Spheroidal weathering

The Wollsackverwitterung (rarely also called " mattress weathering" ) is a special form of weathering of rocks. Through the interaction of physical and chemical processes occur during the Wollsackverwitterung edge- rounded boulders that are like pillows, mattresses or even as wool sacks stacked. The visual concept of ' wool bag "derives it filled with coarse wool sacks from that were used historically in particular both as a sleeping pad as well as for the transport of wool.

Weathering processes

Mainly in coarsely crystalline rocks such as granite, quartz porphyry and gneiss, but also in massive sandstone weathering this form makes its appearance around the world. So-called wool bags often come in the form of largely free of vegetation rock castles before, for example at the Extern Stones and in many places in the Harz Mountains, in the Black Forest, for example, at the Karlstejn in Hornberg, in Myanmar (such as Golden Rock ), in the devil kitchen in the Upper Palatinate Forest or areally in the form of rocks seas, eg in Luisenburg rock labyrinth in the Fichtelgebirge, in the Blockheide ( Waldviertel, Lower Austria ) or in the sea cliffs in the Odenwald. In the Saxon Erzgebirge is, inter alia, the " Hefekloßfelsen " in width Brunn / Erzgeb. a popular destination. Also known are the " gate " mentioned distinctive granite rock in southern England.

Basics of woolsack - emergence are weathering processes on solid rock masses below the soil surface. Usually arise in the course of time near the surface cracks and fissures in the rock and thus basically square blocks. This process is called jointing. The frost damage can play an important role.

In the banked, cross - stones or längsgeklüfteten then penetrate chemically aggressive solutions (rain water or dissolved in the water humic acids ) and begin to decompose the minerals of the rock. This is done in the first place at the corners and edges of the individual blocks, because there the engagement surfaces are larger than on the side surfaces. This sharp and angular positions of the blocks are rounded. Due to the fundamental loosening of the structure of the stones disintegrate while superficially to fine-grained loose Grus. This process is referred to as Abgrusung or Vergrusung. Partly it comes to scaling coherent thin rock plate, the so-called desquamation. Favors the chemical dissolution processes by alternating wet and warm climates of the tropics and subtropics.

The wool bag weathering is terminated by exposure of the rock blocks when soil and weathering residues are carried away, eg by soil erosion. Because of the lack of Vegetationslosigkeit and land cover often adventurous -looking rock formations are then exposed to other forms of weathering.