Palaeontology and Myth: The terrible Leviathan

Sometimes palaeontologists when naming a new species got inspired by myths and legends told in ancient and modern stories.

When the first fossils were found in the desert of Peru, researchers thought they had discovered the tusks of an elephant, but the remains, fragments of the skull and teeth, are parts of a 14m long whale of the Miocene (ca.12-13Ma). The fossils were discovered in 2008 in the desert of Pisco-Ica, southern Peru, and are now described and published in an article in the journal Nature.
Among the remains the jaw with 29 teeth is the most remarkable feature, single teeth reach a length up to 36cm and a width of 12cm, the largest whale teeth known so far.

Fig.1. Schematic representation of the recovered fossils, skull in dorsal (a) and ventral view (b) mandible in dorsal view (c) side view of the jaw attached to the skull (d) dentition of L. melvillei, h+i modern sperm whale teeth, figure from LAMBERT et al. 2010

The new species, which also represents a new genus, has been provisionally named Leviathan melvillei, the genus name is inspired by the story of the mythological sea monster in the Bible and the species is a tribute to author Herman Melville, known for his novel on Moby-Dick.
According to some online remarks however the name Leviathan is already occupied by a kind of North American proboscid (KOCH 1841).
According to the published research the animal is comparable in his overall anatomy to the modern sperm whale (Physeter macrocephalus), the largest existing teeth-whale, the impressive teeth suggest that the new species was a specialized to hunt large prey. Modern sperm whales have relatively small teeth, since they prefer to feed, by “sucking” them in, on large cephalopods.
Considering the size of the jaw and the teeth of L. melvillei however, the researchers speculate that it hunted smaller whales, a prey worth of a hungry Leviathan.

Fig.2. Reconstruction of Leviathan melvillei (14m long) in the act of preying on a smaller mysticet (7 to 8m long), because of the fragmentary remains of the skull the appearance is speculative, and based mainly on the alleged relationship with the modern sperm whale, figure from NatureNews.

References:

LAMBERT, O.; BIANUCCI, G.; POST, K.; DE MUIZON, C.; SALA-GISMONDI, R.; URBINA, M. & REUMER, J. (2010): The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru. Nature Vol. 466: 105-108 doi:10.1038/nature09067

Alpha...directions: Earth and Evolution meets Pop Culture

From the "Big Bang" to our ancestors - and all this in form of a comic book with 360 pages.
The German cartoonist Jens Harder tries a simply task: to tell the geological history of earth and life in pop culture style: he mixes scientific facts with myths and icons of ancient and modern civilisations, so fossils encounter the Venus of Botticelli and skyscraper rise from a continental rift, as a result of this billion years long tale: "Alpha...directions".

Fig.1. Figure from here

Fig.2. Figure from here

The Matrei zone - the southern margin of the Penninic ocean

The nappe theory developed in the Western Alps, but was soon exported to the Eastern Alps, and then to the rest of the globe, by the Swiss geologist Emile Argand (1879 - 1940), who between 1909 to 1916 draw the first profile of the Penninic zone and then represented the structural setting of the entire Western Alps in a 1:500,000 tectonic map and corresponding cross-sections.

Argand's Penninic zone was a stack of six recumbent fold-nappes, made up of a basement core and mantled by Mesozoic sediments. Based on these profiles he developed a formation model who applies to all mountain ranges: the theory of embryotectonics suggests that single nappes are the results of the compression of a chain of sedimentary basins and their infills (he incorporated the existing idea of an Alpine geosyncline), who pushed together became stacked and finally folded.

Fig.1. Argand's generalized view of the Europe-vergent Alpine belt (figure from DalPIAZ 2001).

In this theory the observed amphibolites or serpentine bodies, found intercalated in the Bünder Schists throughout the Alps, where injections and submarine effusions of mafic-ultramafic melts which were supposedly emplaced during orogenic contraction.

Fig.2. Argand's (1916) diagram of the western-Alpine geosyncline during its initial contraction (embryotectonics) with syn-orogenic emplacement of ma?c magmas (black, Piedmont ophiolites) along the sheared lower limb of the Dolin-Dent Blanche geoanticline. Simplifyed legend: (1) rigid foreland, (2) epicontinental basin, (3) Valais foredeep, (4) Gran St. Bernard cordillera, (5) Piedmont basin, (6) Dolin-Dent Blanche cordillera (figure from DalPIAZ 2001).

Argand's theory resolved many geological contradictions (like the to complex reconstruction of double-folds), and seemed supported by the general north to south symmetry of the geological units in the Alps, but his assumption of continuous nappes could not explain some geological abnormalities, who have no symmetrical equivalent on "both sides" of the Alps or show a very complex pattern of different rocks.

At the southern boundary of the Penninic to the Austroalpine units a zone with a variegated rock inventory is situated. Surrounded by mainly calcareous phyllites, typical for the development of the Bündner schists, horizons of breccias, turbiditic sediments and blocks of reworked (Lower) Austroalpine rocks are intercalated. Also quartzites, calcareous and dolomitic marbles, and rauhwackes are accompanied by serpentinites and their associated rock types.

Some of these formations are highly tectonized and fault zones separate the so-called Matrei zone from surrounding tectonic units.

Fig.3. Geological map of the southern border of the Tauerm Window, with the so-called Matrei-Zone.
AUSTRO-ALPIN + PENNINIC
Td Dolomite and limestone - marble (middle and upper Triassic)
Tp White Quartzite (upper Permian - lower Triassic)
Mf Schist and phyllite with Mica (Cima-Dura-Series, Paleozoic)
PENNINIC
a3 Prasinite/Amphibolite with Epidote, Biotite, Chlorite (Matrei Zone)
Cs Calcareous schist (Lias)
from: Giorgo del PIAZ (1928-1930): Carta Geologica delle Tre Venezie, Foglio 4b. Monguelfo.

