Maria Matilda Ogilvie Gordon - A Women Geoscientist In The Dolomites

The Scottish Maria Matilda Ogilvie Gordon (1864-1939), or May as she was called, was the oldest daughter of a pastoral family composed of eight children, five boys and three girls. Maria Ogilvie entered Merchant Company Schools' Ladies College in Edinburgh at the age of nine. Already in these early years, she showed a profound interest in nature. During holidays she enjoyed exploring the landscape of the Scottish Highlands accompanied by her elder brother, the later geologist Sir Francis Ogilvie. Maria Ogilvie aspired to become a musician and at age of eighteen she went to London to study music, becoming a promising pianist, but already in the first year her interests into the natural world prevailed and she went 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 a recommendation even by the famous geologist Baron Ferdinand Freiherr von Richthofen (pioneer geologist of the Dolomites), she was rejected at the University of Berlin - women were still not permitted to enroll for higher education in England and Germany. She went to Munich, where she was welcomed friendly by eminent paleontologist Karl von Zittel (1839-1904) and zoologist Richard von Hertwig (1850-1927). However, she was not allowed to join male students. Sitting in a separate room she listened through the half-open doors to the lectures.

In July 1891, Richthofen invited her to join a five-week trip to the nearby Dolomites Mountains, visiting the Gröden-Valley. From the very first day, Maria Ogilvie was immensely impressed by the landscape and learned rock climbing to better explore the mountains. Richthofen introduced Maria Ogilvie to alpine geology and they visited the pastures of Stuores in the Gader-Valley. At the time Maria Ogilvie was studying modern corals to become a zoologist, but Richthofen, showing her the beautifully preserved fossil corals found here in the Triassic sediments, convinced her to become rather a geologist.

The pastures of Stuores in the Gader-Valley with outcrops of Triassic marl.

Richthofen was over sixty years old and therefore he couldn't provide much support in the field. Maria Ogilvie remembers later the challenge and danger of field work, sometimes accompanied by a local rock climber named Josef Kostner:

"When I began my fieldwork, 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."

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 "Contributions to the geology of the Wengen and St. Cassian Strata in southern Tyrol". In the paper she included detailed figures of the landscape, geological maps and stratigraphic charts of the Dolomites, establishing fossil marker horizons and describing the ecology of various fossil corals associations. She described 345 species from the today 1,400 known species of mollusks and corals of the local Wengen- and St. Cassian-Formations.
The published paper, a summary of her thesis "The geology of the Wengen and Saint Cassian Strata in southern Tyrol", finally earned her respect by the scientific community. In 1893 she became the first female doctor of science in the United Kingdom. The same year she returned into the Dolomites to continue with her geological and paleontological research. In 1894 she published the important "Coral in the Dolomites of South Tyrol." Maria Ogilvie argued that the systematic classification of corals must be based on microscopic examination and characteristics, not as usually done at the time, on superficial similarities.

Fossil corals from the pastures of Stuores, plate from LAUBE (1865).

In 1895 she returned to Aberdeen, where she married a longstanding admirer. Dr. John Gordon respected and encouraged her passion for the Dolomites. He and their four children accompanied Maria Ogilvie on various excursions into the Dolomites.

In 1900 she returned to Munich, becoming the first woman to obtain a Ph.D. She helped her old mentor, paleontologist von Zittel, to translate his extensive German research on the "Geschichte der Geologie und Palaeontologie" - "The History of Geology and Palaeontology."

Maria Ogilvie continued her studies and continued to publish. In 1913 she was preparing another 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.
In 1922 she returned into the Dolomites, where she encountered the young paleontologist Julius Pia, who, during the war, had carried out research in the Dolomites. Together they explored many times the Dolomites.

Landscape profile of the Langkofel-massif after GORDON & PIA (1939): Zur Geologie der Langkofelgruppe in den Südtiroler Dolomiten. Maria Matilda included hand-drawn sketches in her research.

Apart from scientific papers, Maria Matilda published also one of the first examples of geological guide books for the Dolomites. To honor her contributions to earth sciences in 2000 a new fossil fern genus, discovered in Triassic sediments, was named Gordonopteris lorigae.

