The fossil forests of Amethyst Mountain

The fossil forests of Specimen Ridge and Amethyst Mountain, both situated in the Yellowstone National Park, are peculiar because of many preserved trees still found as upright trunks and stumps emerging from the sediments.
The geologist, anthropologist and artist Dr. William H. Holmes was the first to study the outcrop of Amethyst Mountain and published his observations in 1878:

"As we ride up the trail that meanders the smooth river bottom [the Lamar River] we have but to turn our attention to the cliffs on the right hand to discover a multitude of the bleached trunks of the ancient forests. In the steeper middle portion of the mountain face, rows of upright trunks stand out on the ledges like the columns of a ruined temple. On the more gentle slopes farther down, but where it is still too steep to support vegetation, save a few pines, the petrified trunks fairly cover the surface, and were at first supposed by us to be shattered remains of a recent forest."

Fig.1. Pencil drawing ca. 1879 by Holmes of the outcrop of Amethyst Mountain, National Archives.

Fig.2. Two fine specimens of fossil tree trunks of Pilyoxylon aldersoni in the fossil forest on a steep hillside of Specimen Ridge, exposed by erosion of the basic breccia in which the stumps and roots are firmly embedded. Nearby a hoodoo, showing the character of the breccia and the manner in which it has been deposited. Circa 1890. Figure 2, U.S. Geological Survey Folio 30, USGS Photo Library.

Holmes studying the outcrops realized that the silicified stumps are distributed in various levels (more than fifty are today recognized) and embedded in volcanic deposits like ash, mud flows and breccias. These deposits provided also an explanation of the remarkable well preserved structure of the wood: from the rocks the silica was solved by the percolating water and substituted the organic matter of the wood. Inside of some hollows trunks even geods with crystals of amethyst formed and the name of the mineral was adopted previous of 1870 to the entire site, unfortunately most of these specimens were removed by collectors already in the late 19th century.
The upright position and the well preserved roots are a sign that the trees became embedded in situ, covered by ashes, mudstone, breccias and conglomerates during a volcanic eruption. There are also signs of fluvial reworking of the deposits, many trees rooted in tuffaceous sandstones, interpretated as paleosoils, and conglomerates deposited by a braided river system.

Fig.3. Schematic profile of Amethyst Mountain as imagined by Holmes and published in "Fossil forests of the volcanic tertiary formations of the Yellowstone National Park. Bull U.S. Geological and Geographical Survey of the Territories Vol.5.(1), 1879-1880"

A modern example possibly resembling the environment of formation of the petrified Yellowstone forests was the landscape after the eruption of Mount St. Helens in 1980. Here a violent eruption razed down large areas of the forest surrounding the mountain, leaving behind stumps that were buried under pyroclastic flows and lahars.
Today, more than 30 years later the effects of the explosion are still visible, even if a new forest has begun to colonize the devastated area. Subsequent research showed that St. Helens experienced many eruptions in the Holocene, repeatedly the area was devastated and repeatedly the area was reconquered by nature.

Also in Yellowstone the buried forest was destroyed, entombed in the volcanic deposits and the new formed landscape colonized again by a new forest. The time period involved in these cycles was however at the time of Holmes unclear, however the perfectly preserved tree rings inspired geologists to try to estimate how much time was involved in the growth phase of the plants and finally in the formation of the entire sedimentary succession:

"Pine trees of the types represented in the fossil trunks require 200 or 300 years to reach maturity, and redwoods may require from 500 to 1,000 years. Twelve or more of these forest levels have been found. By multiplying this number by the minimum age of the trees (200 years) we shall have 2,400 years, and by multiplying it by the maximum age of the redwood (1,000 years) we shall have 12,000 years as the possible time during which these forests flourished. It is possible that the truth lies somewhere between these extremes."
(KNOWLTON 1921)

Glacial erosion on Specimen Ridge and Amethyst Mountain showed that the volcanic activity was older than the ice age and therefore geologist inferred a tertiary age, so Knowlton in 1921 summarizes:

"After the Cretaceous period, there was a time of great volcanic activity, which appears to have lasted until perhaps the beginning of the glacial epoch."

Today the sediments are dated thanks to modern methods into the Eocene. The events at St. Helens provided also a possible time period for the formation of the fossils, well preserved wood was found in centuries old lahars of the volcano with silica beginning to substitute the organic matter, in some cases even after 36.000 years the fossilisation was not completed.

However I have to note that this scenario is only a theory and there is an alternative explanation: the forest was buried in a worldwide flood send by a magic, invisible creature living in the sky that so loved its own creation that it decided to destroy it to punish a single species of upright, naked ape, with the exception of a single family dedicated to inbreed - much more plausible than a series of boring volcanic eruptions...

