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<h1>Outline Geology of the Loser Plateau</h1> <h1>Loser Plateau: Geology and Speleogenesis</h1>
<p>
As it's quite hard to find information about the geological history of the
Schwarzmooskogel in English, I started investigating. Not that I'd know much
about geology, but as a German native speaker I had a large selection of
literature available. Particularly helpful was the article
"Joachim Kuhlemann et al. . "Eine Zeitreise in den zentralen N&ouml;rdlichen
Kalkalpen: von Tropischen K&uuml;stenebenen zu Eish&ouml;hlen. In Karst und Höhle 2002/2003, Der Schwarzmooskogel, p. 137-153. VdHK e.V. München.
ISSN 0342-2062", but all the other articles in that journal issue are highly
recommended as well. At the time of writing, there are furthermore two short
articles on the appearance and sedimentation of the limestone
<a href="http://expo.survex.com/geolog.htm">here</a> and
<a href="http://expo.survex.com/years/1987/geolog.htm">here</a>.
</p>
<p>Much of the area of the Loser Augst-Eck plateau is rough limestone pavement <h2>Formation of the Limestone</h2>
(<b>karren</b>), liberally covered with dense areas of dwarf pine, and <p>
interspersed with small cliffs, open shafts and snow patches. To the new There appears to have been a shallow sea in the area during the Permian
visitor, it all looks alike, and even to the geologist, there are few marker (299-251 Mya), which occasionally dried out. This is where the salt of the
beds and no obvious structure. This tended to produce the attitude that "its nearby salt mines formed, interspersed with some sandstone sediments. Most of
all limestone, with caves in", and little more effort was made.</p> the limestone then formed in the middle to late Triassic (250-200 Mya), when
the shallow sea got a bit deeper, but was still well within reach of sunlight.
This provided perfect conditions for algae and corals, which eventually turned
into limestone. The base rock was sinking at the time, but the enormous
production of sediments counterbalanced this downwards movement. These layers
of sediments are nowadays called Dachstein-limestone ("Dachsteinkalk").
</p>
<p>Articles speculating on the geology appeared from time to time in <p>
<b>Cambridge Underground</b>, written by people with varying degrees At the end of the Triassic and during the Jurassic (199-145 Mya), the sink
of expertise, and based on either limited literature searches or some rate increased and the production of sediments could not keep up any more.
evidence gathered "on the ground" - including a perusal of various cave At the resulting deeper levels of the sea, dolomites and other limestones
surveys. Jared West's <a href="years/1987/geolog.htm">article</a> in C.U. started to form. In our area, the Loser-group and Br&auml;uningzinken are
1988 pretty much summarises the literature. A geologic sketch map of the area examples of these Jurassic limestones and dolomites. Due to various other
is based on "The Geology of the Eastern Alps", by Prof. E.R.Oxburgh (The minerals mixed into the rock, it is not as well suited for cave formation as
Geologists Association, London, 1968):</p> the Dachsteinkalk, although major caves are still found (e.g. at Almberg).
</p>
<div class="centre"><img src="maps/jared.png" width="1258" height="632" <p>
alt="Geological map" /></div> Towards the end of the middle Jurassic, a new oceanic ridge started to form
between the Eurasian plate in the north and the Apulian and Adriatic plates in
the south. Due to the force this new Penninian ocean ridge exerted onto the
continental plates, the various layers of limestone and dolomite were pushed on
top of each other in so called thrust faults from the southeast to the
northwest. Some parts of the newly formed oceanic crust were uplifted as well,
and at the same time rocks were eroded and started back-filling the ocean. This
ocean lasted up to the middle Cretaceous (145-65 Mya), when the ocean started
to close again due to a change in tectonics. The subduction of the short lived
oceanic crust continued a few more million years and the ocean has completely
disappeared nowadays. In the process rocks were also eroded from the bottom of
the continental crust by friction of the subducted oceanic crust. Generally
the area around the Totes Gebirge also sunk a bit during the late Cretaceous
and early Paleogene (65.5-23 Mya).