Interested in reading more? Try:

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

Permian Pyroclastic Flow Facies

The German geologist Christian Leopold Freiherr von Buch (1774-1853) was one of the most known geologists of the first half of the 19th century. Educated as a Neptunist, he became quickly interested in volcanoes and their deposits and therefore decided to visit the nearest active volcanoes. So in 1800 he travelled by feet from Germany to Italy, taking with him only one dress, a note book, a barometer and his hammer.
He was the first to study in detail the outcrops of reddish rocks surrounding the South Tyrolean city of Bozen and recognized them as volcanic products and named them appropriately: Bozner Quarzporphyr - quartz porphyry of Bozen.

Fig.1. Example of typical "Bozner Quarzporphyr", this term encompassed very different volcanic facies, like ignimbrite rich in feldspar crystals and flattened clasts (in the photo) deposits, lava flows and even clastic fluvial sediments, only in the last decades a more specific approach and distinction was adopted.

This complex reaches an incredible maximal thickness of 4.000 meters The precise age, origin and geotectonic significance of the Permian magmatism in the Southern Alps is still controversial, one (classic) model propose that the intense volcanism was triggered by the extension of the lithosphere during the break-up of the supercontinent of Pangaea, a second model interprets the volcanic rocks as the magmatic arc of a nearby (today not preserved anymore) subduction zone. Early interpretations suggested that the Bozner Quarzporphyr is mainly a homogenous infill of a gigantic volcanic caldera.
However the Athesian Volcanic Group (the modern term) is a complex succession of both plutonic, magmatic and sedimentary rocks, it consists of volcanic episodes with pyroclastic density currents, ash- and tuff-layers, lava flows, clastic and limnic sediments of erosion phases during volcanic resting phases and intrusion of plutonic rocks, that became uncovered by tectonic movements and erosion.

Fig.2. Geological map of the eastern part of the Athesian Volcanic Group with supposed borders (stripped line) of former caldera, after BARGOSSI et al. 2004.

Fig.3. Example of intruded plutonic rock in the volcanic rocks of the Athesian Volcanic Group, feldspar-porphyry of the Terlano sub-volcanic body.

Many of the various volcanic rocks were and still are used in construction and especially as paving stone.
The Nalles-Formation consists of a sequence of events which produced an aesthetic volcanic breccia. This tuff-breccia is organized in very thick parallel beds, made by variable portion of volcanic, angular to poorly rounded, large clasts swimming in a matrix of crystal fragments and ashes. Some of the larger fragments show a coloured rim as results of thermic alteration. This facies was obviously deposited still quite hot, in a high energy regime capable to transport at the same moment fine particles but also large boulders - this suggest that these are deposits of repeated pyroclastic flows (which even maybe killed at least one poor reptile).

Fig.4. Nalles-formation with large clasts swimming in a matrix of crystal fragments and ashes.

Fig.5. Detail of larger clasts with thermic reaction rim.

Bibliography:

MORELLI, C.; BARGOSSI, G.M.; MAIR, V.; MAROCCHI, M. & MORETTI, A. (2007): The lower Permian volcanics along the Etsch Valley from Meran to Auer (Bozen). Mitt. Österr. Minera. Ges. 153: 1-25

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)

12 April, 2010: The railway debris flow of South Tyrol

12. April 2010 South Tyrol: 9 confirmed victims, 23 people injured; this was the headline about a rail crash between the towns of Latsch and Kastelbell reported by the news almost worldwide.
The modern railway between the two localities follows the orographic right bank of the main river Etsch, the accident occurred at a segment inside a gorge eroded by the river in Holocene sediments (manly a large alluvial fan coming from south with unconsolidated debris-flow deposits).
At 9.02 in the morning, just when the train approached, a debris flow of 400 cubic meters - with a width of 10 to 15 meters and a thickness of 2m - bursted off 50m above the railway line and hit the first wagon, knocking it from the railway.

Fig.1. The derailed train during the difficult rescue efforts (SüdtirolNews).

To clarify possible causes of the landslide soon after geological investigations were initiated. Eye witnesses reported large quantities of water running down the slope after the accident. A preliminary site investigation by the authorities concluded that the leakage of an irrigation system above the location (the area is used for agriculture) saturated the soil and underlying sediments with water, causing a mudslide just in the moment the train passed. The irrigation system was in use since the previous week and at least for the last days or hour's large quantities of water infiltrated in the underlying slope and saturated the debris. It is possible that the vibrations of the approaching train triggered finally the fatal slide that initiated the debris flow.

Today, one year after the deadly debris flow, a memorial stone was inaugurated to remember the nine victims of the disaster.

