Cross-bedding and erosion surfaces/reactivation surfaces in the sandstones of the Příhrazské skály Cliffs (Bohemian Paradise)


Jaroslav Valečka

Geoscience Research Reports 43, 2010 (GRR for 2009), pages 70–73
Map sheets: Sobotka (03-34)

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The quartzose sandstone body forming the Příhrazské skály Cliffs in the Bohemian Paradise area was deposited in the NE part of the shallow-marine Bohemian Cretaceous Basin. The 90-100 m thick body is homogeneous in its lithology, with no intercalations of other lithotypes. Cross-bedding is the main sedimentary structure, forming sets several centimetres to 6 m thick. One set attains the thickness of 25-30 m. Variable orientations of the foreset laminae indicate an interaction of tidal currents, wind-driven currents, storm-induced currents and semipermanent currents. The cross-bedded units are comparable with ripples and sand dunes occurring in modern shelf seas and straits.