Grus (geology)

As Verwitterungsgrus, Gesteinsgrus or short Grus ( Low German ) is called small, square - edged, irregular pieces of stone caused by Abgrusung. They have a grain size of 2 to 6.3 mm.

When Abgrusung or Vergrusung rock decays mainly by temperature weathering. This Grusbildung depends on the rock material. It occurs mainly in durable, granular rock such as granite, which is composed of different minerals. With a strong temperature changes, the various minerals stretch due to the different thermal expansion coefficients are not uniformly, so that the mineral cohesion gradually loosens. Also in the Wollsackverwitterung arises Verwitterungsgrus.