The Iceman story

"I remembered the effect that the view of the tremendous and ever-moving glacier had produced upon my mind when I first saw it. It had then filled me with a sublime ecstasy that gave wings to the soul, and allowed it to soar from the obscure world to light and joy. The sight of the awful and majestic in nature had indeed always the effect of solemnising my mind, and causing me to forget the passing cares of life. I determined to go without a guide, for I was well acquainted with the path, and the presence of another would destroy the solitary grandeur of the scene."

Mary W. Shelley "Frankenstein" (1813)

It was a fast and lonesome death, wounded by an arrow in the back, the man bleed to death within minutes. The body was left on the site of the murder, maybe the aggressors assumed that scavengers and time would erase all of the evidences, but in the cold and dry climate the body begun to desiccate and large scavengers didn't venture in this desolate realm, only some flies were able to deposits their eggs on the body but they weren't able to destroy it.
During the next winter snow accumulated in the gully where the body laid and in the next decades and centuries the snow transformed slowly into ice, protecting and preserving the mortal remains.

Fig.1. The small snowfield on the middle of this photography is covering again the gully in which the body of "Ötzi" was discovered.

Time passed, then in the late summer of 1991 - exact 20 years ago- two German tourists, Helmut and Erika Simon, accidentally discovered the body emerging from the ice, the marked ablation during the summer (helped by sunny weather and the deposition of Saharan dust on the glacier ice, that absorbed much solar radiation) of the small glacier near the Similaun Hut, in the Ötztaler Tyrolean Alps, brought the corpse back to the surface.
The prehistoric mummified corpse - soon known worldwide as "Ötzi" the Iceman - together with its unique set of artefacts, provided a unique opportunity for the research of the cultural development of a bronze-age culture, this corpse is the highest prehistoric find (ca. 3.280m a.s.l.) in the Alps.

But the body and artefacts provided also insights on the glacier dimensions during the little known phases of the warmest parts of the Holocene in Europe. This phase is practically undocumented by glacial sediments, eroded by later glacial advances, and is only recognizable by proxy data like changes in pollen diagrams or dating organic materials, over- or underlying glacial or proglacial deposits.

During the last glacial maximum some 18.000 years ago the entire area was completely ice-covered, only narrow and steep arêtes and horns protruded from the ice. In the area of the Similaun Hut sharp trim lines in a height varying from 3.060m to 3.400m divide the uppermost frost-shattered crests from the lower slopes, smoothed by glacial erosion. The trim line can also recognized locally as marked weathering line that separates different oxidized surfaces (the bed rock consists of Fe-rich gneiss and schist).
A second trim line is marked by an abrupt change in lichen diameter (from 100mm above to 40mm below) and density. The dating by lichenometry attributes this glaciers to the Little Ice Age (LIA, ca. 1.600-1.850), which generally corresponds to the maximum Holocene glacier expansion.
The mummy itself was dated by radiocarbon dating to 4.500+-30 and 4.580+-30 yr B.P., which corresponds to a calibrated age of 5.300-5.050 yr B.P. The relatively sudden burial of the corpse in a more or less permanent snow and ice cover indicates a significant climatic change that induced glacier expansion at the beginning of the Neoglaciation in the second half of the Holocene.
This supposed change of the glaciers was supported also by some soil horizons found in depression between 3.000 and 3.215m a.s.l. and dated to 5.615+-55 yr B.P. (6.450-6.300 cal yr B.P.) and 3.885+-60 yr B.P. (4.416-4.158 cal yr B.P.). Similar recent soils needed at least 5 to 12 centuries for its development, suggesting that the climatic conditions on the site were for a long time relative favourable for biological and chemical activity.

The Iceman and his site so reveal that between 9.000 and 5.000 yr B.P. the mountain glaciers were smaller than in the second half of the Holocene. About 6.400 cal yr B.P. and for several centuries after, an ice-free peripheral belt allowed the accumulation of organic matter and developments of relatively thick soils. Between 5.300 to 5.050 cal yr B.P. ago a rapid climatic change took place, producing a persistent snow cover and the expansion of glaciers, which conserved the body until again the glaciers begun to retreat.
And the recent retreat of the glaciers still continues, in 1970 the glacier that revealed the mummy was part of the much greater Niederjoch Glacier, a composite alpine glacier that descends northward in the Nieder-Valley, but only in the last 5 years the Niederjoch-glacier lost 60-100m length.

