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166 lines
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<title>CUCC Austria Expeditions: Geological Outline</title>
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<h1>Loser Plateau: Geology and Speleogenesis</h1>
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<p>
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As it's quite hard to find information about the geological history of the
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Schwarzmooskogel in English, I started investigating. Not that I'd know much
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about geology, but as a German native speaker I had a large selection of
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literature available. Particularly helpful was the article
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"Joachim Kuhlemann et al. . "Eine Zeitreise in den zentralen Nördlichen
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Kalkalpen: von Tropischen Küstenebenen zu Eishöhlen. In Karst und Höhle 2002/2003, Der Schwarzmooskogel, p. 137-153. VdHK e.V. München.
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ISSN 0342-2062", but all the other articles in that journal issue are highly
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recommended as well. At the time of writing, there are furthermore two short
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articles on the appearance and sedimentation of the limestone
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<a href="http://expo.survex.com/geolog.htm">here</a> and
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<a href="http://expo.survex.com/years/1987/geolog.htm">here</a>.
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</p>
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<hr>
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<p>Locally-hosted copies of extensive archive of geology and cave formation papers:
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<ul>
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<li><a href="/expofiles/documents/cave_science_articles/structural-geology/">
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Structural geology</a>
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<li><a href="/expofiles/documents/cave_science_articles/speleogenesis/">
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Speleogenesis</a>
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<li><a href="/expofiles/documents/cave_science_articles/landscape-evolution-paleoclimate/">
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Paleoclimate and landscape</a>
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<li><a href="/expofiles/documents/cave_science_articles/">
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Other cave science articles</a>
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<li><a href="/expofiles/documents/cave_science_articles/german-stuff/">
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(papers in German)</a>
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</ul>
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<h2>Formation of the Limestone</h2>
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<p>
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There appears to have been a shallow sea in the area during the Permian
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(299-251 Mya), which occasionally dried out. This is where the salt of the
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nearby salt mines formed, interspersed with some sandstone sediments. Most of
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the limestone then formed in the middle to late Triassic (250-200 Mya), when
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the shallow sea got a bit deeper, but was still well within reach of sunlight.
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This provided perfect conditions for algae and corals, which eventually turned
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into limestone. The base rock was sinking at the time, but the enormous
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production of sediments counterbalanced this downwards movement. These layers
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of sediments are nowadays called Dachstein-limestone ("Dachsteinkalk").
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</p>
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<p>
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At the end of the Triassic and during the Jurassic (199-145 Mya), the sink
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rate increased and the production of sediments could not keep up any more.
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At the resulting deeper levels of the sea, dolomites and other limestones
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started to form. In our area, the Loser-group and Bräuningzinken are
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examples of these Jurassic limestones and dolomites. Due to various other
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minerals mixed into the rock, it is not as well suited for cave formation as
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the Dachsteinkalk, although major caves are still found (e.g. at Almberg).
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</p>
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<p>
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Towards the end of the middle Jurassic, a new oceanic ridge started to form
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between the Eurasian plate in the north and the Apulian and Adriatic plates in
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the south. Due to the force this new Penninian ocean ridge exerted onto the
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continental plates, the various layers of limestone and dolomite were pushed on
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top of each other in so called thrust faults from the southeast to the
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northwest. Some parts of the newly formed oceanic crust were uplifted as well,
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and at the same time rocks were eroded and started back-filling the ocean. This
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ocean lasted up to the middle Cretaceous (145-65 Mya), when the ocean started
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to close again due to a change in tectonics. The subduction of the short lived
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oceanic crust continued a few more million years and the ocean has completely
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disappeared nowadays. In the process rocks were also eroded from the bottom of
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the continental crust by friction of the subducted oceanic crust. Generally
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the area around the Totes Gebirge also sunk a bit during the late Cretaceous
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and early Paleogene (65.5-23 Mya).
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</p>
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<h2>First Caves and Mountains</h2>
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<p>
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During the Eocene (55.8-33.9 Mya) the alpidian collision started to cause the
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uplift of the Alps. However, in the beginning this mostly caused an uplift in
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the western part of the Alps, and the eastern part including the Totes Gebirge
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was still relatively low, even partially flooded by seawater. As a result, a
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first karstification started in the area, which created what is called the
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cave ruin level ("Ruinenhöhlenniveau"). This level is nowadays about 1800m
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and higher above sea level and the stone bridge (Traungoldhöhle) is probably
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a prime example of this cave level.
