Bohsdorfer Diapir

The sharply cut longitudinal valleys known as giesers are among the most striking morphological landforms in the Muskauer Faltenbogen. They did not arise in the course of the upwards compression of the Faltenbogen, but rather represent the result of a completely independent process. As a result of glacial compression, the clay, sand and lignite layers in the bedrock are folded or steeply tilted, causing them to crop out at the surface. At the earth’s surface, the lignite begins to oxidise under the influence of oxygen in the air. The oxidation process is associated with a loss in volume of the lignite, causing the ground above the coal seam to sink. So-called diapirs represent one particular fold structure. These are upright folds in which the layers in the fold core have breached the “roof” (the bend range of the fold).