</p>
<p>From this it can be seen that our area is composed of the massively bedded <h2>First Caves and Mountains</h2>
white Dachsteinkalk limestone of Triassic age. The summit of the Loser and <p>
adjacent peaks is more recent Jurassic limestones. The oldest of these, During the Eocene (55.8-33.9 Mya) the alpidian collision started to cause the
particularly obvious in the Br&auml;uning Wall, are quite thinly bedded Liassic uplift of the Alps. However, in the beginning this mostly caused an uplift in
marls. All these sediments have been pushed NNE in the Totengebirgs-Decke, a the western part of the Alps, and the eastern part including the Totes Gebirge
massive thrust. This is bounded to the SW, roughly along the line of the road was still relatively low, even partially flooded by seawater. As a result, a
from Altaussee to Blaa-Alm, by a thrust plane. SW of this boundary, the surface first karstification started in the area, which created what is called the
is entirely composed of Jurassic sediments, with little of speleological cave ruin level ("Ruinenh&ouml;hlenniveau"). This level is nowadays about 1800m
interest. To the SE, the Loser block is bounded by a fault which runs along the and higher above sea level and the stone bridge (Traungoldh&ouml;hle) is probably
NW shore of the Altausseer See. The Trisselwand is composed of Jurassic a prime example of this cave level.
limestone, younger than the Liassic marls, and is also massively bedded and </p>
seems to contain at least some cave development.</p>
<p>Less obvious is the observation that in the Rettenbachtal to the west of <p>
Loser, Jurassic rocks are again exposed, separated from the Dachsteinkalk However, the new mountain ridge to the southwest of the Totes Gebirge was
outcrop by a band of Liassic marls, which also extend NE up the valley of exposed to erosion and lots of sediments started to back-fill and cover the
Gr&uuml;ne Bichl. This is apparently the trace of a second thrust plane, cave ruin level in the Oligocene (33.9-23 Mya). The new sediments are called
(higher than the one shown on the map above) where the Dachsteinkalk has Augenstein-Formation, and the rubble consisted of all kinds of odd materials
effectively slid north lubricated by a layer of salt (which itself is most like quartz, gneiss, slate, some ore, sandstones and others. The sediments are
obvious in the local Salzbergwerk - salt mines). This suggests that the getting finer in the north and fine sands at the northern edge of Totes Gebirge
situation is rather more complex than the single thrust depicted above, but, if indicate that a coastline was present at the time, whereas coarser pebbles
true, at least eliminates the idea that the Loser plateau is a nappe, with and stones are found further south. The exact mineral composition of the
these lower beds inverted, and a shattered core at half the depth of the Augenstein-sediments found at various places even allows to reconstruct the
Dachsteinkalk which would prevent exploration to great depth. This is river network of the time, which was mostly oriented south to north.
supported by direct exploration of the Stellerweg streamway, which has reached Furthermore the absence of gneiss and slate in the Augenstein-sediments of the
roughly lake level, which is quite near the level of the main thrust plane.</p> Totes Gebirge indicate that these rocks, which nowadays form the Tauern
mountains south of our area, were mostly covered by limestone and other
sediments at the time. These sedimentary rocks are nowadays only present around
some peaks of the Tauern mountain range. Some rock metamorphosis has taken
place in the Augenstein-sediments and indicate a thickness of at least 1300m up
to maybe beyond 2000m, with a maximum of thickness around the Dachstein area.
</p>
<p>The Dachsteinkalk all looks very similar, and much of the rock underground <p>
is concealed by mud or breakdown, so it has proved very difficult to make any In the early Miocene (23-5.3 Mya) the eastern Alps were laterally stretched in
meaningful observations. It has become clear, however, that all or most of the the east-west direction by more than 50%. This event also caused a collapse of
vertical development in the caves is fault- or joint-guided, on two roughly the mountains further south-west, a new layout of the river network along the
perpendicular sub-vertical sets of faults/joints. That some of these are indeed newly formed fault lines, and in the cause of both a complete stop of the
faults is shown by clear offset of beds in a few places where prominent shelly sedimentation of Augenstein-layers. Most of these sediments had been eroded
beds act as markers. Some faults are also apparent running for significant again by about 10 Mya. Karstification of the cave ruin level and below could
distances on the surface, sub-parallel with the massive fault bounding the start again.