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</p>
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<p>
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However, the new mountain ridge to the southwest of the Totes Gebirge was
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exposed to erosion and lots of sediments started to back-fill and cover the
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cave ruin level in the Oligocene (33.9-23 Mya). The new sediments are called
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Augenstein-Formation, and the rubble consisted of all kinds of odd materials
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like quartz, gneiss, slate, some ore, sandstones and others. The sediments are
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getting finer in the north and fine sands at the northern edge of Totes Gebirge
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indicate that a coastline was present at the time, whereas coarser pebbles
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and stones are found further south. The exact mineral composition of the
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Augenstein-sediments found at various places even allows to reconstruct the
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river network of the time, which was mostly oriented south to north.
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Furthermore the absence of gneiss and slate in the Augenstein-sediments of the
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Totes Gebirge indicate that these rocks, which nowadays form the Tauern
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mountains south of our area, were mostly covered by limestone and other
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sediments at the time. These sedimentary rocks are nowadays only present around
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some peaks of the Tauern mountain range. Some rock metamorphosis has taken
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place in the Augenstein-sediments and indicate a thickness of at least 1300m up
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to maybe beyond 2000m, with a maximum of thickness around the Dachstein area.
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</p>
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<p>
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In the early Miocene (23-5.3 Mya) the eastern Alps were laterally stretched in
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the east-west direction by more than 50%. This event also caused a collapse of
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the mountains further south-west, a new layout of the river network along the
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newly formed fault lines, and in the cause of both a complete stop of the
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sedimentation of Augenstein-layers. Most of these sediments had been eroded
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again by about 10 Mya. Karstification of the cave ruin level and below could
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start again.
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</p>
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<h2>More Caves</h2>
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<p>
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During the last 10 Mya, the Totes Gebirge was raised by about 2000m, which is
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equivalent to about 2mm per year. This uplift is generally considered to have
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happened in distinct phases instead of a continuous process, as there appear
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to be distinct levels of caves all around. The "level of big caves"
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("Riesenhöhlenniveau") with extensive horizontal passages is nowadays at
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around 1550m-1640m above sea level. It was formed in the late Miocene, about
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10 Mya.
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</p>
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<p>
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Due to the absence of plants and due to glaciation and hence absence of flowing
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water, there was hardly any new cave formation in the Pleistocene (2.5 Mya -
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10 Kya). However, most recently the level of spring caves
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("Quellhöhlenniveau") has formed and is still actively forming at
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altitudes equivalent to the present valley bottoms. As the distance of this
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spring cave level to the older levels varies between 700m and 1000m in various
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parts of the Alps (Tennengebirge, Steinernes Meer, Totes Gebirge), it is
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believed that these different places have also been lifted by different rates
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in the Pliocene era (5.3-2.5 Mya).
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</p>
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<p>
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It is obvious that the above geological history of the Totes Gebirge is mostly
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an interpretation of the sparse evidence that is nowadays found at Dachstein,
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Schönberg, Schwarzmooskogel, Woising, Tauplitz and the other areas.
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New finds and new caves might necessitate a complete or at least a partial
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rewrite.
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</p>
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<p><i>Olaf Kähler, September 2012</i></p>
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<hr />
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Link to <a href="https://en.wikipedia.org/wiki/Eastern_Alps">Wikipedia: Eastern Alps Geology</a>.
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<br />
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Link to <a href="geolog2.htm">Anonymous Geological Outline (2015?)</a>.
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<br />
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Link to <a href="years/1987/geolog.htm">Jared's Geological Guide (1988)</a>.
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<br />
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Link to <a href="years/1981/cavdev.htm">Tony Malcolm's Geological Guide (1982)</a>.
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<br />
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Link to <a href="https://onrappel.blogspot.com/2018/05/dachstein-massif-geology-intro.html">Excellent long article on Dachsteinkalk</a>
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<hr />
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</body>
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</html>
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