Fig.2. The "Similaun" as highest peak (3.597m a.s.l.) with his two main glaciers, the "Similaun" in foreground, and the "Niederjoch" in background. Until ca. 1970 the glaciers flowed together, but the glacier retreat in the last years was notable.

Fig.3. Location (black circle) of the site of the bronze-age mummy in the Ötztaler Alps. Blue areas represents the glacier extends in 2003, the red line the glacier extends during the Little Ice Age (ca. 1600-1850), blue, green and yellow the main glacier-stages during the Pleistocene-Holocene transition.

The environment in which the Iceman lived was characterised by a rich biodiversity, he could use and in fact used an astonishing variety of plants found in his living space.
Both the axe shaft and the long bow were found in the vicinity of the corpse and were made of yew (Taxus baccata), a resistant and elastic wood typ. The quiver for the arrows was made of caprine skin and was stiffened with the elastic wood of the hazel tree (Corylus avellana). The 14 arrows were made of the hard wood of the wayfaring tree (Viburnum lantana). One is repaired, the front end being restored with dogwood (Cornus). The dagger handle is also made by hard wood from a piece of ash (Fraxinus excelsior). Its sheath was knotted from the bark of basswood (Tilia). He carried also two containers made of birch (Betula) bark, in one were found charcoal pieces wrapped in Norway maple (Acer platanoides) leaves.
Several wood species could be identified from the charcoal remains, probably spruce (Picea/Larix-type), pine (Pinus mugo-type), green alder (Alnus viridis), some Pomoideae which were probably Juneberry (cf. Amelanchier ovalis), dwarf willow (Salix reticulata-type) and elm (Ulmus).
A sort of backpack was constructed from a thick branch of hazel (Corylus avellana) bent into a U-shape, together with two coarsely-worked laths of larch (Larix decidua).

The majority of wood species found with the Iceman grow in the montane regions (valley bottoms to 1.800 m), although some subalpine (1.800-2.500 m) and alpine (above 2.500 m) conifer species are also represented. Their ecological requirements point to the transition zone between thermophilic mixed-oak forest communities (Quercetalia pubescenti-petreae) and the montane spruce forest (Piceetum montanum). Norwegian maple (A. platanoides), European yew (T. baccata), ash (Fraxinus sp.), lime (Tilia sp.) and elm (Ulmus sp.) allow to infer a humid habitat with a mineral rich, free-draining soil and a mild winter climate.
All that is similar to the present-day conditions in the woodlands found on the slopes and in gorges in the lower Schnalstal and Vinschgau in South Tyrol, where it is assumed he lived.

So the botanical evidence seems to confirm a climate comparable to modern conditions, and implies a glacial extent similar, if not slightly minor to the present. This has very important influence on the reconstruction of past, and modern climatic and glacial development, and at last the actual discussion about climatic change.

Bibliography:

BARONI, C. & OROMBELLI, G. (1996): Short paper - the alpine "Iceman" and Holocene Climatic Change. Quaternary Research 46: 78-83
MAGNY, M. & HAAS, J.N. (2004): Rapid Communication - A major widespread climatic change around 5300 cal. yr BP at the time of the Alpine Iceman. Journal of Quaternary Science 19(5): 423-430
OEGGL, K. (2009): The significance of the Tyrolean Iceman for the archaeobotany of Central Europe. Veget. Hist. Archaeobot. 18:1-11

AW#31 - Talus Thoughts

Jim Lehane on The Geology P.A.G.E. is asking the question "What geological concept or idea did you hear about that you had no notion of before (and likely surprised you in some way)."

Well I will admit that there is a problem that I come across only in geologically recent times and still puzzles me.

"Beautiful is what we see,
More beautiful is what we understand,
Most beautiful is what we do not comprehend."
Nicolaus Steno, 1673

Can a pile of rubble have e name and be studied? Apparently yes - a Talus (term used in North America, borrowed from the architecture of fortresses)) or Scree (English) can be defined as landform composed of rock debris accumulated by mass-wasting processes - or as pile of rubble. But despite this simple explanation, their humble origin, being often neglected during lectures or considered only disturbing in mapping the bedrock lithology, talus slopes are complex geomorphologic features still holding many secrets (not only to me).
These landforms occur in a wide range of environments, but most predominantly where the climate enforces on steep rock walls or cliffs physical weathering and mass-wasting. If the supplied rubble is enough, the subsequent weathering and removal rate low, a characteristic, thick cone or slope of rock debris can form. Rockfall is one important factor to form a talus; however depending on the catchment are other mass-wasting processes can act on the morphology of the talus, large rock avalanches can occur, debris flows, avalanches and dry grain flows also transport material on the developing slope.
These various processes can alter the form, the composition and the grain size found on the talus - so it is not easy (if possible) to foresee the inner matrix by only observing the surface. In most cases the coarse openwork surface texture is merely a veneer. Talus deposits consist of debris with a wide range of sizes, like a sieve, fine material accumulates in the voids in the deeper parts of the talus. Interestingly for me such a similar phenomenon has been observed also in rock glaciers and landslide deposits - I therefore experienced that is it tricky to map such features as simple aquifers.


