 1.100 species are described, very similar in their basic morphology: from a horizontally creeping rhizome vertical branches grow straight upwards; these branches support the s
porangia (spore producing organs) and are covered by small scaly leaves.

Fig.3. The modern clubmoss Huperzia selago.

Fig.4. ... and the spikemoss Selaginella helvetica.

However during the Carboniferous several lycopsid groups achieved giant size and developed very different shapes - the dominant "tree" seen in most of the reconstructions of the Carboniferous Coal swamps is a giant lycopsid.
The genus Lepidodendron (or "scale tree"), a 35m high tree like lycopsid, was known for almost 200 years from the imprints of the "bark", showing a typical regular patter with the scars of the single leaves.
Despite its common appearance in most of the reconstructed landscapes of the Carboniferous epoch, Lepidodendron was surely limited in his geographical and temporal range. The plant was adapted to wet conditions, water transported also it spores - however such habitats were not characteristic for the entire Carboniferous, during the late Carboniferous the climate became drier and the genus Lepidodendron was replaced soon by smaller lycopsid genera, reaching almost 1 meter in height.

Today various different fossils were merged together to reconstruct the morphology of a Lepidodendron tree: The lower part of the stem, referred in the past as Knorria, was smooth, only the upper part, referred as Lepidophloios, was covered with small, needle shaped leaves (Lepidophylloides) similar to the branches of modern lycopsids. An important difference to modern lycopsids was the position of the sporangia - collocated at the end of dichotomously branching twigs and similar to a cone, known previously as the fossil genus Lepidostrobus.


However this reconstruction similar to a modern tree with stem and branches is valid only for a short phase of reproduction of the plant, when the organism finally produces a terminal sporangium. Until this phase it is more plausible assuming that Lepidodendron resembled much more a simple, unbranched lycopsid, forming very open forests with scattered small and large individuals.

Fig.5. Schematic reconstruction of Lepidodendron as adult, fertile individual and younger individual lacking branches with spore cones, probably the usual habit to be spotted in the Carboniferous forest. Depending from author and reconstruction method, the branches of the mature plant were displayed as standing upright or sag to the ground. The scale tree is named after the typical structure preserved on the bark - the leaf cushion - structure that supported small, needle like leaves covering the upper part of the plant.

To be continued...

Bibliography:


BRIGGS, D.E.G. & CROWTHER, P.R. (2003): Palaeobiology II. Blackwell Publishing: 583

SPINAR, Z.V. (1976): Quando l´uomo non c´era. Fratelli Fabbri Editori, Milano: 228

WILLIS, K.J. & McELWAIN, J.C. (2002): The evolution of plants. Oxford University Press - Oxford: 378

Accretionary Wedge #35: Giologia-Geognosie-Geology

"Broadly speaking, the short words are the best, and the old words best of all."
Sir Winston Churchill, British politician (1874 - 1965)

Evelyn is asking on her Georneys for everyone favourite Geology Word - what better word there is than the term that describes the knowledge of the anatomy of earth itself - the Geognosie, evolved today in the better known term Geology.

It was in the 18th and 19th century that common and noble men begun to gather natural curiosities in their cabinets or museum. The displayed natural oddities and specimen were collected mostly by lucky discoverers, paid assistants or conscripted students, only in later times also noble men started to go in the field by themselves, even is such activity was considered more a necessity to gather more specimen than to explore and understand nature.
The Swiss professor of philosophy Horace-Bénédict de Saussure (1740-1799) was one of the first to propose to the savants of the time the necessity to gain observations and exact measurements in the field. Savants was a general term adopted simply to well educated people interested in various abilities - philosophy, art and medicine, which often encompassed natural studies. People interested and dedicated to the new emerging fields of "Natural history" and "Natural philosophy" - fields trying to describe natural phenomena and infer their (mathematical) rules -were more specifically referred as "naturalists" and "natural philosophers".
Natural philosophy encompassed all observable phenomena in nature, from the physiological reaction of the body on the summit of Mount Blanc to the rocks composing the mountain. At the time it was very roughly divided in three sub-disciplines- zoology, botany and mineralogy, still the specimen (animals, plants and mineral) approach to nature is evident.


Fig.1. James Hutton (left) and Joseph Black portrayed as "philosophers" or early "geognosts": caricature publsihed in 1787 by John Kay (Edinburgh) (From RUDWICK 2005).

A much larger approach, to the structure of earth itself, was tried by a new science emerging from geography adapted to the necessities of the mining industries to understand the underground and the position of ore-bearing rocks

In Germany the science called "Geognosie" (earth knowledge) encompassed the description and representation of the surface of earth, like geography, but widened it approach to the third dimension, hidden in the underground. This science was referred also as "mineralogical geography" or "géographie souterraine", its goals are best understandable in the Italian name "anatomia della terra" - anatomy of earth.

