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Steigerberg: surf cliff of the Oligocene sea
285 million years ago at the geological turning point to the
Rotliegende,
there were strong movements of the earth's crust in the Nahe area with
wavelike shocks and the creation of faults. In the process magma, the
molten material inside the earth, rose towards the surface but without
actually reaching it. The large intrusion blocks created by this movement,
which were later exposed by erosion, are made up of red rhyolite (earlier:
porphyre) —like the Rotenfels and the Rheingrafenstein— or of the somewhat
darker dacite, as found on the Lemberg mountain. Later on, the more liquid
magma reached the surface and covered much of the Nahe area. The lava soon
stopped flowing and was, over a period of 240 million years
(Triassic, Jurassic, Cretaceous periods),
exposed to a mostly tropical climate, where the volcanic rock was
profoundly eroded creating deep valleys. Isolated blocks of very
hard rhyolith have remained, though.
35 million years ago, in the
Oligocene
era, there was a down-faulting which created the trench of the upper
Rhine. The region was flooded by a subtropical sea. This sea
connected to the open seas to the north and south of the middle
European area. The coastline ran along the southern edge of the
Devonian layers of the Hunsrück with shallow bays near Bad Sobernheim and
Bad Kreuznach.
Photo: Surf cliff of the Steigerberg from the Oligocene period.
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