Loser block to the SE.</p> </p>
<p>The fossil phreatic passages seem to be much less dependent on joint <h2>More Caves</h2>
direction, and appear to follow certain beds of the Dachsteinkalk. The clearest <p>
example is Yapate Inlet and Chicken Flied Nice, near Burble crawl in <a During the last 10 Mya, the Totes Gebirge was raised by about 2000m, which is
href="smkridge/161/top.htm">Kaninchenh&ouml;hle</a>.</p> equivalent to about 2mm per year. This uplift is generally considered to have
happened in distinct phases instead of a continuous process, as there appear
to be distinct levels of caves all around. The "level of big caves"
("Riesenh&ouml;hlenniveau") with extensive horizontal passages is nowadays at
around 1550m-1640m above sea level. It was formed in the late Miocene, about
10 Mya.
</p>
<div class="centre"><img src="smkridge/161/fullsize/cfngeo.png" width="600" <p>
height="530" alt="Cross-section sketch of Yapate and Burble Crawl" /></div> Due to the absence of plants and due to glaciation and hence absence of flowing
water, there was hardly any new cave formation in the Pleistocene (2.5 Mya -
10 Kya). However, most recently the level of spring caves
("Quellh&ouml;hlenniveau") has formed and is still actively forming at
altitudes equivalent to the present valley bottoms. As the distance of this
spring cave level to the older levels varies between 700m and 1000m in various
parts of the Alps (Tennengebirge, Steinernes Meer, Totes Gebirge), it is
believed that these different places have also been lifted by different rates
in the Pliocene era (5.3-2.5 Mya).
</p>
<p>Here, the small inlet tube of Burble Crawl, and the original main trunk tube <p>
of CFN are both formed in a massive creamy white bed of limestone just above a It is obvious that the above geological history of the Totes Gebirge is mostly
0.8m thick zone of thinly bedded limestone. At Staircase 36, the beds can be an interpretation of the sparse evidence that is nowadays found at Dachstein,
seen to be offset at a fault running roughly at right angles to the main Sch&ouml;nberg, Schwarzmooskogel, Woising, Tauplitz and the other areas.
passage, and Yapate Inlet, south of the fault, is formed in exactly the same New finds and new caves might necessitate a complete or at least a partial
bed, but a few metres lower in altitude. The much later vadose downcutting has rewrite.
revealed the lower beds including the two shelly beds containing many fossil </p>
bivalves. These fossils stand out particularly well on the wall of Staircase 36
itself, where they provided much-needed holds for the climb.</p>
<p><i>to be continued...</i></p> <p><i>Olaf K&auml;hler, September 2012</i></p>
<hr /> <hr />
<ul id="links">
<li>Back to <a href="../index.htm">CUCC Home page</a></li>
<li>Back to <a href="index.htm">Expedition Intro page</a></li>
<li><b>Main Indices:</b>
<ul>
<li><a href="infodx.htm"><b>Index</b> to Expo</a> information pages</li>
<li><a href="areas.htm">Description of CUCC's area</a> and split to subareas</li>
<li>Full <a href="indxal.htm">Index to cave descriptions</a> in area 1623</li>
<li>List of (links to) <a href="pubs.htm">published reports and logbooks</a></li>
</ul></li>
<li><b>Pictures:</b>
<ul>
<li><a href="gall0.htm">Text only Index</a></li>
<li><a href="gallery/0.htm">Index pages (with thumbnails)</a></li>
</ul></li>
<li>Table of <a href="folk/index.htm"><b>members</b> of CUCC expeditions</a> 1976-present</li>
</ul>
</body> </body>
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<title>CUCC Austria Expeditions: Geological Outline</title>
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<body>
<h1>Outline Geology of the Loser Plateau</h1>
<p>Much of the area of the Loser Augst-Eck plateau is rough limestone pavement
(<b>karren</b>), liberally covered with dense areas of dwarf pine, and
interspersed with small cliffs, open shafts and snow patches. To the new
visitor, it all looks alike, and even to the geologist, there are few marker
beds and no obvious structure. This tended to produce the attitude that "its
all limestone, with caves in", and little more effort was made.</p>
<p>Articles speculating on the geology appeared from time to time in
<b>Cambridge Underground</b>, written by people with varying degrees
of expertise, and based on either limited literature searches or some
evidence gathered "on the ground" - including a perusal of various cave
surveys. Jared West's <a href="years/1987/geolog.htm">article</a> in C.U.