Fig.2. Luigi Ferdinando Marsili "On the Structures of Mountains" (1705), early geognosts mapped and developed a classification scheme for the various landscapes observed in nature, however still a theorizing part was missing (from BATTISTA 2003).

However it was an applied, descriptive art, not a science in modern sense dedicated to formulate rules or hypothesis and test them. Geognosts went in the field to map the rocks of the countryside, theirs maps and profiles were a major input to create a new, a real science researching also theories.

Fig.3. John Clerk of Eldin (1728-1812) "Whinstone Dykes´by Fairlie, Firth of Clyde", a drawing of a Cliff in Scotland made in 1786. Eldin, a passionate amateur geologist tries in this wonderful depiction to sketch the position and direction of the basaltic dykes in the underground, merging a two-dimensional map with the third dimension, the profile (found in THÜSEN 2008).

Already Georges-Louis Leclerc de Buffon (1707-1788) stressed in his "Nature's Epochs" (1778) the need to create an own geotheory to understand the structure, the sediments, the fossils and in the end the history of earth. In fact Saussure tried to adopt this approach in his natural studies. In the same year of Buffon's "Epochs" the term geology was introduced (hesitant) in the literature by the Swiss naturalist Jean-Andre de Luc in his opus "Letters on Mountains".

"I mean here by cosmology only the knowledge of the earth, and not that of the universe. In this sense, "geology" would have been the correct word, but I dare not adopt it, because it is not in common use."

Fig.4. "I a geologist", from the Notebook M, 1838, page 39 of Charles Darwin, the full phrase as follows: "I a geologist have illdefined notion of land covered with ocean, former animals, slow force cracking surface &c truly poetical."

Geology became synonymous with the "Theory of the Earth" - a part of cosmology dedicated to the description of the character of earth and maybe more important it relationships with animals, plants and finally humans.

"In now addressing my brother -geologists - and under this term I would comprehend all who take an interest in the progress of a science whose problems are inseparably interwoven with the whole study of nature - I have been influenced by the conviction that it is good for us, as workers in the same field, occasionally to pause and question ourselves as to the ultimate bearing of our investigations."
David Page (1863): "The Philosophy of Geology."

However the word geology itself has older roots, even if other meaning - in his testament and legacy written in 1603 the Italian Renaissance- naturalist Ulisse Aldrovandi (1522-1605) introduces the term "Giologia" to refer to the study of "fossilia" - the things unearthed.
Aldrovandi had tried his whole life to classify nature - to separate rocks and fossils from the animals and plants the already existing term mineralogy was not sufficient - giologia would encompass all stones, all minerals and especially the petrified organisms (he recognized some fossils as once living beings) and also rocks nobody at the time could explain found on the surface of earth, but also excavated - again an tentative approach to consider the three-dimensional structure of earth.

Fig.5. The word "La giologia" in the official version of Aldrovandi´s will (from BATTISTA 2003).

200 years later the term, theory and principles of Geology will become largely known by the work of many fulltime geologists, like for example Sir Charles Lyell.

Bibliography:

ROSENBERG, G.D. (2009): The measure of man and landscape in the Renaissance and Scientific Revolution. In Rosenberg, G.D. (ed.): The Revolution in Geology from the Renaissance to the Enlightenment: Geological Society of America Memoir 203: 13-40
RUDWICK, M.J.S (2005): Bursting the limits of time - The reconstruction of Geohistory in the Age of Revolution. The University of Chicago Press, Chicago, London: 708
THÜSEN, J.v.d. (2008) : Schönheit und Schrecken der Vulkane - Zur Kulturgeschichte des Vulkanismus. Wissenschaftliche Buchgesellschaft, Darmstadt: 239
VAI, B. (2003): Aldrovandi´s Will: introducing the term "Geology" in 1603. In BATTISTA, G. & CAVAZZA, W. (2003): Four Centuries of the Word geology - Ulisse Aldrovandi 1603 in Bologna. Minerva Edizioni: 327

Plant Taphonomy

Plants can be preserved in the geologic record in various ways: as a mould, as compression/impression fossils, as permineralized fossils and even as unaltered plant remains.

- A compression fossil forms simply by plant remains that became embedde
d and buried by accumulating sediments. The water is squeezed out and the plant flattened. The original organic can be conserved as thin carbonaceous film forming a silhouette of the original plant or lost completely. In this case the rocks preserve only an impression of the former plant. This impression can be refilled by minerals, forming a "cast" of the original plant. In this kind of fossil the general morphology of the plant can be studied.