Fig.4. Tectonized phyllite of the Cima-Dura Series, some meters before the contact to Triassic marbles.

Fig.5. Overview to the north, strong tectonized contact between schist/phyllite of the Cima-Dura Series, part of the Austro-Alpine, to Triassic marble (white escarpment), already part of the Tauern Window. The steep contact plunges directly to the valley floor W-E.

Fig.6. Triassic marble on the valley floor.

Fig.7. Prasinite with layers of epidote and quartz from the Matrei Zone.

With the formulation of the theory of continental drift at the beginning of the 20th century, an his modern modification in form of plate tectonics, today the Matrei zone is explained as a tectonic melange zone, it is not a nappe in the sense proposed by Argand, but an intermingled "plaice", formed during the orogenesis, representing the uppermost transition zone of the Penninic nappes. The slices and blocks of sedimentary rocks can be explained as olistolithes, which glided from the southern continental margin into the Penninic deep-sea sediments. The serpentinites (thought by Argand of syndeformational formation) were scraped off from the ocean floor and brought to the surface. Therefore, the Matrei zone can be interpreted as an expression of the closing processes of the (single) Penninic Ocean in the Cretaceous. Due to the northward drift of the Austroalpine units, the Penninic oceanic crust was subduced into the earth's mantle below the Adriatic microcontinent. In this course parts of the oceanic floor were sliced off and incorporated in an accretionary wedge at the surface. Large blocks of the sedimentary cover of the overthrusted Austroalpine unit broke off and slided through the continental slope to the deep-sea floor. Turbiditiy currents and coarse-grained debris-flows covered these blocks. Once incorporated into the accretionary prism of upthrustet material, the entire rock succession was extremely deformed.

References:

DalPIAZ, G.V. (2001): History of tectonic interpretations of the Alps. Journal of Geodynamics 32: 99-114
STINGL, V. & MAIR, V. (2005): An introduction to the geology of South Tyrol. Provincia Autonoma di Bolzano-Alto Adige - Ufficio geologia e prove materiali: 80

Geology and Cyclicity: Milankovitch´s idea

"I do not think that's my duty to teach to the ignorant the most basic things, and I have never forced anyone to accept my theory, on so far nobody could expose something."

Milutin Milankovitch in 1950

Milutin Milankovitch (1879 - 1958) was born in a relatively wealthy Serbian family, so it was almost a kind of obligation for him to archive a higher education degree and later take over the family business. So he studied agriculture, but following a passion for natural sciences he went to Vienna, where he in 1904 concluded his studies as an engineer.
Five years later he returned to Belgrad where he found employment as professor for mathematical studies at the University. Like Croll he was in search of a scientific problem worth his efforts, and in 1911, sharing some presumably good wine with a friend, he decided to develop a mathematical theory to explain climate changes on the planets of the solar system.

He studied the work of Croll, recognized his previous achievements but also noted his insufficient data. Milankovitch also consulted the work of the German mathematician Ludwig Pilgrim, who in 1904 published exact calculations of the orbital eccentricity, earth's obliquity and the rotation of the axis of earth (change of the perihelion). Pilgrim also tried to correlate the eccentricity with the occurrence of ice ages.
Between 1912 and the beginning of World War I Milankovitch published some preliminary abstracts of his developing theory, concluding that all three factors, in contrast to previous authors, are important to explain earth's climate. At the beginning of the War, Milankovitch was arrested as Serbian officer and imprisoned in his hometown Daly, but fortunately he was carrying with him his work, and so even in the first night as prisoner he continued to work. "When after midnight I looked around in the room, I needed some time to realize where I was. The small room seemed to me like an accommodation for one night during my voyage in the Universe."Soon after he was released and travelled back to Belgrad, where he continued his work during the entire War and published some ideas about the climate of Mars and Venus.

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

Fig.1. Variations in the Earth's orbital parameters:
1. Eccentricity: the shape of the orbit around the sun.
2. Changes in obliquity: changes in the angle that Earth's axis makes with the plane of Earth's orbit.
3. Precession: the change in the direction of the Earth's axis of rotation, i.e., the axis of rotation behaves like the spin axis of a top that is winding down; hence it traces a circle on the celestial sphere over a period of time.
Together, the periods of these orbital motions have become known as Milankovitch cycles. These parameters influence the amount of solar energy on earth´s surface, especially during summer of the northern hemisphere (55°-65°N).

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

The German meteorologists Wladimir Köppen and Alfred Wegener supported the new theory, and noted the apparent coincidence of the calculated curve with the by Penck and Brückner postulated four European glaciations.

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

Fig.3. Outcrop of the Trubi-Formation at Capo Spartivento (South-Italy), a succession of Globigerina-marls from the Pliocene-Pleistocene transition. The regular stripes are caused by organic rich layers, thought to be caused by changes in the biological productivity in response of changes in solar insolation - and so of the astronomical parameters - the Milankovitch cycles.

References:

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

Resources:

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

Increasing interest in studying Erosion

Erosion is a natural process in which by means of chemical, physical and biological processes rocks get dismantled and altered. Most rocks form under very different conditions then reign on Earth's surface, and they tend to adapt to these new conditions by erosion. In granite the feldspars and micas tend to be altered chemically to clay-minerals, quartz is more resistant, but also tends to decompose and will be rounded by transport and mechanical erosion. To understand erosion is not only significant for geologists, but has also significance for engineering, agriculture and so for society, for example to prevent soil degradation and limit the sedimentation in canals or reservoirs.

Here I present a German study published in 2007 that evaluates the research on “erosion” (without specifying exactly what they mean, I assume all kind of erosion in all environments).