1988 pretty much summarises the literature. A geologic sketch map of the area
is based on "The Geology of the Eastern Alps", by Prof. E.R.Oxburgh (The
Geologists Association, London, 1968):</p>
<div class="centre"><img src="maps/jared.png" width="1258" height="632"
alt="Geological map" /></div>
<p>From this it can be seen that our area is composed of the massively bedded
white Dachsteinkalk limestone of Triassic age. The summit of the Loser and
adjacent peaks is more recent Jurassic limestones. The oldest of these,
particularly obvious in the Br&auml;uning Wall, are quite thinly bedded Liassic
marls. All these sediments have been pushed NNE in the Totengebirgs-Decke, a
massive thrust. This is bounded to the SW, roughly along the line of the road
from Altaussee to Blaa-Alm, by a thrust plane. SW of this boundary, the surface
is entirely composed of Jurassic sediments, with little of speleological
interest. To the SE, the Loser block is bounded by a fault which runs along the
NW shore of the Altausseer See. The Trisselwand is composed of Jurassic
limestone, younger than the Liassic marls, and is also massively bedded and
seems to contain at least some cave development.</p>
<p>Less obvious is the observation that in the Rettenbachtal to the west of
Loser, Jurassic rocks are again exposed, separated from the Dachsteinkalk
outcrop by a band of Liassic marls, which also extend NE up the valley of
Gr&uuml;ne Bichl. This is apparently the trace of a second thrust plane,
(higher than the one shown on the map above) where the Dachsteinkalk has
effectively slid north lubricated by a layer of salt (which itself is most
obvious in the local Salzbergwerk - salt mines). This suggests that the
situation is rather more complex than the single thrust depicted above, but, if
true, at least eliminates the idea that the Loser plateau is a nappe, with
these lower beds inverted, and a shattered core at half the depth of the
Dachsteinkalk which would prevent exploration to great depth. This is
supported by direct exploration of the Stellerweg streamway, which has reached
roughly lake level, which is quite near the level of the main thrust plane.</p>
<p>The Dachsteinkalk all looks very similar, and much of the rock underground
is concealed by mud or breakdown, so it has proved very difficult to make any
meaningful observations. It has become clear, however, that all or most of the
vertical development in the caves is fault- or joint-guided, on two roughly
perpendicular sub-vertical sets of faults/joints. That some of these are indeed
faults is shown by clear offset of beds in a few places where prominent shelly
beds act as markers. Some faults are also apparent running for significant
distances on the surface, sub-parallel with the massive fault bounding the
Loser block to the SE.</p>
<p>The fossil phreatic passages seem to be much less dependent on joint
direction, and appear to follow certain beds of the Dachsteinkalk. The clearest
example is Yapate Inlet and Chicken Flied Nice, near Burble crawl in <a
href="smkridge/161/top.htm">Kaninchenh&ouml;hle</a>.</p>
<div class="centre"><img src="smkridge/161/fullsize/cfngeo.png" width="600"
height="530" alt="Cross-section sketch of Yapate and Burble Crawl" /></div>
<p>Here, the small inlet tube of Burble Crawl, and the original main trunk tube
of CFN are both formed in a massive creamy white bed of limestone just above a
0.8m thick zone of thinly bedded limestone. At Staircase 36, the beds can be
seen to be offset at a fault running roughly at right angles to the main
passage, and Yapate Inlet, south of the fault, is formed in exactly the same
bed, but a few metres lower in altitude. The much later vadose downcutting has
revealed the lower beds including the two shelly beds containing many fossil
bivalves. These fossils stand out particularly well on the wall of Staircase 36
itself, where they provided much-needed holds for the climb.</p>
<p><i>to be continued...</i></p>
<hr />
<ul id="links">
<li>Back to <a href="../index.htm">CUCC Home page</a></li>
<li>Back to <a href="index.htm">Expedition Intro page</a></li>
<li><b>Main Indices:</b>
<ul>
<li><a href="infodx.htm"><b>Index</b> to Expo</a> information pages</li>
<li><a href="areas.htm">Description of CUCC's area</a> and split to subareas</li>
<li>Full <a href="indxal.htm">Index to cave descriptions</a> in area 1623</li>
<li>List of (links to) <a href="pubs.htm">published reports and logbooks</a></li>
</ul></li>
<li><b>Pictures:</b>
<ul>
<li><a href="gall0.htm">Text only Index</a></li>
<li><a href="gallery/0.htm">Index pages (with thumbnails)</a></li>
</ul></li>
<li>Table of <a href="folk/index.htm"><b>members</b> of CUCC expeditions</a> 1976-present</li>
</ul>
</body>
</html>