Fig.1. Rhacopteris asphlenites from the Carboniferous showing preservation by compression (carbonaceous film) and impression.

Fig.2. Fossil Ficus species from the Eocene lagerstätte of Bolca (Italy), here the original plant tissue was replaced by reddish coloured iron oxides.

Fig.3. Asplenium scolopendrium preserved as imprint in Holocene travertine. If such an imprint is refilled with other minerals a three-dimensional cast of the former plant can be formed.

Fig.4. Cast of a piece of wood composed of silica discovered in a volcanic tuff from the Permian.

Coal is a compression fossil in which the organic substance is enriched
in carbon and depleted by other volatile elements like hydrogen or nitrogen in various degrees, when plant remains are still visible it is classified as Lignite, when completely homogenized it is called Anthracite.

Fig.5. Example of coal in thin section, showing collapsed Megaspores, amalgamated plant fragments (Fusinite) and homogenous matrix.

- Permineralization is the classic petrifaction; the organic substance of the tissue is replaced by minerals deposited from percolating fluids. These minerals can be calciu
m carbonate, iron oxides or hydroxides, iron sulphides, silica, or - in cold environments - also ice. This kind of fossil is preserved undeformed and can deliver information about the three-dimensional structure of the plant.

Fig.6. Polished transverse section of a tree fern of the genus Psaronius, showing the structure of the false trunk, composed of roots growing together.

- Some tissues of plants are exceptional stable, like the cuticle covering the surface of a plant, or the Sporopollenin, organic substance forming the hull of spores and pollen grains. These components can be conserved, under the right conditions, unaltered for millio
n of years.
The epidermis and surface of plants possesses distinctive characters useful for taxonomic classification, like for example the superficial cell pattern, or the shape and distribution of the stomata, papillae and glands, spores and pollen grains also possess very
distinctive surface patterns.
If microbial activity is inhibited or oxygen not available also the less resistant plant tissues can be embedded in sediments and conserved unaltered. The most important fossils of this kind were recovered from lake sediments, amber and packrat middens.
In lakes due differences in temperature and density of the water the bottom
can became depleted of oxygen, preventing organisms to colonize and feed on organic material, also a rapid sedimentation quickly covers the plant remains, optimal conditions for fossilisation. Some lakes, especially swamps, contain also high concentration of organic substances, washed into the water from the land, that kill microbes, impregnate and preserve organic material.
Amber preserves organic material in various ways, when hardened resin has a limited mechanical protection effect, it protects the organism from scavengers and weather and isolates it from oxygen, which can oxidize the organic material or enable bacteria to destroy the inclusion. Resins of plants possess also an antibiotic effect and therefore kills microorganisms - in Egypt this effect was used to sterilize artificial mummies. The content of "sugar" in the resin probably also draw moisture out of the tissue, preventing further microbial activity.

Fig.7. Example of plant tissue preserved in amber, trichomes of a oak tree florescence.

Despite these cases it is very rare that a plant becomes completely fossilized - especially large plants, like trees, tend to be embedded in sediments only in fragments.
This causes major problems; some plant tissue tends to be overrepresented in the fossil record. For example wood and bark are more resistant than non lignified plant tissue and will became fossilized more easily - this can produce the effect that herbaceous plants are generally underrepresented in the geologic record. In contrast leaves or pollen
are produced in great quantities even by a single plant, this can produce a bias of the stratigraphic record to some species of plants.

Fragmented plant remains also make it difficult to reconstruct the overall morphology of a single plant species, and worse, cause a proliferation of artificial plant species. A single plant can produce diverse organs and tissue and therefore fossils - like foliages (which often various shapes and sizes on a single individual), roots, stem, branches, bark, male or female cones in gymnosperms, blossoms and fruits in angiosperms.
Many fossils were found dissociated and attributed to individual species, only subsequent discoveries revealed in some cases which tissues belong together, forming a si
ngle plant species. For example the extinct Lepidodendron-tree, related to the modern Lycopsids, was reconstructed by merging together at least seven single "species" (Stigmaria - roots, Knorria - bark, Lepidophloios - bark, Lepidostrobus - cone, Lepidophylloides - leaf etc.) based on the single organs or tissues of the former plant.

Also fragments of plants not necessarily represent a real association of plants - a biocenosis. Plants or parts of them can be transported by wind (for example lea
ves) or by water (for example wood), therefore plant species of various regions and ecosystems can became deposited and mixed together in a sedimentary basin. This false association of plants is called taphocenosis - a death assemblage.