Fig.1 and 2. More regular Talus slope / Talus aprons in the upper photo and cataclinal (bedding and slope coincide) slope with various Talus cones and modification by debris flows in the Dolomites.

Fig.3. Example of talus deposits reworked by debris flows (with the typical levees on the sides of the channel) in the Central Alps, area characterized by schists and metasediments. Physical and chemical erosion in such rocks is generally stronger, talus deposits tend therefore to be fine grained and covered by soil and vegetation.
Talus deposits are mainly results of mass-wasting processes, if fluvial ("wet") processes play also or a dominant role the term Talus fans is used.

The overall morphology of a talus slope depends also on the form of the cliffs supplying the debris. Straight plain cliffs will produce a straight sheet talus (Talus slope / Talus aprons), cliffs with channels or gorges will canalize the debris and Talus cones will form. It is mostly that both forms will occur in narrow spatial and temporal succession, a regular cliff will develop channels with ongoing erosion and faults can disrupt the regular conformation of a cliff.
Many talus slope profiles show at least segments with an inclination of 33-35°, a common value for rubble, however considering the entire slope there are significant variations. Mapped talus slopes show that the upper part has an angle of 32-37°, up to 40°, the medial part approaches the value of 33°, the lower part displays low angles and a basal concavity. The segmentation of the profile is in accordance to a change in the facies.
This shape is explained in part by various processes acting along the profile, in the upper part transport and deposition of debris, in the lower part mainly deposition. There is also a change in the grain size caused by "fall sorting": large boulders with their large momentum and energy proceed until the toe of the slope, also the roughness increases downhill, where older large boulders can stop the run of the new arriving boulder. The degree of sorting depends on the slope length, cliff height and the size and shape of dominant particles. This is an important effect of talus slope to be considered when defying a zone of danger or planning mitigation efforts.

Talus slopes in periglacial environments are again peculiar in some characteristics. A snow patch on the base of the slope and subsequent sliding of debris above this surface can produce a distinct ridge, termed protalus rampart or nivation ridge. Covering of snow by such debris is thought to produce an ice-rock mixture that can begin to creep following gravitational pull, a protalus lobe (often unfortunately also referred as protalus rampart), considered by me as one possible variation of rock glaciers.
When the ice melts out, unlike glaciers these lobes can not recede and became fossilised.

Fig.4. Complex talus deposits in the Antersac-Valley, Dolomites. The basal vegetation covered protalus rampart is a relict of a colder climate in a periglacial environment, probably during the aftermath of the last glacial period (18.000-12.000 years ago). Rockfall from the steep cliffs and canalized by a gully provide further debris, forming a talus cone, however the vegetation cover shows that the activity on it today is low. Most recent modifications are erosion of the upper part and secondary mobilization of material by various debris flows.

The coarse debris forming the talus can become preserved, and there is ongoing research to use these deposits to interfere the climate of the past. The presence of a Talus as such is not specific related to climate or environment, however the processes (avalanches, debris flows, grain flows) forming or modifying the Talus are depending on the climate.
Another possibility, despite recognizing the characteristic forms of ice-rock bearing talus slopes, is to try to calculate the accumulation of debris, and so the rate of weathering of the cliff. Assuming that a cold and wet climate increases debris production the ages of talus deposits can provide ages of such climatic phases. In talus slopes composed of carbonate rocks it is also possible to date directly the cement or the matrix formed between large boulders. Measuring the oxygen or carbon isotopes it is possible to recover direct climatic values.


These are only some considerations of many. Talus slopes are wonderful complex landforms, and being common in the region I work, they still continue to fascinate and intrigue me.

