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In the guest blog, geologist and librarian Thomas Hofmann looks at the results and experiences of the excursions at the 1903 Geological Congress in Vienna.
In August 1903, the ninth International Geological Congress attracted a diverse audience of experts (393 participants, 23 of whom were women) to Vienna, where the specialist lectures took place at the University of Vienna from August 20th to 27th. The wide range of 21 excursions on offer met with widespread interest. It ranged from day trips around Vienna to multi-day excursions from the Alps over the Tatra Mountains and Bosnia to Lviv and southern Dalmatia. This led to a revolutionary realization, namely the discovery of the largest geological structure in the Eastern Alps, the Tauern Window. It was therefore proven that the Alps were formed by overthrusting of rock units. And on top of all this, there was impressive evidence of local hospitality for the guests.
Before the French geologist Pierre Termier (1859–1930) attended the congress in Vienna, he went on an excursion to the Tyrolean part of the Tauern in July 1903. Under the leadership of the mineralogist Friedrich Becke (1855–1931) he took part in the eight-day excursion to the Eastern Alps. The central topic was the crystalline rock units of the Hohe Tauern in the Zillertal area, consisting of the central gneiss and the slate cover. The doctrine at the time was that the calcareous phyllites (slate rocks that were formed from calcareous parent rock under the influence of pressure and temperature) of the slate shell came from the Paleozoic (Earth Age). This made sense according to conventional wisdom, as the oldest rocks were at the bottom.
Termier, coming from the Western Alps, was familiar with the rock world there. He knew the "Schistes lustrés" (German: Glanzschiefer) from France and the Graubünden slate from Switzerland, both from the Mesozoic Era. These slate rocks, like the calcareous phyllites, belong to the group of metamorphic rocks (transformational rocks or metamorphites). They arise in the course of mountain-building processes under the influence of pressure and temperature. Since it is not possible to see with the naked eye when this rock transformation (metamorphism) took place, the age of the rocks could not be determined at the time.
After the excursion in the Zillertal, Termier, in a daring thesis, paralleled the "schistes lustres" of the Western Alps that he was familiar with with the calcareous phyllites of the Hohe Tauern. In other words: He saw the calcareous phyllites of the Hohe Tauern, which had previously been believed to be Paleozoic, as an eastern equivalent of the rock series known to him from the west. He correlated them as an extension of the Mesozoic "Schistes lustrés" over the intervening Graubünden slates of Switzerland, whose age was assumed to be Mesozoic. It was therefore logical for the Termian coming from the west that the slate rocks of the Alps would also be of the same age.
In doing so, Termier repostulated the age of the calcareous phyllites in the Tauern: instead of the Era, he spoke of the Mesozoic. The classic theory of geology ("Law of Storage"), that old rocks lie below and younger ones follow above, no longer applied in the Tauern. According to Termier's thesis, older rocks lay above younger ones in the Eastern Alps. This was a reversal of the geological world view. In other words: A new structure, the Tauern Window, had been discovered! This 120 km long structure extends from the Brenner Pass (Tyrol) in the west to the Katschberg region (Salzburg / Carinthia) in the east. The north-south distance varies between 40 and 60 km.
Together with the Swiss geologist Maurice Lugeon (1870–1953), Termier was one of the protagonists of nappe theory. Accordingly, mountains consist of a series of rock units (ceilings) pushed one on top of the other. This theory, which was still young at the time, found acceptance and application in the Western Alps. With Termier's layer correlation it had also reached the Eastern Alps. Since, according to Termier's thesis, the crystalline slate rocks of the Western Alps continue underground into the Eastern Alps, the origins of the Eastern Alps had to be rewritten. According to Termier, the rock ceilings of the Eastern Alps were pushed over those of the Western Alps. The western Alpine rocks are visible in so-called tectonic windows.
The windows were formed as follows: In the course of the Alpine mountain formation, which in terms of plate tectonics corresponds to the collision of the African and Eurasian continental plates, huge overthrusts initially occurred. Series of rocks that were originally next to each other were pushed over one another by tectonic forces. This was followed by the lifting and bulging of the Alpine body, which was created as a stack of layers and whose structure may therefore be reminiscent of an onion. The subsequent erosion begins in the highest parts. This is how the underlying rock series came to light - as if in a window. The older rock series were still preserved on the sides. It's like cutting a piece off the side of an onion.
In the Hohe Tauern area, Termier became the discoverer of the Tauern Window. The slate rocks of the Mesozoic period known from the Western Alps can also be seen in tectonic windows in the Engadine (Engadin Window) or far to the east, in the Rechnitz area (Rechnitz Window). They are framed by partly older rocks from the Eastern Alps, which were pushed over them as blankets. In the specialist literature, these western Alpine rock deposits are referred to as the Penninic, as deposits of the former Penninic Ocean (Jurassic / Mesozoic).
Termiers veni, vidi vici, the details of which were still controversially discussed, was not easy to digest! But greats like Eduard Suess (1831–1914), whose magnum opus, the three-volume "Face of the Earth", was in its final stages at the time, went with termier d'accord. Suess wrote in 1909 in Volume 3 (Part 2) on page 121: "The opinion was expressed that the entire 480-kilometer-long zone of the Eastern Limestone Alps was floating on foreign soil."