Considering the numbers of publications dealing with the subject the United States (4.522) prevail with a large lead of 2.600 publications over the United Kingdom (1.895) and other countries. After France, with 1.264 publications, we fall under barely below the limit of 1.000 publications, with Canada (996) and Germany (983). Even summing up the remaining countries (Australia, China, Italy, Spain and Japan, with a total of 3.447) the American peak can not be reached.

Fig.2. Number of publications per country dealing with erosion between 2000-2005 (after MITTERMAIER et al. 2007).

Research and publications on erosion processes experienced in the last decade a slow but steady increase. In Germany the percentage of publications related to the subject increased by 65% between 2000 and 2005, with a total number of 213 publications in the year 2004. The worldwide average of increase in the same period is about 40%.

The greatest density of scientific publications per population can be found in New Zealand (4,3 million inhabitants), with 73 publications per 1 million inhabitants, a second group is formed by Norway (4,8), Swiss (7,7), Australia (21,9) and Denmark (5,5), followed finally by a third group comprising the United Kingdom ,Canada, Sweden, Belgium and the Netherlands.

Fig.3. Publication per population, this index is a value for efficiency of the scientific process (after MITTERMAIER et al. 2007).


Ressources:

MITTERMAIER, B.; PLOTT, C.; TUNGER, D.; BURKARD, U. & LEXIS, H. (2007): WissdeX Erosion. (Access 24.06.2010)
Bibliometrie - Trenderkennung in der Wissenschaft (Access 24.06.2010)

New and past volcanic islands in the Mediterranean Sea

Researches of the INGV (Istituto Nazionale di Geofisica e Vulcanologia) and the University of Calabria have announced that a previously unknown volcanic mountain was detected in the Tyrrhenian Sea, 120m below sea level off the coast of Calabria in the area surrounding Capo Vaticano (38° 50' N; 15° 50' E).
The results of the aeromagnetic and geological survey will be published in the upcoming Journal of Geophysical Research (JGR). The researchers followed a "trackway" of ancient volcanic deposits of unknown origin in the area of Capo Vaticano, finally extending their search with a geomagnetic survey into the sea. The radiometric dating of the pumice on land also gives an approximate phase of activity for the new unnamed volcano of 670.000 to 1 million years ago.
The volcano is situated on a tectonic fault zone, and is thought to represent an extension to the east of the volcanic arc of the Aeolian Islands, an interesting observation that maybe will have important influence on the understanding of the general configuration of plate margins in the Tyrrhenian Sea.

The presence of submarine volcanoes is not unusual in the surroundings of Italy and especially Sicily. In the canal of Sicily, between the Italian island and the African coast, a number of volcanic mountain ranges are know, thought to be the remains of an increased volcanic activity one million years ago. The island of Pantelleria for example is only one of the most prominent and highest peaks in the region. In July 1831 a secondary volcanic aperture of the main volcanic complex of "Empedocles" (named after the Greek naturalist) erupted and reached sea level, forming a cone up to 60m high. The property of the new formed island soon became a dispute between France, who named it Julia, England, who named it Graham, and Sicily, who named it Ferdinandea (the introducing figure depicts an artistic rendering of the 1831 eruption). The controversy got resolved after 5 months, when the island was completely eroded by the action of the waves. Today the peak of the island lays 6m below sea level, after an increased tectonic activity between 1980 and 2000 raised it by 2m.
The weak, but ongoing volcanic activity of Ferdinandea in 1987 fooled even the crew of an American vessel, misinterpreting the rumours caused by the volcano for a hostile submarine; they decided to bomb it...

References:

VENÈ, M (2003): La Miniatlantide Siciliana. In: Vulcani d´Italia. Supplemento allegato al N. 262 di Airone Febbraio 2003

On the tracks of ancient reptiles

In March 2010 the discovery of a new site with fossil footprints from the Triassic in the province of Trentino was announced, adding an ulterior chapter to the rich geological and paleontological history of the pale mountains - the Dolomites.
These rich fossil deposits, the geology and the significance for the development of geological sciences of this area were reasons to insert the Dolomites in June 2009 in the list of World Heritage sites.

The first recognition of fossil traces of vertebrates dates back to 1800-1802, when a young student discovered dinosaur footprints in the Jurassic sediments of Connecticut.
But ichnology, the study of fossil tracks, was not establishes as independent science until 1950. Considering this, the Dolomites have played an important role in the history and development of ichnology.

In 1891, in a sandstone quarry near the villages of Glen and Montan, Province of Bolzano, the amateur naturalist F. Gasser picked up a strange piece of rock. He sent the presumed fossils to the Austrian palaeontologist Ernst Kittel, who recognizing similarities between the imprints on the rock with the footprints of a reptile (Chirotherium) discovered in 1833 in Triassic sediments (Buntsandstein) of Thuringia. Kittel in the same year published a brief account of the discovery in the journal of the Austrian Tourist Club - the first report of fossil tracks found in South Tyrol.

The notice (and translation) of the discovery of the reptilian trackway as published in the journal of the 'Österrischen Tourist Clubs "in 1891:

“Saurierfährte von Bozen: Aus der Umgebung von Bozen kennt man schon seit einiger Zeit Sandsteine, welche den Porphyr überlagern, und welche in gewissen Lagen ganz ähnliche Erscheinungen zeigen, wie die Buntsandsteine von Hessberg in Thüringen, nämlich auf den Schichtflächen erscheinen "Rippelmarken" (durch Wellenschlag oder Wind erzeugte wellenförmige Furchen), ausgefüllte netzförmige Trockenrisse und Fährten unbekannter Saurier, die man Chirotherium und Saurichnites nennt. Wenn nun auch diese Erscheinungen aus der Gegend von Bozen angeführt werden, so gelangen solche Stücke doch sehr selten in die Museen, was gerade nicht für ihre Häufigkeit spricht. Im naturhistorischen Hofmuseum befinden sich z.B. nur Trockenrisse von Saltern, dann Rippelmarks von eben demselben Orte, die ziemlich undeutlich sind. Eine unzweifelhafte "Saurierfährte" aus einem Steinbruch am Westgehänge des Mte. Cislon etwa zwischen Gleno und Montan nächst Neumarkt bei Bozen hat Herr Dr. F. Gasser in Atzenbrugg an die Section eingesendet. Dieselbe ist freilich nicht so gut erhalten, wie die Stücke von Hessberg, jedoch immerhin ist der erhabene Abdruck einer gefingerten Tatze erkennbar. Es wäre nur zu wünschen, dass uns etwas mehr von diesen Funden zukäme, damit genauere Vergleiche mit besser bekannten anderen Saurierfährten ermöglicht würden.
Die Fundstelle am Hessberg gehört bekanntlich zum "Buntsandstein", dagegen rechnet man die Bozner Sandsteine zum "Grödener Sandstein", welcher für älter als Buntsandstein gehalten wird und daher meist für "oberpermisch" gilt. Weitere Mittheilungen derartiger Funde sind sehr erbeten.”

"Reptile tracks of Bozen: In the vicinity of Bozen there are known sandstones, which are superimposed on the porphyry, and which in certain layers show properties that are very similar to the ones of the red sandstone of the Hess Mountains in Thuringia, so there appear on the layer surfaces "ripple marks" (wave-like furrows generated by water or wind), reticulate cracks and tracks of unknown reptiles, called Chirotherium and Saurichnites.
Even if these peculiarities are known from the area of Bozen, examples of these features are very rare in the museums, which speak not for their frequent discovery.
In the natural history museum for example are known only mud-cracks of the area of Saltern, and then indistinct ripple marks from the very same place.
An unquestionable "reptilian track" was send to the section by Dr. F. Gasser from Atzenbrugg, it comes from a quarry on the western flank of Mount Cislon, approximately between Gleno and Montan, in the vicinity of Neumarkt, near Bolzano. The same is certainly not as good as the specimens of the Hess Mountains, but after all a fingered paw is recognizable. I only wish that some more of these findings are send to us, it would allow more accurate comparisons with other better-known reptilian tracks.
The site in the Hess Mountains, as it is well known, belongs to the "Buntsandstein", but the sandstones of Bozen are included in the "Grödener Sandstone", which is considered to be older then the “Buntsandstein” and attributed to the "Upper Permian".
Other communications of such finds are much appreciated."

Only years later, in the summer of 1931, Gualtiero Adami, an engineer and employee of the Natural History Museum of the former Province of Venezia Tridentina, discovered during an excursion near the village of Piné a rock on which, at is seemed, was engraved a figure similar to a lizard.
The fossil was consigned into the custody of local museum and later studied by the geologist Giorgio del Piaz. During a meeting of the Italian Society for the Advancement of Science in September of that year he announced the preliminary study and the "discovery of a new genus, likely a paleolacertide, collected near Piné and found in a thin bed of tuff, interbedded within the Permian porphyry”.
The fossil also confirmed the hypothesis that reptiles were the authors of the footprints found in the same or overlying formations. The fossil, however, after these announcements was not studied further and put aside, first treasured in Milan, then in 1938 brought to Padua. In 1942 the palaeontologist Giambattista Dal Piaz briefly mentions the finding, referring to it as "a beautiful lizard-like reptile, certainly from a terrestrial habitat.”
The fossil finally was (and still is) exposed in the museum of the Geological Institute of Padua with the denomination “Tridentinosaurus antiquus by GB Piaz”, but only in 1959 the specimen is described scientifically by the palaeontologist Piero Leonardi, who recognizes it’s significance, as a vertebrate in peculiar preservation condition (skeletal remains surrounded by a carbonaceous patina of soft parts) and the oldest body fossil of the Southern Alps. It’s suggested by some authors, based on the preservation of the fossil, that the animal was killed during a volcanic eruption by a pyroclastic surge.

Fig.2. Tridentinosaurus.

For further signs of reptilian activity in the geological past of the Dolomites, we have to wait until 1946, when the geologist Piero Leonardi begins to study the Permian flora of the Val Gardena sandstone, formation with important fossil bearing sites known since 1877.
Intrigued by an account of the fossil flora of the Bletterbach canyon near the villages of Aldein and Radein, he contacts the author, the engineer Leo Perwanger. Together during field excavations they find more fossils, and some plates with the trackways of reptiles. After some supplementary field season in 1951 Leonardi publish the results, and realizes the importance of the site.

He continues the research and is joined by the palaeontologist and expert for fossil trackways Accordi and his students. Leonardi in the summer of 1951 discovers an ulterior site, on the flank of Mount Seceda in the Val Gardena, where a large succession of Permian yellow to red sandstones is outcropping. Yet other sites were discovered in 1955, along the road between Pause and Doladizza on the left side of the Etsch-Valley, and the following year near the pass of San Pellegrino.

Fig.3. Tetrapod tracks and skin impressions (right below). Strati di Werfen - Formation, Triassic - Passo Palade.

Research in the gorge of Bletterbach is continuing from 1973 until today. The creek on the bottom of the gorge has carved into the side of the mountain a large geological scar, offering the possibility to observe and cross the entire upper Permian and lower Triassic sedimentary succession. From here comes one the most comprehensive footprints collection of Permian terrestrial reptiles, with so far 9 ichnospecies comprising 8 ichnogenera, some of them attributed to Synapsids, which makes this site even more exceptional.

Fig.4. Visit to the gorge of the Bletterbach (BZ).