Bibliography:

LUCKMAN, B.H. (2006): Talus Slopes. In (ed): ELIAS, SA: Encyclopedia of quaternary science. Elsevier: 2242-2248

Ichnofacies associations of the Bletterbach section

I already introduced the fossil site of the Bletterbach gorge, recognized by geologists for the first time in 1951. However after some preliminary studies and some recuperated fossil imprints a systematic research began only in 1973, resulting in the discovery of a large number of tracks and trackways.

These discoveries were followed by a systematic stratigraphic and paleoenvironmental reconstruction of the site, and led to the revision of its chronological attribution (from the Middle to the Late Permian, 260-251 Ma) and its ichnological content. Recognized the significance of the Bletterbach gorge, research continued and the site became some years ago a geology park with marked itineraries for visits and local documentation centres. In June 2009 it was inserted as "Geotop" along the Dolomites in the list of World Heritage sites of the UNESCO.

The Bletterbach gorge is one of only five major outcrops of tracksites worldwide dated to the Late Permian and from these possesses the most diverse assemblage of ichnofossils.
The facies association occurs in sandstones deposited in the alluvial plain and channels of a river system that regularly flooded the former semi-desertic landscape. The ichnofauna assemblage is extraordinary rich with 9 ichnospecies belonging to 8 ichnogenera.
The presumed terrestrial track makers range from gigantic pareiasaurs, medium-sized to large herbivorous anapsid reptiles, small and relatively primitive diapsids and to large synapsids. In some cases, the foot-prints are exceptionally well preserved, showing details of the skin and imprints of the single claws.
Pelycosaurs, one of the dominant reptilian groups during the Permian, are present by the imprints of large caseids, reaching an estimated length of 2 meters. An important peculiarity of the site is the discovery of tracks attributed to gorgonopsians, the only known example of imprints of this group recorded in central Europe. Other therapsida imprints, only 5cm small and with the classic 4 to 5 forward facing digits, were left probably by cynodonts.

Fig.1. Pachypes dolomiticus (LEONARDI et al. 1975), amongst the largest Paleozoic tetrapod footprints found in the Bletterbach, has been referred to pareiasaurs by means of comparison with the skeletal features of several Palaeozoic reptilian groups (digits show upward).

Fig.2. Morphofamily Chiroteriidae (ABEL, 1935) - imprint of a large archosaur and the oldest known examples of this kind of tracks (digits show to the right).

Fig.3. Rhynchosauroides in the foreground - three distinct ichnospecies are recognized in the Bletterbach of this track, all of them attributed to small, lizard-like creatures (lepidosauromorpha).

Fig.4. Imprint of a large synapsid (gorgonopsia?) with five digits, even the marks of the claws are recognizable.

Fig.5. The mid-nineteenth century fanciful view of the trackmakers: a labyrinthodont amphibian (centre) leaves a Chirotherium trackway watched by dicynodonts (left) and rhynchosaurs (right).
(B.W. Hawkins archive,The NaturalHistory Museum, London), found in BOWDEN et al. 2010

Fig.6. A more realistic reconstruction - Tetrapod Footprints from Bletterbach and causer: a) Pachypes dolomiticus; b) Rhynchosauroides pallini; c) Ichniotherium accordii; d) Dycinodotipus isp.; e) Chirotheriidae (From PIERO et al. 2010).

Bibliography:

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
BOWDEN, A.J.; TRESISE, G.R. & SIMKISS, W. (2010): Chirotherium, the Liverpool footprint hunters and their interpretation of the Middle Trias environment. In: MOODY, R. T. J., BUFFETAUT, E., NAISH, D. & MARTILL, D. M. (eds) Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications, 343, 209 - 228
LEONARDI, G. (2008): Vertebrate ichnology in Italy. Studi Trent. Sci. Nat., Acta Geol., 83 (2008): 213-221
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
VALENTINI, M.; CONTI, M.A. & NICOSIA, U. (2008): Linking tetrapod tracks to the biodynamics, paleobiogeography, and paleobiology of their trackmakers: Pachypes dolomiticus Leonardi et al., 1975, a case study. Studi Trent. Sci. Nat., Acta Geol., 83: 237-246

The discovery of the ruins of ice

"It has already been said, that no small part of the present work refers to the nature and phenomena of glaciers. It may be well, therefore, before proceeding to details, to explain a little the state of our present knowledge respecting these great ice-masses, which are objects of a kind to interest even those who know them only from description, whilst those who have actually witnessed their wonderfully striking and grand characteristics can hardly need an inducement to enter into some inquiry respecting their nature and origin."

