Geology of Austria


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Hochtor (2369 m asl), showing folded limestone rocks, Austria. Public Domain.
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Geologic map of the Alps. Public Domain.
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The Oberer Hauptdolomit (slanted dolomite layers) in the Reither Kar, Erlspitz-Group, Karwendel, Austria. Public Domain.
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Folded serpentinite, near Geierjoch, Tuxer Alps, Austria. Public Domain.

Most of Austria’s surface is covered by the Alps, and most of its caves and mines are also in the Alps. So we concentrate on the geology of the Alps. This mountain ridge divides Europe from the east to the west. It starts in the west at the Rhone valley, around Grenoble. Then it crosses Switzerland and Austria and ends south of Vienna, close to the Austrian Hungarian border. This mountain ridge was formed by the alpine orogeny, which is a result of the collision of the European and the African plate.

The orogeny started more than 150 Million years ago when the Atlantic ocean opened up. As a result of this movement, the African and European plates collided. First, there was a downlift, forming a basin which was filled with sediments. But the mechanical compression of the rocks also started a process of folding and thrusting of the sedimentary rocks. Later, during the last 10 or 15 Million years, packages of rocks, called thrust sheets or nappes, were pushed on top of each other. This made the plate thicker, and as a result it was not in the isostatic equilibrium any more. This process culminated in the actual uplift of the Alps which has been going on for the last 10 Million years. The Alps are lifted continually, and the erosion continually erodes material at the same time, which is more or less in an equilibrium. The reason is simple: if the movement becomes faster, the summits go up, and erosion speeds up.

A cross-section of the Alps shows a certain symmetry: the northern and southern ridges are composed of limestone, the center is composed of crystalline rocks. A simplified explanation is: the center is formed by older rocks which come from a greater depth. The uplift is higher in the center and gets continually lower to the north and south.

Caves

The Austrian caves are located in the limestone ridges of the Nördliche Kalkalpen or the Südliche Kalkalpen (northern and southern limestone Alps). In these mountain ridges, many large caves can be found, spacious cave systems with many vertical shafts and huge chambers, which are often called alpine caves or caves of alpine type.

The geography, with high limestone mountains and deep valleys, is a precondition for really deep caves. The deepest caves of the world are found in such areas: the Pyrenees, the Rocky Mountains, the Alps or the Ural. The deepest cave of Austria, the ShowcaveLamprechtsofen, has a vertical range of 1,727 m [2024]. A few decades ago it was the deepest cave of the world, but cave exploration continues, and now it is the 6th deepest cave of the world [2024].

These caves are high above sea level, their genesis seems impossible under today’s climatic conditions. They were formed during times with other temperatures and climate. Either it was warmer with much more rain, or there were glaciers, which produced high amounts of melting water during summer. Another theory is that they formed at a lower location and were uplifted during the last 10 Million years together with the rocks.

Mining

In Austria, the mining industry started thousands of years ago and brought wealth and power to their ancestors. In the 1970s and 1980s, many mines had to be shut down for economic reasons. A long tradition came to an end. Show mines try to keep up some of these traditions by giving a general idea of the dangerous working conditions below the surface of the earth.

Austria has a wealth of different mines, and many are developed as tourist mines. Because of the fortunate geology in these mountains, a broad range of minerals and ores can be found. And during the centuries the mining technology changed, so many different kinds of mines existed in this country. Visiting some mines gives a good insight in at least 2,000 years of mining history.