Windkanter
Wind edges are rocks that have been ground into a characteristic, often keel-like shape by sand carried by the wind ( wind grinding ).
Emergence
Wind canters are created either from rock fragments that have already been removed from the rock compound of the standing , or from larger particles that are embedded in loose rock (e.g. sand or gravel). They are mechanically processed by the corrosion of the wind. The sand is transported through reptation and saltation and acts as an abrasive on the rock. The side of the stone facing the prevailing wind direction ( windward side) is sanded and smoothed, while the side facing away from the wind ( lee side) remains largely unchanged. This results in more or less sharp ridges or edges.
Wind edges made of rocks of low hardness can arise in just a few decades.
A distinction is made between single-edged , double-edged and multi- edged edges according to the number and formation of the ground surfaces ; however, irregular shapes are also very common. Multiple edges are formed when:
- Winches from different directions to grind the stone from different sides
- the stone changed its position one or more times during the process, e.g. B. by solifluction
- Structures drawn out in the processed stone are modeled (e.g. alternating layers of resistant and less resistant minerals resulting from foliation)
distribution
Wind edges occur almost exclusively in areas with little or no vegetation ( deserts ). Depending on the prevailing climatic conditions , it can be dry or cold deserts. Due to later climate changes (e.g. warming at the end of the Ice Age ), however, wind chanter can also appear as a relic in areas where they would no longer arise today. For this reason, wind canters are very widespread, for example in the moraine landscapes of northern Germany, which was a cold desert or steppe during the most recent, the Vistula Ice Age ( periglacial ). Since the wind canters there are also ice-age debris , one also speaks of wind-ground debris.
As a special case, wind canters can also arise from ice canters or at least from stones pre-ground by the ice.
The formation conditions for wind canters are also given on Mars . Jake Matijevic (rock) is an example of such a form of erosion on Mars.
See also
Erosion , mushroom rocks , glacier cut
literature
- Franz-Dieter Miotke: The formation and formation speed of wind cutters in Victoria Land, Antarctica . In: Polarforschung Vol. 49, No. 1, 1979, pp. 30–43, hdl : 10013 / epic.29469.d001 (PDF; 1.66 MB)
Web links
Individual evidence
- ↑ Patrick Zasada: Formation of the Martian rock "Jake Matijevic". - Sternzeit - magazine of astronomical associations, 2/2013 page 98 ff.