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

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

Today worldwide glaciers were studied and monitored as climate proxies, and the recent measurements show that almost all of them are retreating fast. The story about glaciers, their influence on the landscape and their possible use to reconstruct and monitor climate is an intriguing one, with many triumphs, setbacks and changes of mind.

For centuries, if not even millennia, the high altitude belt of mountain ranges were a region visited and travelled by man, however also haunted and forbidding places. The glaciers, masses of ice enclosing peaks and extending their tongues into valleys, were considered the residence of mountain spirits, then during the medieval times the prison of damned souls (the Italian poet Dante Alighieri 1265-1321 imagined the centre of hell as a frozen wasteland) and the playground of demons, who from time to time send avalanches and debris flows into the valley.
Despite these myths there was some early insights of what glaciers actually really are made, the Greek historian and geographer Strabo (63 - 23) describes a voyages trough the Alps during the reign of Augustus and mentions

"…there is no protection against the large quantities of snow falling, and that form the most superficial layers of a glacier…[]. It's a common knowledge that a glacier is composed by many different layers lying horizontally, as the snow when falling and accumulating becomes hard and crystallises...[]."

However the knowledge got lost, and was only rediscovered during the Renaissance. Leonardo da Vinci´s (1452-1519) is considered one of the greatest Renaissance-geniuses, he studied anatomy, biology and geology, however regarding the glaciers of the Alps his ideas were somehow confused, the thought glaciers were formed by not melted hail accumulating through the summer. But soon the study of nature experiences an incredible raise, and glaciers find place in various descriptions of travelling scholars.

Between 1538 and 1548 glaciers were labelled (even if not depicted) with the term "Gletscher" on topographic maps of Switzerland. In his account on the Swiss land the Theologian Josias Simler in 1574 describes the Rhone-glacier.
The first historic depiction of a glacier is considered the watercolour-paint of the Vernagtferner in the Ötztaler Alps from 1601. The Vernagtferner was a glacier that repeatedly dammed up the Rofen-lake (named after the Rofen-valley), which outbursts caused heavy damage and loss of property, particularly in the years 1600, 1678, 1680, 1773, 1845, 1847 and 1848.
In 1642 the Swiss editor Matthaeus Merian the Older in his "Topographie Helvetiae, Rhaetiae et Valesiae" published various copper engravings of glaciers, and in 1706 Johann Heinrich Hottinger is interested to explain the motion of "the mountains of ice" in his "Descriptio Montium Glacialium Helveticorum."
Johann Jakob Scheuchzer, visiting in the year 1705 the Rhône Glacier, published his observations of the "true nature of the springs of the river Rhône" in the opus "Itinera per Helvetiae alpinas regiones facta annis 1702-1711", and confirms the idea that glaciers are formed by the accumulation of snow and they move and flow.

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

The increasing interest to study glaciers in the Alps is also encouraged by enthusiastic travel reports; in his "Voyage pittoresque aux glaciers" the A.C. Bordier of 1773 describes the Bosson glacier as a "huge marble ruins of a devastated city".
The naturalist Horace Benedict de Saussure (1740-1799) is fascinated by the mountains of his homeland, he climbed mountains around Geneva since 1758, and after 1760 he travelled more than 14 times trough the Alps (considering the possibilities in this time an extraordinary achievement). Between 1767 to 1779 the first volume of his "Voyages dans les Alpes" is published, were he reassumes his observations and theories about the visited glaciers, he recognized moraines and large boulders as the debris accumulated by the glacier tongue and proposes to map them to interfere the former extent of glaciers. Despite this exact statement, de Saussure failed to connect large boulders found in the foreland of the mountains to the glaciers of the Alps. He assumed that these rocks were transported on their recent locations by an immense flood. That seemed to explain why most of the boulders found scattered around the plains of Germany came in first place from the regions of Scandinavia, where the same lithology where found in the crystalline continental basement, like Precambrian metamorphic rocks and Paleozoic sediments. The theory worked lesser to explain the foreland Alpine rocks - to transport boulders from the Alps the flood at least had to reach 1000 of meters.
The idea of a flood as the explanation for "glacial" deposits became largely accepted, it seemed to fit the description of the biblical flood; even Lyell and Darwin assumed that huge erratic boulders were transported by swimming ice drafts on top of a flood wave.
That glaciers could propagate far out of their valleys was however not an unusual idea for local inhabitants, who observed and experienced the growth and recess of glaciers. In academic circle this approach was a little more difficult.
A contest thought to demonstrate the former extension of Swiss glaciers initiated by the Swiss pastor Jakob Samuel Wyttenbach in 1781 (maybe inspired be the advance of the Alpine glacier in 1770) didn't arise any interest.