References:

AVANZINI, M. & WACHTLER, M. (1999): Dolomiti La storia di una scoperta. Athesia S.a.r.l. Bolzano: 150
AVANZINI, M. & TOMASINI, R. (2004): Giornate di Paleontologia 2004 Bolzano 21-23 Maggio 2004 Guida all´escursione: la gola del Bletternach. Studi Trentini di Scienze Naturali - Acta Geologica Supplemento al v.79 (2002):1-34
LEONARDI, G. (2008): Vertebrate ichnology in Italy. Studi Trent. Sci. Nat., Acta Geol., 83 (2008): 213-221

Investigating the Taphonomy of Volcanic eruptions: How volcanoes kill

The first scientists and journalist arrived on the island on May 21., on board of the American vessel “Dixie”, researchers from the United Kingdom and France soon followed.

13 days before the city of Saint-Pierre had been destroyed by a volcanic eruption. The geologist were baffled by the extant and pattern of the destruction - the eruption killed 30.000 people and destroyed the entire city - but despite the damage and eyewitnesses reports no signs of a lava flow were discovered.
The amount of destruction decreased gradually or suddenly, tand he geologist Edmund Hovey of the American Museum of Natural history claimed: "In many places the limit passes on single trees, letting one side dark and burned, the other green as if an eruption never happened."
Then, on the 9th of July, the English geologists Tempest Anderson and John S. Flett of the Royal Society of London became eyewitnesses of the true phenomenon that destroyed the city:

“The cloud had a spherical form and resembled rounded protuberances amplifying and doubling with terrifying energy. They extended to the sea, in our direction, boiling and changing shape in every moment. It didn’t spread laterally. It didn’t rise up in the atmosphere, but it descended on the sea in a turbulent mass interspersed by thunderbolts”

For the first time geologists observed a deadly “nueé ardente” as later the phenomenon was called by the French volcanologist Alfred Lacroix (1863-1948), or pyroclastic flow. According to later observations of molten glass (melt temperature 700°C) and unaltered copper tubes (melt temperature) found in the ruins of the city the temperature of the pyroclastic flow was estimated to 700-1.000°C.
The deathly factor of a volcanic eruption differs considerable with the kind of eruption and the distance to it. The most dangerous eruption are surely of explosive or phreatomagmatic nature. Pyroclastic density currents, turbulent hot mixtures of fine ash and gas flowing down volcano slopes at high speeds, are common in volcanic explosive eruptions. They can devastate large areas and cause numerous fatalities by exposure to mechanical impact, extreme heat and dusty gas.
To understand how exactly these phenomena act and how far their deathly effects reach is essential to plan and improve risk mitigation management.
A research published by MASTROLORENZO et al. 2010 address these questions using one of the most popular cases of a deadly eruption associated with pyroclastic event: the eruption of Mount Vesuvius in the year 79 A.D, that destroyed the villages and cities surrounding the volcano, the greater one being Pompeii.

Fig.1. Simplified stratigraphy of the vulcanic deposits in Pompeii correlated to the chronology of the destruction of the cities surrounding Mount Vesuvius. The 79 AD Vesuvius eruption generated a sequence of six distinctive pyroclastic surges (S1 to S6) and flows with increasing power, which caused widespread building collapse and fatalities.
The pyroclastic surge S4 caused most of the fatalities in Pompeii, even if the resulting deposit are only 3 centimetres thick, because it was the first surge to actually reach and cover the city, devastating an area of ca. 80 km2.

The first human remains were discovered in Pompeii only two months after the beginning of systematic excavations, on 19. April 1748 at the crossing of Via Stabia and Via Nola. During the more or less scientific motivated excavation campaigns in the following centuries further human and animal remains were discovered, in Herculaneum (destroyed by an Lahar) 328 bodies, in Pompeii the known bodies until 2002 are 1.150, not considering some hundred bodies discovered during the centuries, but later buried for reverence or lost.
Hester Lynch, visiting Pompeii in 1786 remembers: "some people would take away some parts, as I did to possess in my little museum a bone older then 17 centuries; .[].. as I observed a French gentleman, when I saw him put a human bone in his pocket.”

Fig.2. Discovery of human remains during the visit of the emperor Giuseppe II in Pompeii, Jean-Claude Ricard de Saint-Non (1781-1786) (image from DE CAROLIS & PATRICELLI 2003).

The new research compared artificially heated recent bones with bones recovered from the surge deposits of Pompeii. Also the documented position of bodies in relation to the stratigraphy of ash and surge deposits was considered.
In Pompeii, within the lapilli bed were found 394 skeletons of victims of the early fallout eruptive phase, 90% of whom died within buildings probably due to roof and floor collapse. Deposits of the later S4 surge preserved the remains of 650 victims heretofore supposed to have died by ash suffocation. From these 93 plaster casts, in addition to 37 corpses from Oplontis (a seaside suburbia site) and 78 skeletons of Herculaneum, were classified in a scheme considering the posture of the corpse, for example life-like when showing an apparent "freezing" in the act of movement - most bodies were found in such a posture (73%).

The damage on the ancient bones, showing micro-cracks on the surface and recrystallistaion of the interior structure, are signs of thermal modification. Comparing these bones with the observations made on modern bones, heated in experiments, the researchers were able to determinate a temperature range inside the surge that killed the people, at least 500-600°C at Oplonis and Herculaneum, and 300-250°C at Pompeii.

The temperature at Herculaneum and Oplontis was enough to vaporize the flesh of the victims, so that the ash could embed the skeletons, where in Pompeii the bodies remained intact inside the volcanic sediments. After decaying of the organic material a void remains, that today can be grouted with plaster to form a cast.

The published result questions some earlier assumptions, like the supposed main death cause of the people by ash suffocation. The new study indicate that heat was the main cause of death, the exposure to the at least 250°C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death and spasm ("freezing" the people’s movement), even if people were sheltered within buildings.
Despite the fact that impact force and exposure time to dusty gas of the pyroclastic flow declined toward the periphery of the surge, theoretically improving survival possibilities, lethal temperatures were maintained up to the extreme depositional limits of the flow.