Fig.8-10. Litter in a modern forest, showing fragmentation of a single or few tree species in various "morphospecies" based on the single plant organs, like cones, needles, branches, wood, intermixing with herbaceous plants and even stranger live forms as fungi are, forming possibly in the geologic record a future taphocenosis.

Many reconstructions of former landscapes show an incredible biodiversity of plants mixed chaotically together, but observing modern landscapes we note that most plant associations are characterized by few plant species, dominating a specific habitat and that there is a continuum of various habitats following in succession. We will, for example, find a specific plant-association on a shore, and a specific plant-association on the dry highland.

Fig.11. "Coal swamp" as imagined by Z. Burian in 1972 (found in SPINAR 1976).

A concrete example of the biased reconstruction of the former vegetation is the classic and in textbooks ubiquitous "coal swamp", that I will discuss soon…


Bibliography:


BENTON, M.J. & HARPER, D.A.T. (2009): Introduction to Paleobiology and the Fossil Record. Wiley-Blackwell Publication: 592

WILLIS, K.J. & McELWAIN, J.C. (2002): The evolution of plants. Oxford University Press - Oxford: 378

SPINAR, Z.V. (1976): Quando l´uomo non c´era. Fratelli Fabbri Editori, Milano: 228


Online Resources:


ARENS, N.C. et al. (1998): Plant Fossils and Their Preservation. (Accessed 18.06.2011)

Paleomammologist George Gaylord Simpson

"The known specimens of Mesozoic mammals are among the most precious and important remains of extinct life which have yet been discovered. They are the sole direct evidence of the fundamental first two-thirds of evolution of the Class Mammalia, which is now dominant on the earth and to which we ourselves belong. This importance has long been rather vaguely recognized, but it can hardly be said to have been properly evaluated. The Mesozoic forms are usually briefly dismissed as being rare, fragmentary, and poorly understood - accusations which are true, but not in the accepted degree."
Introduction to SIMPSON, G.G. (1929): "American Mesozoic mammals".

George Gaylord Simpson
(1902-1984) was born in Chicago in a religious family, but already in childhood he rejected religion as childish behaviour and displayed an intense interest in facts.
At age 16 he entered University to become a writer, but in the second year he enrolled in a geology course, and following the advice of his instructor Arthur Tieje he changed to Yale University as the best place to study geology and palaeontology. Here, in the basement of the Peabody Museum, he discovered a large collection of yet not studied Mesozoic mammals, but his advisor, Richard Swann Lull, despite the enthusiasm and abilities displayed by Simpson, mistrusted him: "those fossils are much too important very delicate and highly significant for a young graduate student."
Only in the following year, after a successful field season in Texas and New Mexico, where Simpson discovered fossils of Pliocene and Miocene mammals, Lull permitted Simpson to approach the valuable fossils (and despite one initial accident, when Simpson stumbled over one of the first fossils to be recovered, breaking it).

After his graduation from Yale, Simpson went to the Natural History Museum in London, where he continued his studies on the bones of early mammals, comparing the American to the European species - the results were important monographs of the evolutionary relationships of the various groups.

Fig.2. Figure of the dentition of various American Mesozoic mammals, published in SIMPSON, G.G. (1929): "American Mesozoic mammals", one book in which he summarize the results of his intense studies on fossils from America and Europe.

In 1927 back to America, he joined the American Museum as assistant curator of fossil vertebrates, position inherited from his former mentor.
Simpson continued his work on the taxonomy of mammals, but begun also to introduce theoretical methods and concepts in palaeontology.
In the years 1942 to 1944 he fought in World War II and was sent to Nord Africa, Sicily and Italy, obtaining the rank of major.
After the war he returned to the United States, becoming professor of vertebrate palaeontology at Columbia University and later curator for the Museum of Comparative Zoology at Harvard University.


Simpson popularized palaeontology and evolution with various books for the general public, but also contributed to a general synthesis of evolution by proposing that small genetic variations in populations are in fact the breach on which natural selection can act, and that therefore the observed chance in the fossil record is explainable by evolution. It is again the irony of history that George Gaylord Simpson, like Darwin or Gould, is apparently one of the most quote-mined evolutionists by creationist in the Internet…

Online Resources:

RYAN, M.J. (16.06.2011): Born This Day: George Gaylord Simpson. (Accessed 16.06.2011)
Cover picture from LAPORTE, L.F. (): George Gaylord Simpson - Paleontologist & Evolutionist 1902-1984. (Accessed 16.06.2011)
LAPORTE, L.F. (2004): Rock Stars George Gaylord Simpson (1902-1984). GSA TODAY September 2004: 16-17

