Frost Weathering Cave

Auswitterungshöhle


An Auswitterungshöhle, also known as a Frost Weathering Cave, is created by erosion, i.e. mechanical weathering, primarily by frost weathering.

The term Auswitterungshöhle (‘weathered cave’) is a classic cave name that was coined as early as the 19th century. At that time, research was very active, especially in Austria, hence the German term, and the typical shelters, rock overhangs and grottos of the Alps were investigated. It was found that these shelters were obviously not karst caves, despite the fact that they were formed in limestone. Statistical analyses even led to the conclusion that in many karst areas there were more such caves than true karst caves.

Of course, due to their short length, these caves are not comparable in terms of passage length. However, it was soon discovered that both humans and animals usually only used the entrance area of caves. These shelters were therefore extremely important from a palaeontological and archaeological point of view despite their shortness.

The initial assumption was that such caves were formed by weathering with the help of rainwater. In contrast to other erosion caves, no flowing water or wind is required. They are often located in an area of the rock face where a less hard layer has been cut or a fault zone has already disrupted the rock. They are also often found at layer changes between different rock packages. There is also frost weathering, all those forms of physical weathering that are caused by the formation of ice within rock outcrops. Frost weathering is based on the increase in volume of water when it freezes, which creates considerable forces that disrupt the rock. Rainwater penetrates the crevices, and when it freezes, the rock is shattered and more or less falls off by itself, or is washed away by the next rainfall.

Another related mechanism is a combination of dissolution and weathering. Thin layers of rock that are soluble in water are dissolved by rainwater and the rock disintegrates into blocks.

But just to clarify: this type of cave formation is widespread in shelters, but that does not mean that every shelter is of this type. Many shelters are formed on the slopes of rivers, in the surf of the sea, by selective weathering of weak rock, or behind waterfalls. It can be quite difficult to determine which type a cave belongs to.


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