References:

DE CAROLIS, E. & PATRICELLI, G. (2003): Vesuvio 79 d.C. la distruzione di Pompei ed Ercolano. L´ERMA di BRETSCHNEIDER: 129
GIACOMELLI, L.; PERROTTA, A.; SCANDONE, R. & SCARPATI, C. (2003): The eruption of Vesuvius of 79 AD and its impact on human environment in Pompeii Episodes. Vol. 26, No. 3
LEWIS, T.A.(ed) (1985): Volcano (Planet Earth). Time-Life Books: 176
LUONGO, G.; PERROTTA, A. & SCARPATI, C. (2003): Impact of the AD 79 explosive eruption on Pompeii, I. Relations amongst the depositional mechanisms of the pyroclastic products, the framework of the buildings and the associated destructive events. Journal of Volcanology and Geothermal Research 126: 201-223 doi:10.1016/S0377-0273(03)00146-X
LUONGO, G.; PERROTTA, A.; SCARPATI, C.; DE CAROLIS, E.; PATRICELLI, G.; CIARALLO, A. (2003): Impact of the AD 79 explosive eruption on Pompeii, II. Causes of death of the inhabitants inferred by stratigraphic analysis and areal distribution of the human casualties. Journal of Volcanology and Geothermal Research 126: 169-200 doi:10.1016/S0377-0273(03)00147-1
MASTROLORENZO, G.; PETRONE, P.; PAPPALARDO, L. & GUARINO, F.M. (2010): Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii. PLoS ONE 5(6): e11127. doi:10.1371/journal.pone.0011127

Cartoons and Earth Sciences: Mammals nibbling off dinosaurs

"Beware to the teachings of those, whose ideas are not confirmed by experience."
Leonardo da Vinci (1452-1519)

Caricatures and cartoons can bring science and scientific discussion to the attention of a broader public, they also can transport messages, direct critic to a topic or unintentionally predict future discoveries...

Fig.1. A cartoon by Dr. Robert Bakker (1986) lampooning the assumption that dinosaurs were cold-blooded animals and during cold periods were easy prey for mammals.
"Mesozoic nightmare: being a cold-blooded dinosaur during the rainy season. If big dinosaurs really were mass homeotherms, then the rainy season would have sapped their body heat and left them torpid and vulnerable to the warm-blooded mammals."

This cartoon, drawn by the palaeontologist Dr. Robert Bakker, is criticising the image of dinosaurs predominant some decades ago. Dinosaurs, especially the giant sauropods, were generally assumed as cold-blooded , very lazy animals. Mammals were depicted as furry, insignificant and even superfluous animals during the Mesozoic, and considering the media coverage in some quarters it's seems still so...

But let's consider, not to seriously, the relationships of gnawing mammals and dinosaurs.
There are more than 100 theories to explain the extinction of the vast majority of dinosaurs. Between the more improbable suggested hypothesis we find that mammals feed on dinosaur eggs (which does not explain the extinction of marine reptiles, pterosaurs, ammonites and other molluscs etc...) and caused an extinction by eliminating the unborn generations. After this idea, the mammals, after million of years of coexistence, decided that time was come for revenge, and devoured as many eggs as they possible can to drive dinosaurs to a slow, but inevitable extinction.

The hypothesis that mammals fed on (some) dinosaur eggs is plausible, but so far we lack the fossil evidence, unlike the evidence that mammals preyed (small) dinosaurs and, after the release of a new research, gnaw on dinosaur bones. In 2005 the giant Mesozoic mammal Repenomamus robustus , a mammal up to 1 meter long, was described, and found with an accumulation of little dinosaur bones within his chest.

Now a research of bones excavated from Canadian cretaceous sediments revealed little gnaw-imprints on bones of dinosaurs, aquatic reptiles and marsupials.
Nicholas Longrich of the Yale University and Michael J. Ryan of the Cleveland Museum of Natural History interpret these bite marks as gnawing on bones by probable representative of the Multituberculata, to assimilate the mineral components of the bones.

Fig.2. The marks identified as probable signs of a mammals gnawing the bones, from MUZZIN 2010.

And even if I am pro-mammal, to argue after these findings that dinosaurs were eaten by mammals is still very hypothetical...

Ressources:

BAKKER, R.T. (1986): the Dinosaur Heresies - New Theories Unlocking the Mystey of the Dinosaurs and Their Extinction. William Morrow and Co., New York: 481
MUZZIN, S.T. (2010): Dinosaur-chewing mammals leave behind oldest known tooth marks. Online 16.06.2010, visited 17.06.2010

The Tauern WIndow, inside the treasure chest of the Alps

It seems that my little excursion in the geological history of the Tauern Window pleased my readership - so thank you and as special gift let's continue our exploration:

The Tauern Windown has been studied by geologists since the mid 19th century, and research is still ongoing.
The first geological maps of the region is the "Geognostische Karte von Tirol" of 1849, that differs three lithological units in this area, the "mica schists group (Gruppe des Glimmerschiefers)", comprising various schist's with mica, hornblende, chlorite and carbonate components, the group of the "clay mica schists (Gruppe des Thonglimmerschiefers), massive to schistous limestone, diorite and serpentinite" and single Serpentinite bodies.

Fig.1. Geognostische Karte von Tirol, 1849, figure from here. The Tauern Window is the rosé area in the right upper part.

Fig.2. Oblique 3D view of the transition between Centralgneiss and cover units (Bündner Schiefer) to the surrounding basement crystalline (Altkristallin / Austro-alpine nappes), modified after: Carta Geologica d´Italia (1967): Foglio Nr. 1 + 4a "Passo del Brennero e Bressanone" 1:100.000.

In 1851 the Swiss geologist STUDER in his book "Geology of the Swiss" compares the calcareous phyllites in the area of the Brenner Pass with the phyllites of the Swiss cantons of Bündens and Wallis, and notes that the Centralgneiss descends under these series. In 1853 the geologist of the Geological Survey of Austria, LIPOLD, STUR and PETERS describe the various lithological units and confirm that the schists are overlying the gneiss, and the unit shows a general dip away from the centre of the Tauern Window.
They propose a general subdivision in Centralgneiss (Zentralgneiss), the Schists cover (Schieferhülle, comprising the old roof -Altes Dach- the Palaeozoic sedimentary cover and the permomesozoic Bündner Schists with intercalated ophiolites) and the old or basement crystalline (Altkristallin).
STUR considers the Gneiss as a Triassic intrusion, mangled between and in the overlying units during the Eocene "a mechanic force of incredible impact... which was able to disrupt the precedent less affected order..., to overthrow the youngest on the oldest."

Fig.3. Fine grained mica-granite on the left intruding in a Biotite-Plagioclase gneiss. The gneiss has been partially melted and melt residuals concentrated in the white patches. In the melt large Plagioclase crystals growth (rectangular white shapes). In a last phase open fissures caused by exhumation of the Centralgneiss and resulting brittle deformation were filled with a pegmatite.

Between 1871 to 1872 NIEDZWIEDYKI studies and publishes the results of his survey of "Theilen der Zillerthaler Alpen und der Tauern", where he confirms the stratigraphic succession, and interpret it as continues sedimentation with no tectonic implications (It's interesting to observe how interpretations of same regions can differ such considerably).

In 1872 STACHE subdivides the schist cover in two groups, and considers the gneiss as the base formation of the Alps. In the following years the lithological and stratigraphic relationships get elaborated in more detail, the schist cover is subdivided in a carbonate poor and carbonate rich part, and the "Matreier Zone" is introduced, a melange between the basement crystalline and the Schist cover.

Fig.4. Schist with hornlende, so called Hornblendengarbenschiefer of the Greiner Serie, part of the "Old Roof".

Until the beginning of the 20th century the observed metamorphic sediment units were considered autochthone, and so there was no significant progresses (or need) regarding tectonics to explain the succession of such different units.
Then, in 1903 TERMIER applies the theory of tectonic nappes, first developed in the Swiss Alps, to the Eastern Alps, and explains the Tauern geology as a result of a tectonic window, formed by erosion of the upper nappes, and displaying the lower nappes of the Alps.

In the classic Austrian geology since then the nappes of the Eastern Alps were subdivided in the lowest Penninic nappe (with the Tauern window as most prominent example) and overlying East Alpine nappes, with a lower, median and upper nappe comprising various units (in case of the Tauern window the surrounding crystalline basement).
This classification was simplified in the last years. Not only is a strict subdivision not always possible, also it is more likely that the single nappes of the East Alpine don't represent a succession of deposition environments in different geological periods (as assumed in the past) but simple different facies in a spatial continuum of the former paleozoic Ocean, subsequentely stacked together bz the Alpine orogenesis. Today a more general term - "Austroalpine Deckeneinheiten", Austro-alpine Nappe Units, is preferred.

Fig.5. Rich in Minerals are the hidden fissures...During the Alpine orogenesis and metamorphosis of the great varieties of rocks that compose the cover of the Tauern Window, circulating fluids deposited a rich variety of minerals in the fissures that opened during exhumation - Quartz, Plagioclase, Rutile , Amphibole and Gold depending from the surrounding source rocks.

References:

LAMMERER, B. (1975): Geologische Wanderungen in den westlichen Zillertaler Alpen. Alpenvereins-Jahrbuch 1975 Bd. 100: 13-25
ROST, H. (1989): Zur Geologie, Petrographie und Tektonik des Pennins, der Matreier Zone und des Altkristallins zwischen Pürschbach und Grossklausenbach (Durreck-Gruppe, Ahrntal, Südtirol). Unveröffentlichte Diplomarbeit am institut für Geologie und Mineralogie Friedrich-Alexander-Universität Erlangen-Nürnberg: 192 S.

The history of alpine tectonics and a visit to the Tauern window

Soon after the systematic geological mapping of the Alps and with the establishment of a stratigraphic column between 1830 to 1880 geologists get interested how mountain ranges form. The first geological studies of sedimentary successions in France and United Kingdom required only vertical movements to be explained, movements thought to result by igneous intrusions in the underground (idea proposed by Hutton) or by the contraction of a cooling earth. The German geologist von Buch related the growth of mountains and folding to igneous bodies, intruding and displacing older sediments. In contrasts the French geologist Elie de Beaumont developed a theory involving a periodic contraction of earth, resulting in volcanoes and earthquakes and tectonic movements. The periodicity of these movements were based on his observations of different tilted sediment layers, formations, deposition and presumed erosion phases.

Fig.1. De Beaumont’s two classes of sedimentary deposits, constraining the age of sudden upheaval pulses of mountain ranges: (1) previously horizontal beds (b), tilted up and contorted on flanks of rising core (a), and younger flat beds (c) extending up to the foot of the chain;(2) in this case, also beds (c) are disturbed and flanked by new horizontal deposits (d) (from DalPIAZ 2001).

The hypothesis of Beaumont becomes quickly accepted by the majority of European and American geologist, besides being in contradiction of the slow processes invoked by Lyells gradualism. With the introduction of the concepts of nappes and mountain fold-belts in geology by the observations of various geologists during the late 19th century, like the Austrian geologists Eduard Suess and Otto Ampferer, the picture become more complicated, tangential movements of earth crust seemed necessarily to explain these features.