15, June 1991 : The Pinatubo eruption climax

Pinatubo (Philippines) was, despite some activity of fumaroles, not considered an active or dangerous volcano.
Apr
il 2, 1991 an initial explosive eruption phase occurred on a 1,5 kilometre long fissure, until June 8, the eruption changed to a more effusive type with a climax June 15, when the eruption plume reached a height of 20.000 meter. Subsequent research showed that deposits of pyroclastic flows and lahars can be found up to 20 kilometres distant to the mountain. These deposits were dated to approximately 5.100-4.400, 3.000 to 2.300 and 600-400 years, the entire volcanic edifice of Pinatubo and its base is dated at least to 1,1 million years.
Historical eruptions were however not known; a possible event in the year 1531 or 1561 is assumed but not confirmed by accounts or local stories - the slopes of the mountains were also for centuries occupied by the local tribe of the Aetas.


Despite the intensity of the eruption, only estimated 700 to 1.000 victims were count. The evacuation zone around the volcano was increased from 20 to 30 kilometres, pyroclastic flows were observed up to a distance of 14 kilometres; more dangerous were lahars that endangered places up to 50 kilometres distant. The eruption of Pinatubo lasted until September 1991, it formed a 2 kilometre large caldera and lowered the mountain by 100 meter.
Notable was the influence of aerosols and sulfur dioxide of the eruption plume on the worldwide climate -these components are thought to have cooled the global temperature by 0.25°C.


Online Resources:


KLEMETTI, E. (15.06.2011): The 20th anniversary of the eruption of Pinatubo in the Philippines. (Accessed 15.06.2011)

Cover picture from USGS (1991): Vertical eruption at Pinatubo, 1991. (Accessed 15.06.2011)

A women geoscientist in the Dolomites: Maria Matilda Ogilvie Gordon

The Scottish Maria Matilda Ogilvie Gordon (1864-1939), or May as she was known, was the oldest daughter of a pastoral family composed of eight children, five boys and three girls.
The parents had good connections and friends in various schools and colleges - all the surviving children (one died in infanthood) experienced a profound education. Maria entered Merchant
Company Schools' Ladies College in Edinburgh at age of 9. Already in these early years she showed a profound interest in nature, so during holidays she enjoyed to explore the landscape of the Highlands accompanied by her elder brother, the later geologist Sir Francis Ogilvie.
May aspired to become a musician and at age 18 she went to London to study music, becoming a promis
ing pianist, but already in the first year her interest to nature prevailed and she decided for a career in science.
Studying both in London and Edinburgh she obtained her degree in geology, botany and zoology in 1890. Maria Ogilvie hoped to follow-up their studies in Germany, but in 1891, despite efforts and friends, even by the famous geologist Baron Ferdinand Freiherr
von Richthofen (a pioneer geologist of the Dolomites), she was refused at the University of Berlin - as women were still not permitted to enrol for higher education in England and Germany. She went to Munich, where she was received friendly by eminent palaeontologist Karl von Zittel (1839-1904) and zoologist Richard von Hertwig (1850-1927), in contrast mineralogist Paul Heinrich von Groth (1843-1927) refused to allow the young women to enter his laboratory. Maria Ogilvie was not allowed to enrol in a regular course of studies even at Munich, research was done as private person and to listen to lectures she had to sit in a separate room with the doors half-open.

In July 1891 the couple von Richthofen invited her to join a 5-
week trip to the nearby Dolomites Mountains, visiting the Gröden-Valley.
From the first day Maria Ogilvie was immensely impressed by the landscape and soon she started an intense exploration of the area. She learned rock climbing and visited the Mecca of geology, the small village of Predazzo. Richthofen introduced Maria Ogilvie to alpine geology, and the travel party visited the meadows of Stuores in the Gader-Valley. At the time Maria Ogilvie had studied modern corals and was inclined to become a zoologist, but Richthofen, maybe also after showing her the beautiful preserved fossil corals of Stuores, advised her to become rather a geologist and to study and map this area.


Fig.2. View of outcrops of marls on the Stuores pasture.

Richthofen was over 60 and therefore he couldn't provide much support in the field, Maria Ogilvie remembers the challenge and danger of field work, sometimes accomp
anied by a local rock climber named Josef Kostner:

"When I began my field work, I was not under the eye of any Professor. There was no one to include me in his official round of visits among the young geologists in the field, and to subject my maps and sections to tough criticism on the ground. The lack of supervision at the outset was undoubtedly a serious handicap."
(Ogilvie Gordon 1932)


For two summers she hiked, climbed and studied various areas in the Dolomites and instructed local collectors to carefully record and describe their fossil sites.
In 1893 she published the results in an article titled "Contributions to the geology of the Wengen and St. Cassian Strata in southern Tyrol", where she, as gifted drawer, published not only detailed figures of the landscape of the Dolomites, but also important contributions to the, at the time still poorly know, stratigraphic record of the Dolomites, establishing marker horizons and describing the ecology of var
ious fossil corals associations. She alone described 345 species from the today 1.400 known species of molluscs and corals of the Wengen and St. Cassian Formations.
The published paper, extract of their thesis "The geology of the Wengen and Saint Cassian Strata in southern Tyrol", finally earned her respect by the scientific community, and more important: her DSc degree in 1893 from the University of London
(times finally had changed)- the first female DSc in the United Kingdom.

