česky english deutsch <<< >>>

Besedice Rocks

Weathering

The extensive outcrop of Besedice rocks within the Bohemian Paradise has a profound influence on the landscape. Weathering of the alternately hard and soft beds has produced a highly distinctive terraced form to many of the hillsides. Ssandstones are typically resistant to erosion, compared to interbedded shales. These hard beds thus tend to find expression as steeper slopes and cliffs. Which kind of weathering predominates depends upon the type of rock and climate. Chemical weathering attacks chemical ingredients in rocks. Chemical weathering attacks rocks aggressively in humid climates. The chief destructive agents are rainwater and substances that it contains. Physical weathering destroys rock but leaves its chemical composition unchanged. Physical weathering is active chiefly in cold or dry climate. Agents include sharp temperature changes, frost drought, crystallizing salts and plants. Organic weathering involves organic acids produced by organism as bacteria, lichens, mosses, and decaying plants of many kinds. The acids attack rock-forming minerals. Exfoliation is the flaking of intensely heated surface rock as it expands more than the cooler rock below.

Pressure release follows removal of overlying rock and its pressure on the rock below. Expansion of that rock then forms curved joints promoting sheeting of rock shells from the inner mass. Dissolved salts expanding as they dry and crystallize in rock split the rock and honeycomb its surface. Weathering of sandstone accentuates the horizontal bedding planes and vertical joints in sandstone masses.

Weathering makes layering

The form of physical weathering is rock window

GPS position

N 50° 37.729', E 15° 11.956'
[GPX]

[MAPY.CZ]

Contact

Geopark UNESCO Český ráj
Jiří Vlasák
e-mail:vlasak@geopark-ceskyraj.cz
http://www.geopark-ceskyraj.cz