Until them contorted relationships of different formations were interpreted as results of folding, Marcel Bertrand, a young French geologist that never worked in the Alps, reinterpreted in 1884 completely one of the classic profiles of the Glarus double fold drawn by the Swiss geologist Heim.

Fig.2a. Section with the "double fold" through part of the Glarus Alps, by Albert Heim, from Livret- Guide Géologique, 1894, figure from FRANKS & TRÜMPY 2005.

Fig.2b. The Glarus overthrust as depicted in a watercolour by the geologist H.C. Escher in 1812 (figure from PFIFFNER 2009). The thrust forms the contact between older (Helvetic) Permo-Triassic rock layers of the dark Verrucano (Permian - Triassic sandstones and conglomerates) group and younger (external) Jurassic and Cretaceous white limestones and Paleogene flysch and molasse.

Bertrand replaced the double fold by a single nappe, laterally displaced over 40km - but his paper was widely ignored. Suess after an excursion to the Glarus Alps in 1892 was inclined to Bertrand idea, but even he failed to persuade the dominant geological establishment. With the works of the Swiss Geologist Hans Schardt in 1893 and 1898, where he demonstrated that some prominent mountains of the external Swiss Alsp represents the eroded remains of much larger cover nappes, the existence of nappes, not after great aversions, become accepted. Pierre Termier in 1904 extended the nappe structure to the Eastern Alps and developed the concept of tectonic windows.

Fig.3. The geologist Argand adopted between 1909 and 1934 the idea of nappes in the geology of the Alps, here a generalized view of the Europe-vergent Alpine belt. Note that the Eastern Alps (4) override the western Alpine nappe stack (2-3), and its root zone is indented and back-folded by the Southalpine hinterland, in turn deformed by south-vergent thrust. The Western Alps consist of ophiolite-bearing cover sequences (3) and Penninic nappes (2), squeezed out from the contraction of Alpine geosyncline (I-III: Simplon-Ticino nappes;IV-V-VI: Gran St. Bernard-Monte Rosa-Dent Blanche nappes), and overthrown onto the sliced (a-b: Helvetic basement) and undeformed (c) European foreland (1) (from DalPIAZ 2001).

To the east of the Brenner Pass the south-western branches of the Zillertal Alps reach the South Tyrolean realm. Here a sudden and exceptional lithological change can be observed, crystalline schist's lay in contact with a succession of marbles (Fig.5. and 6.) and metamorphic sandstones and breccias, followed by green calc-schists and serpentinites (Fig.4.) and amphibolites, and finally a vast area of gneiss, a rock that is more resistant to erosion and forms a characteristic landscape with prominent peaks.

Fig.4. Prasinite and calc-schist boulder (geologic map) of the "Bündner Schiefer".

Fig.5. Dolomitic marbles (Jurassic) of the Tristenspitze (geologic map) "sitting" on thrusted gneiss.

Fig.6. Dolomitic marbles (Jurassic) of the Tristenspitze.

This varied succession contrasts strongly with the surrounding monotone schist's, and aroused the interest of generations of geologists.
The schist represents former Ordovician to Devonian marine sediments.
The metamorphic sediments (marbles and metamorph clastic formations) were interpreted as lithologies of an early Permomesozoic and a later Mesozoic ocean (Penninic Ocean), becoming in the Cainozoic sandwiched between the two collision fronts of the European continent and various plate fragments of the Adriatic realm.
The central gneiss, denominated appropriately "Zentralgneis" or Tauern gneiss, comprises a large number of metamorphic rocks, mainly of granitic origin intruded 250 million years ago in the Permomesozoic sediments, and is part of the European basement.

Fig.7. The Tauern gneiss (Central gneiss) in the background surrounded by tectonized and eroded gneiss in the foreground. From the central gneiss it is possible to traverse the ocean floor magmatites, then sediments, to arrive in the tectonic overthrusted older metamorphic and monotone schists of the Austroalpine units.

During the Alpidic orogenesis the sediments were overthrusted by the Austroalpine units, which constitute the frame around the window today.
Thus, the window allows insight into the Penninic units, the deepest tectonic units of the Eastern Alps. This extraordinary situation designated the Tauern window as a key of understanding the Alpine nappe stack since early times of research.
The exhumation of the Tauern window occurred mainly in the Oligocene and Miocene, tectonic units east of the window were pushed further to the east, a phenomenon designated as lateral extrusion.

A sign of ongoing tectonic activity are earthquakes, which occur predominantly on the western boarder (Brenner Pass and Wipp- and Eisacktal, following the fault zone of the Periadriatic lineament), the northern boarder (Inntal thrust zone), and in minor entities and magnitude on the southern limit (Defreggen-Antholz-Pustertal thrust zone).
A new published research (PLAN et al. 2010), carried out in a cave in Styria, dated earthquake-damaged speleothems and scratched flowstone to as recent as the last glacial maximum, between 118ka an 9ka, suggesting that the Salzachtal-Ennstal-Mariazell-Puchberg (SEMP) fault, a major strike-slip system in the European Alps developing from the Inntal fault north of the Tauern Window, is still active, and lateral extrusion of Alpine units on a large scale in direction of the Pannonian Basin are still ongoing.

References:

DalPIAZ, G.V. (2001): History of tectonic interpretations of the Alps. Journal of Geodynamics 32: 99-114
FRANKS, S. & TRÜMPY, R. (2005): The Sixth International Geological Congress: Zürich, 1894. Episodes, Vol. 28(3): 187 - 192
PLAN, L.; GRASEMANN, B.; SPÖTL, C.; DECKER, K.; BOCH, R. & KRAMERS, J. (2010): Neotectonic extrusion of the Eastern Alps: Constraints from U/Th dating of tectonically damaged speleothems. Geology v.38(6): 483-486.
PFIFFNER, O.A. (2009).Geologie der Alpen.Haupt Verlag Bern-Stuttgart-Wien: 359