The same year she returned into the Dolomites to proceed with her geological and paleontological research and in 1894 she published her second important contribution, the "Coral in the Dolomites of south Tyrol." Therein Maria Ogilvie emphasized that the systematic of corals must be based on microscopic examination and characteristics, not as usual done at the time simply on superficial resemblance.


In 1895 she returned to Aberdeen, where she married a longstanding admirer, the physician Dr. John Gordon, husband who (unusual for the times) respected and encouraged her passion for the Dolomites. He and the four children accompanied Maria Ogilvie, despite the difficulties of travels, on various excursions into the Pale Mountains.

In 1900 she returned to Munich, becoming the first woman to obtain a PhD at the local University for her previous work in this city (also in Germany times changed). As thank to her old mentor, palaeontologist von Zittel, she translated his extensive German research on the "Geschichte der Geologie und Palaeontologie" into English as "The History of Geology and Palaeontology."

Maria Ogilvie continued her studies and continued to publish, mostly privately. In 1913 she was preparing an ulterior important work about the geology and geomorphology of the Dolomites, to be published in Germany, but in 1914 with the onset of World War I and the death of the publisher the finished maps, plates and manuscripts
were lost in the general chaos.
This was a hard setback, but like so many times before Ogilvie would not surrender. In 1922 she returned into the Dolomites, where she encountered the young palaeontologist Julius Pia, who, during the war, had carried out research in the Prags Dolomites. Both became friends, and in 1922 to 1925 they explored many times together the Dolomites.
She published copious volumes of the tectonic evolution of the Dolomites, and also books of geology for the interested layman, hoping to share her fascination of the Dolomites with others - one of the first examples of modern geological guide books for the region.


Fig.3. and 4. Landscape profile (and recent photography) of the Langkofel-massif after a drawing from GORDON & PIA (1939): "Zur Geologie der Langkofelgruppe in den Südtiroler Dolomiten."


Maria Matilda Ogilvie Gordon succeeded against all odds and unequal treatment of women to study geology and achieve important results in this field. Still today, mapping in the field, many observations of Maria can only be confirmed by modern geologists - also I based some of my field work on her heritage.

To remember her contributions in paleontology in 2000 a new fossils fern genus discovered in Triassic sediments of the Dolomites was named after Maria Gordon - Gordonopteris lorigae.


Bibliography:

WACHTLER, M. & BUREK, C.V. (2007): Maria Matilda Ogilvie Gordon (1864-1939): a Scottish researcher in the Alps. In BUREK, C. V. & HIGGS, B. (eds): The Role of Women in the History of Geology. Geological Society: 305-317

A geologist riddle #19

A new mysterious photography - not always is what we see also what we should believe...

Roy Chapman Andrews and the Kingdom of the Cretaceous Skulls

Modern pop-culture legends tells that one of the most well-known adventurers and archaeologists in movie history, Dr. Henry Walton Jones, Jr. - or Indiana Jones ("who becomes 30" this very day), was loosely based on real naturalists, one of them adventurer and mammologist Roy Chapman Andrews.



Fig.1. "Roy Andrews Chapman on "Kublai Khan", from ANDREWS 1921.

Roy Chapman Andrews (1884 -1960) was an American explorer, adventurer, naturalist, studied mammologist and later director of the American Museum of Natural History.
In his youth he financed his study by offering services as a taxidermist, a self-taught art. After graduation he tried to get a job at the Natural History Museum, but there were no position vacant. Chapm
an however did not surrender and responded that he was even willing to clean the floors, if this could him bring into the museum.
Surprised by such ardour, he was hired as janitor and assistant taxidermist. Maybe mocking him in friendly way he was assigned every morning to mop the floors in the taxidermy studio; the afternoons were then devoted to real taxidermy.


However by incessant work and an incredible enthusiasm he managed to lure attention on his persona and he was granted a raise in salary, a full time job as taxidermist and asked to guide guests to the muse
um. In 1907 he was send on his first expeditions. February 7, a whale was washed ashore of Long Island and the museum hoped to recover the skeleton. Chapman and a colleague were send to the site, where they discovered that a storm was slowly, but incessantly covering the carcass with sand. For two days they fought the cold sea and the icy wind, only after a week finally with the help of local fishermen the skeleton could be recuperated.