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

There were only careful speculations considering a former expansion of glacier: the geologists James Hutton (1726-1797) and his friend John Playfair (1748-1819) speculated about glaciations of the northern hemisphere. In 1826 a publication by the Danish mineralogist and mountain climber Jens Esmark (1763-1839) was translated into English, in this paper Jesmark discussed the possibilities that glaciers where much greater in the past then today. J.D. Forbes and Robert Jameson (who were the geology professors of Charles Darwin at Edinburgh University, Darwin in his autobiography of 1876 remembers "The sole effect they produced on me was the determination never as long as I lived to read a book on Geology or in any way to study the science.") discussed glacial theories during their lectures. And even Buckland, who still in 1831 argued "northern region of the earth seems to have undergone successive changes from heat to cold", in 1837 was converted to Lyell's uniformatism and considered that sudden changes, like an ice age and glacier expansion, simply don't happen in geology.

In 1815 Jean Pierre Perraudin, a chamois hunter in the Val de Bagnes, told to the engineer Ignatz Venetz his theory that the glaciers once covered the entire valley, and Venetz mapped features that made him even recognize that once the entire Swiss was covered by ice. Vernetz´s lecture on the assembly of the Swiss association for natural history in 1829 found little interest, only Jean de Charpentier, director of the salt mine in the city of Bex (Western Swiss), who 14 years earlier had meet and discussed with Perraudin, this time accepted and got interested in this theory.
He begun a detailed mapping project, and in 1834 Charpentier presented again before the Swiss association the results of his investigations, but the flood theory had still much supporter. One of the critics in the public was a former student of Charpentier, named Jean Louis Rodolphe Agassiz, respected palaeontologist by the establishment. Charpentier invited Agassiz to visit the city of Bex and surrounding mountains, and to observe glaciers.
In the following year (1837) Agassiz held an enthusiastic lecture about glaciers, ice ages and ice shields, and in 1840 published a detailed study of modern glaciers, their deposits and their spurs in his "Etudes sur les glaciers."
Agassiz experienced the same scepticism as many other ice-age proponents before.

"I think that you should concentrate your moral and also your pecuniary strength upon this beautiful work on fossil fishes .... In accepting considerable sums from England, you have, so to speak, contracted obligations to be met only by completing a work which will be at once a monument to your own glory and a landmark in the history of science ...[ ]...No more ice, not much of echinoderms, plenty of fish..."
Alexander von Humboldt in a letter to Agassiz on 2. December 1837

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

"advice - never try & persuade ye world of a new theory - persuade 2 or 3 of ye tip top men - & ye rest will go with ye stream, as Dr B. did with Sir H. Davy and Dr. Wollaston in case of Kirkdale Cave"
Edward Jackson, about an advice given by his professor Buckland in 1832

Fig.3. Reconstruction of the glacier that filled the valley of St. Amarin (southern Vosges, France), probably the first tentative reconstruction of an ice age glacier - from COLLOMB (1847): "Preuves de l´existence d´anciens glaciers dans les vallées des Vosges."

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

Fig.4. The Hintereis-glacier (in the centre of the picture), Hochjoch-glacier (left) and the Kesselwand- glacier, drawing by Schmetzer 1891, the Hintereis-glacier is one of the glacier with the longest active monitoring program, values about his length change reach back to 1848, since then the glacier lost 3km of his tongue.
"Aus den tiroler Alpen: Der Abschluß des Oetzthales mit dem Hochjochgletscher (links), dem Hintereisferner (in der Mitte) und dem Kesselwandferner (rechts oben). Nach der Natur gezeichnet von K. Schmetzer (1891)."

These records showed various fluctuations, but from 1850 onward a general trend of recession of glaciers in the Alps is observable. This trend has experienced a strong increase in the last 50 years, causing concern for the fast change in the landscape, the destabilisation of the rock walls once supported by the melting glaciers and the alteration of the discharge and hydrology of mountain ranges.

Fig.5. Temperature rise in the Alps and length loss of the glaciers of the Ötztaler Alps (western Austria) in the period 1900-2010. The valley glaciers with their tongues extending in the valleys showed the strongest retreat and degradation of the studied Austrian glaciers.