Online Ressource:

COFFIN, H.G. (1976): Orientation of trees in the Yellowstone Petrified Forests. Journal of Paleontology. Vol.50(3): 539-543. (Accessed 16.05.2011)
KNOWLTON, F.H. (1921): Fossil Forests of the Yellowstone National Park. USGS Monograph 32: 651-791. (Accessed 16.05.2011)
VINEY, M. (2008): The Virtual Petrified Wood Museum. (Accessed 16.05.2011)

Old Man River

Caricature published in the newspaper "Ledger" 03.05.1927 depicting the "Old Man River" affected by a severe case of "floods".
The Secretary of Commerce Herbert Hoover and the Commander of the Engineer Corps Major General Edgar Jadwin of the US-Army endorse the common (snake oil ?-)cure: higher and higher dams as projected for the Mississippi River and Tributaries Project after the great flood of 1927 - despite modern methods like reforestation, flood management and limitation of construction in flood plains, dismissed as new-fashion drugs, are available.

Cabinets of curiosities #5: The Last of Their Kind

"Begin at the beginning and go on till you come to the end; then stop."
Lewis Carroll (1832-1898)

Presumably 99% of all the species that inhabited earth in the geological past went extinct, some during mass extinctions, most however slowly but inescapable, even if some described creatures or monsters and fossils apparently never existed.
A strange flightless bird became an icon of extinction - endemic on Mauritius today only fragments survive in our museums and as cruel aftermath his appearance became soon distorted by humans after his extinction.
The role of human induced extinction during the Pleistocene is still discussed - for example for the strange marsupial lion, for the recent past however it is well documented, especially for species confined on archipelagos or islands like in the Arctic or Japan or Tasmania.
But also species with billions of individuals were hunted down so efficiently that they went extinct in a geological blip.
Today at least we care and try to minimize the impact of our society on the environment and species richness; however it is clear that it is necessary to assign priorities, not only for animal, but also plant species.

A geologist riddle #16

This drawing will be related to a next week anniversary, the most peculiar feature of this outcrop are the small vertical structures as seen in the left sketch - so what phenomena and concept of geology is recognizable here ?

Earthquakes and the rapture

Peter Hadfield debunks again all the religious crap and quacks misusing geologic phenomena to promote their delusions:

Fig.1. Boxplot-diagram showing earthquake magnitude after Richter in the years 1900-2002 - the mean value of every year shows no significant trend 1900-1960, since 1960 the monitoring system incorporates more and weaker earthquakes, therefore the step - but again the mean value of all events per year show no trend, also stronger earthquakes do not surpass the years of the first half of the 20th century…all the self-proclaimed prophets obviously didn´t even bother to control the information aviable on the site of the U.S.G.S.

And now more prophets....

War Geology

In the year 1915 the Great War reached the, at the time, Austrian Dolomites as the neutral Italy declared war to the Austrian-Hungarian Empire. The military high commando feared that bypassing the Alps the Italian army could reach the city of Vienna in just one week, so it was decided to secure the most important routes and mountain passes at the national borders.

The Falzarego pass, connecting the city of Cortina d´Ampezzo with the western valleys, was of strategic significance - this pass is situated at 2.105m a.s.l. and is dominated in the north by the nearly vertical cliff of the small Lagazuoi, a 2.700m high mountain.

Fig.1. The Lagazuoi overlooking the Falzarego pass situated at the left corner of the photography. The Austrian front line followed the crest of the mountain.

There was no experience with war in such an extreme and alpine environment, it was nearly impossible to attack directly the enemy when he hid behind inaccessible rocks or in steep cliffs and soon a position warfare between the Austrian and Italian troops developed.
The strategists of the military tried to resolve this problem with a war technology successfully adopted in the soft shale, cretaceous sediments and quaternary deposits of the low plains of France, Netherlands or Russia: the mine war. Long tunnels were dig until approaching hidden in the underground the enemy front line, then the end of the tunnel is filled with explosives or mines and the enemy simply blasted away.
In mountains by undermining the enemy position or by causing rock-fall on the enemy it was possible to misuse the geology as tactical weapon of mass destruction. However the Triassic rocks of the Dolomites were much harder to excavate than expected and only with great effort in material and men it was possible to extend the military tunnels by 10m every day in the dolostone.

In the years 1915 to 1917, when the war in the Dolomites was finally abandoned, at the entire front line of Tyrol 34 blasting operations were attempted, 20 by the Italian army and the remaining by the Austrian army.
The Austrian army realized the importance to know the geology of the battle fiels and instituted a special division formed by war-geologists - the "Kriegsgeologen". These geologists recorded the geology in the front line and studied the best solutions for engineering problems to construct defensive positions, artificial tunnels and other military infrastructures. Apart their military duties they however enjoyed great liberties and were allowed to move free at the front line and to continue their scientific work by collecting samples, rocks and fossils. Also in the Italian army many professional geologists were engaged, even if the Italians never possessed an own military geologists-division.