Of course, not all excursions had such far-reaching consequences for science. Most of the meetings of scholars were aimed at exchanging knowledge and getting to know new rock and fossil deposits. Since the conversation was never too short, they were never forgotten. So on August 21, 1903, at seven o'clock in the morning, a geological trip started at the Südbahnhof with the destination Atzgersdorf, Baden and Vöslau on the thermal baths line south of Vienna. The purpose of the scientific excursion was twofold. In addition to "research and education" on the deposits of the middle Miocene (16.0 to 11.6 million years), the focus was also on "enjoying nature in the Vienna area and social entertainment". Theodor Fuchs and Franz This may have been successful, because "during the whole game there was little sense of the seriousness of science; there was only laughter and jokes and happy faces; all the professors were in a cheerful mood and in good spirits." ("Neue Freie Presse", August 22, 1903). The society was diverse.
The “Neue Freie Presse” described the participants as follows: Here the “real German professor type (…) in adventurous tourist gear”. There are “young, elegant Englishmen, Spaniards and Russians”. The latter stood out because of their high boots. The clergy were also represented, Father Jaime Almera Comas from Barcelona wore a cassock. Daughters and wives did not shy away from complaints in order to "support the father or husband in his scientific investigations." Marie Jerosch (assistant to Professor Albert Heim) from Zurich was particularly interested. "The pretty young girl tapped the rock with her geologist's hammer and climbed along through thick and thin with a zeal that made it a joy." Despite the heat, the enthusiasm of the scholars was unbroken when it came to the 15 million year old Leitha limestone in the Rauchstallbrunngraben: "They sat, crouched and rode on the rock so that you thought you were seeing a layer of stone hammerers doing their arduous daily wage work." Of course, the Schlumberger winery was also a must. The boss himself, Robert Schlumberger von Goldeck (1850–1939), emphasized the wine's dependence on the soil type and thereby established a connection with the thirsty geologists. After dinner in the Baden Kursalon we went back to Vienna at 9.30 a.m. As a souvenir there was an album with views of Baden.
On August 23rd there were two excursions on the program, both of which went to northern Lower Austria, one to the Kamptal, the other to Eggenburg. In addition to Fuchs and Schaffer, the young Othenio Abel (Imperial Imperial Geological Institute), who made negative headlines for his anti-Semitic activities, led the approximately 50 participants. Among them was Father Jaime Almera Comas again, as well as Charles Depéret from Lyon and Carl Christian Gottsche and his wife from Hamburg - she was the only female participant in the excursion. In addition to the deposits around Eggenburg (Lower Miocene) that are around 20.5 to 17.5 million years old, the aim was the Krahuletz Museum, whose name was already well known among experts back then.
After departing from Franz-Josefs-Bahnhof at 6:50 a.m., the scholars reached Eggenburg at 9:15 a.m. Before heading into the city, from whose roofs flags were flying, the geologists - right next to the train station - devoted more than two hours to the "so-called Eggenburg layers of light gray, coarse quartz sand, which contain thick-shelled oysters." Then, as it had to happen in the Weinviertel, there was the obligatory invitation to a wine cellar. Mayor Leopold Apfelthaler invited people into his cellar, served Röschitzer wine and was convincing. "The French even gave their opinion that the taste of the wine was close to that of Bourgogne grape juice." ("Neue Freie Presse", August 24, 1903).
Johann Krahuletz (1848–1928), museum founder, internationally networked collector and local historian, was waiting for the scientists at the Krahuletz Museum. After his visit, everyone agreed that, thanks to Krahuletz's 40 years of collecting, the museum was a first-class treasure trove for geologists and paleontologists. Depéret had provided the proof. He had already come to Eggenburg in earlier years, worked on the fossil vertebrates of the Eggenburg area and named the remains of a manatee, in Krahuletz's honor, "Metaxytherium krahuletzi". At lunchtime we dined at the Golden Lion. In the afternoon we went along a “dusty, shadowless road” to Gauderndorf. At 7:06 p.m. we started the journey home.
At the beginning of the 1990s, the will was formed in the local geological community to bring the 32nd International Geological Congress (IGC) back to Vienna in 2004 - with a view to the 100th anniversary of the breakthrough in nappe theory. Austria's candidacy was officially announced in 1992 at the 29th IGC in Kyoto, Japan, and initially found broad support. But in 1996 Italy also came onto the scene and also ran. The 39-member Austrian delegation took part in the 31st IGC in Rio de Janeiro (August 6th to 17th, 2000) under the motto "Where science meets history". They advertised an inflatable, walk-in ball with Mozart (Mozartkugel association) on one side and the world 250 million years ago on the other side. Gumpoldskirchen wine, coffee and Mozartkugeln were served.
In the all-important vote, Florence impressed with the motto “Renaissance of Geology” and was awarded the contract with 92 votes. Only 56 people voted for Austria. Regardless of this, numerous local geologists attended the congress in Florence in August 2004 and supported the Italians with excursions in the Alps. (Thomas Hofmann, August 18, 2023)