Andrew visited Japan and China, where he collected animals and experience of the Far East. In 1920 he achieved to persuade palaeontologist and museum president Fairfield Osborn to finance an expedition into Asia in search of fossils of the early ancestors of major mammals' lineages, including humans.
Between 1922 and 1939 Andrews and his team carrie
d out five expeditions into previously poorly mapped or unknown areas of Central Asia , a vast desert plagued by blizzards, sandstorms, snakes, flash floods, bandits, civil war and an insecure political equilibrium.
The goals of the expeditions, carrie
d out with a odd combination of early automobiles and camels, was to recover geographical, archaeological, botanical, zoological and geological information, but especially fossils of early hominids.

Fig.2. "Relief map of Mongolia showing routes, Central Asiatic Expeditions, 1922-1930.", from ANDREWS 1932.

Fig.3. and 4. "Camel and motor car tires" and "Andrews and Tserin at Hatt-In-Sumu, 1928" from ANDREWS 1932.

One of the most important discoveries of the expedition was achieved by chance - Chapman got lost in the monotonous plains and asked direction to a military outpost, meanwhile the photographer of the team, John B. Shackelford, stumbled upon a cliff edge, where he noted some fossil bones. They discovered bones of dinosaurs and mammals, and also an egg, thought to be from a bird. Only hours after the discovery of the site the expedition was forced to turn back - winter was approaching fast in the Gobi - but they decided to return the next years.

Fig.5. "The Flaming Cliffs of Djadokhta" (Southern Mongolia), type locality of the Upper Cretaceous Djadoktha Formation, from BERKEY & MORRIS 1927.

In the cliffs of red glowing sandstone, named appropriately by Chapman "Flaming Cliffs", they discovered what would become part of the history of palaeontology: various previously unknown dinosaur species - like the gryphon lookalike Protoceratops, or the birdlike Velociraptor, but most scientifically spectacular - rare bones and skulls of Cretaceous mammals, like Zalambdalestes, Djadochtatherium, and Deltatheridium, and oddly enough clusters of large fossil eggs. Eggs of dinosaurs were extremely rare, previous of Chapman only one site on the French Riviera was known with such fossils.

Fig.6. "The first nest of dinosaur eggs, discovered by Georg Olsen at Shabarakh Usu in 1923. Two eggs and part of another are shown lying on the surface. the small sandstone ledge in the background was removed intact and sent to the Museum. In the center of the block of stone thirteen other eggs were discovered, 1923", from ANDREWS 1932.

Roy Chapman Andrews was a gifted storyteller; he published various accounts of his expeditions and loved to set up his perception in the general public as an adventurer, in his 1935 book, appropriately titled "This Business of Exploring", he wrote

"I was born to be an explorer...There was never any decision to make. I couldn't do anything else and be happy."


There are various possible allusions in the Indiana Jones movies to the life of Roy Chapman Andrews. Indiana Jones is introduced in the first movie "The Raiders of the Lost Ark" (1981) venturing to Nepal, like Andrews ventured in the Far East. Jones most recognized attributes comprises a 38 colt and a fedora hat, various expedition photos of Andrew show him with a broad rimmed hat and during expeditions he loved to hunt animals, for collection or cooking, but also used his pistols to defend the team from bandits.
However both producer G. Lucas and director S. Spielberg based the movie and the fictional character mainly on their impressions of matinée serials and pulp magazines of the 1930´s and 1940´s, there is no official confirmation that Indiana is based on a single or a true historic character. But Andrews (and many other naturalists and explorers of the 18th and 19th century) without doubt influenced by his discoveries, accounts and especially books the general view and love of the public and authors to adventurers, so in a certain manner he became part of the Indiana Jones universe (and let us admit, who was not inspired a bit by the Indy-style ?)



Bibliography:

ANDREWS, R.C. (1921): Across Mongolian Plains - A naturalists account of China's "Great Northwest". D. Appleton & Company: 276
ANDREWS, R.C. ed. (1932): The New Conquest of Central Asia - A narrative of the explorations of the Central Asiatic Expeditions in Mongolia and China, 1921-1930. Natural History of Central Asia Vol.I.; The American Museum of Natural History New York: 678

ANDREWS, R.C: (1935): This Business Of Exploring. G.P. Putnam´s Sons, New York: 288
BERKEY, C.P. & MORRIS, F.K. (1927): Geology of Mongolia - A reconnaissance report based on the investigations of the years 1922-1923. Natural History of Central Asia Vol.II; The American Museum of Natural History New York: 474
GALLENKAMP, C. (2001): Dragon Hunter - Roy Chapman Andrews and the Central Asiatic Expeditions. Penguin Group, New York: 344
NOVACEK, M. (2002): Time Traveler: In Search of Dinosaurs and Ancient Mammals from Montana to Mongolia. Farrar Strauss and Giroux: 352

A very short history of Paleobotany

"There are so many plants on the earth, that there is a danger to thinking them trivial...[]...What a marvellous cooperative arrangement, plants and animals each using the others waste gases, the whole circle powered by abundant sun light. But there would be carbon dioxide in the air, even if there were no animals. We need the plants much more then they need us."
Carl Sagan in "Cosmos", ep. 2 "One Voice in the Cosmic Fugue"

Fig.1. A modern fern blade compared to a fossil of the Carboniferous (almost 300 Ma) from Southern France.

Plant fossils are possibly the first petrifactions recognized as the remains of once living organisms - many fossils species still resemble extant species and it was therefore straightforward to compare and match them together.
Already in 1699 the English naturalist Edward Lhwyd (ca. 1660-1709) depicted various fossil plants in his catalogue of the English fossil titled "Lithophilacii Britannica ichnographia". Also Carl von Linné (1707-1778) studied and published some notes about plant fossils
hosted in the cabinets of curiosities of Swedish noblemen.
The oldest publication dealing almost exclusively with plant fossil
s is however the "Herbarium diluvianum" by the Swiss scholar Johann Jakob Scheuchzer, published in various edition in 1709 and 1723.

Fig.2. Plate from J.J. Scheuchzer´s opus magnus "Herbarium diluvianum" (1709-1723).

Scheuchzer published his studies and observation of many fossils plants coming from the English Carboniferous, the Permian of Germany and the Swiss Cainozoic, including plant casts found in travertine. He argued that these imprints were once living plants like recent ones that became buried in sediments by the biblical flood. His was so convinced of the similarities of fossil to moder
n plants that he even tried by phenology to determinate the month when the flood occurred.

Unlike bones, shells and ammonites, collected and studied avidly by amateurs, paleobotany was since its early origins dominated by professional scholars - the identification of fossil plants requires apparently more skills and profound knowledge in modern botany, abilities or interests not encouraged enough in all times?

Fig.3. Plate from Caspar von Sternberg´s "Versuch einer geognostisch-botanischen Darstellung der Flora der Vorwelt" (Attempt to a geognostic-botanical representation of the flora of the ancient world) (1820-1838), showing the "bark" of an extinct Lepidodendron-"tree" related to the modern Lycopsids.

In 1804 the German Geologist and Palaeontologist Ernst Freiherr von Schlotheim (1764-1832) published a description of Permian plants "Beschreibung merkwürdiger Kräuter-Abdrücke und Pflanzen-Versteinerungen" (Description of curious imprints of herbs and plant-petrifactions), where he adopted on the fossil plants the systematic-system developed by Linné and compared their ecology to modern plants, establishing finally the principles of modern Paleobotany.
Important contributions to botany of fossil plants and pollen grains and there use in stratigraphy came from the French geologist Alexandre Brongniart (1801-1876 - with Cuvier one of the first to draw startigraphic profiles in Europe) with his "Histoire des vegetaux fossiles, ou recherches botaniques et geologiques sur les vegetaux renfermes dans les diverses couches de globe"(1828-1838).

Fig.4. Plate from A. Brongniart´s "Histoire des vegetaux fossiles" (History of fossil plants) (1828-1838).

After the first general works on paleobotany surprisingly fast more specific research on single formations, geographical areas or plant groups was published, for example the German Heinrich Robert Göppert (1800-1884) studied the Tertiary brown coal deposits and the Austrian physician Franz Unger (1800-1870), after becoming professor for paleobotany in Graz and Vienna, studied the coal deposits of Styria. In his "Iconographia plantarum fossilium" he compares the fossil flora with the forests of Indonesia, South America, the Caribbean and Mexico, recognizing that the plants indeed can be used to reconstruct the climate of a tropical past - it is no wonder that geologist Henry de la Beche (1796 -1855) collocated "Professor Ichthyosaurus" in a tropical jungle with palm-trees and gigantic ferns.

Fig.5. Plate from H.R.Göppert´s "Die Tertiärflora auf der Insel Java" (Tertiary flora of Java) (1854).

To be continue...

Online Resources:


ROBERTS, B.F.; SHARPE, R. & WATT, H. (): Edward Lhwyd. (Accessed 09.06.2011)