Fig.2. A romantic view of the war in the Dolomites as seen by the Austrian artist and alpinist Gustav Jahn (1879-1919), who fought in the first world war. Soon the soldiers realized that this war would last much longer than expected and that the beautiful landscape hid a harsh mountain environment that would cost more lifes than the battle operations.

The Lagazuoi is composed of the Cassian Dolomite-formation, dolostone of a former Triassic reef complex with the massif reef core at its centre and the clinostratification of reef debris interfingering with marls of a sea basin to the east. The dolostone of this formation is hard but brittle and also tectonically weakened, so driving small tunnels into the mountain is still possible, even if a tedious quest.
In 1915, to reach the Italian position situated in middle of the southern rock wall of the Lagazuoi, the Austrian army begun to excavate from the northern slope a tunnel trough the mountain. Adopting a similar strategy the Italian soldiers tried to undermine the peak of the Lagazuoi, where the Austrian soldiers were stationed, so the Italian excavated in five months a more than 1.000m long tunnel to reach a position below the mountain peak.

The Austrian Kaiserjäger Hanz Berger remembers the work in the tunnels:

"In the tunnels I'm afraid to be blasted into the air from below or to become entrapped, the pointers of my clock seem to slow down in this place, a second lasts for two, a minute for 20 minutes, a night can last forever and it seems that the sun is gone forever."

Fig.3. The Austrian front line follows a rock wall on the summit of the Lagazoui - today the huts and the tunnels used by the soldiers are a memorial place.

Fig.4. A simple hut constructed by the soldiers.

Fig.5. Inside the hut, the soldiers lived for months, often the entire winter, in such primitive shelters.

Fig.6. View outside one of the tunnels through a loophole into the valley.

At the Lagazuoi many tunnels were constructed and 5 mines were detonated by the two armies during the war:

Shortly after midnight of the new-year day of 1916 the Austrian army initiated the mine wars at the Dolomites front with the detonation of 300kg of explosives inside of the Lagazoui. A large boulder was blasted off but it caused only minor damage on the huts of the Italian position.

On 11.07.1916 the Italian army blasts off the "Castelletto", a rock ledge on the steep cliff of the Tofana di Roces, a mountain situated in the east to the Lagazuoi, using 35.000kg of explosives hidden in a 400m long gallery inside the mountain. They hope to bury and destroy the underlying Austrian front line, 13 soldiers were killed.

Fig.7. The Tofane di Roces today.

On 14.01.1917 using 16.000kg of explosives a 37m in diameter and 45 deep crater was blasted into the mountain, still today the debris of the explosion is recognizable at the base of the cliff of the Lagazuoi (left debris cone).

22.05.1917 the third Austrian blast operation with 30.400kg explosives tries to destroy the Italian position, 200.000 cubic meters debris fell off from the mountain producing a 200 high and 140m broad scar, 4 Italian soldiers were killed.

In the morning of the 20, June 1917, after the construction of a complex gallery trough the mountain, 33.000kg of explosives deposited under the peak of the Lagazuoi explode, tearing apart the mountain and producing the right debris cone at the base of the Lagazuoi.

Fig.8. The scar in the rock wall and the debris cone produced from the explosion in 1917 is still well visible. The Italian front line was situated in the middle of the rock wall, on the large step visible in the photography, formed by the contact of two stages of the reef-growth during the Triassic.

The Italian soldier Luigi Panicalli recalls this day:

"I realize that in few moments the results of all this months, in which we worked and suffered, will be shown. I'm like petrified. In this last moments my thoughts are by the enemy - poor guys - do they feel that death is approaching, do they anticipate that their enemy is inside the mountain and will hurl them from the summit of the mountain into the grave ?"

In the end the various attempts and operations in all these years didn't change the front line or the progress of the war - and still today the scars of the mountain are visible like silent reminders of the madness of war.



Bibliography:

AVANZINI, M. & ZAMBOTTO, P. (2009): Paleontologi in Guerra. PaleoItalia 20: 17-20
PIERO, G.; AVANZINI, M.; BREDA, A.; KUSTATSCHER, E.; PRETO, N.; ROGHI, G.; FURIN, S.; MASSARI, F. PICOTTI, V. & STEFANI, M. (2010): Dolomites 7th international Triassic Field Workshop Pan-European correlation of the Triassic. Field trip to the world heritage site of the Tethyan Triassic September 5-10, 2010 Dolomites, Southern Alps, Italy: 122

Online Resources:

KNOPP, G. (2009): Der Kampf um Südtirol. (Accessed 11.05.2011)
STRIFFLER, R. (): Die 34 Minensprengungen an der Tiroler Gebirgsfront 1916-1918. (Accessed 11.05.2011)

A geologist riddle #15

There is a tragic connection between the following contrasting photographs, it will give you the location and the connection to geology of what happened here: