Cenozoic

Another major stage of volcanic activity, related to the Alpine Orogeny, took place in the Geopark territory in the Cenozoic, especially in the Neogene. In spite of the rather indirect effect of this orogeny on the Geopark territory, basaltic magma often penetrated to this area through a series of grabens in the crust associated with the so-called Ohře Rift (now following the Ohře River valley).

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Volcanic products concentrate mainly to the area of the so-called Jičín Volcanic Field, extending over the surroundings of Jičín, Sobotka and Nová Paka. This area displays many remains of volcanic bodies, which are usually morphologically prominent due to their young age (ca. 24–17 million years). They are mostly formed by dark basalt with typical columnar jointing and enclaves of green olivine, which probably comes from depths of about 100 kilometres. The youngest as yet detected age of eruption relates to basalt at Kozákov Hill (7–3.5 million years). 


Created 18.2.2020 14:50:08 - updated 28.2.2020 22:36:10 | read 591x | sprokesova
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