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Volcanoes

Vysker

Vyskeř is a remnant of a small volcano on the northern edge of the village having the same name. The path starting behind the church leads to an abandoned quarry on the southern foothill. The pyroclastics are medium to fine grained with well visible bedding inclined down the slope. That means, there are superficial facies of a small monogenic volcano preserved on Vyskeř. High degree of fragmentation corresponds to phreatomagmatic eruption. Vyskeř is another example of a tuff cone in the Bohemian Paradise area. The peak of Vyskeř consists of picrite. This rock is in the entire area of Bohemina Paradise the most basic and the richest in MgO and Cr. This is due to cumulitic character of this rock. The crystallizing olivine started to accumulate at the bottom of the magma chamber. As the volcanic activity started, first were emitted lavas depleted in olivine. These lavas were already eroded. The last phase enriched in olivine emplaced in to the feeder of the volcano, where it solidified. Olivine is dominating this rock (about 15 % of olivine exceeds the amount of olivine which would be in equilibrium with the melt – due to cumulitic origin). There are also cliniopyroxene phenocrysts present and a groundmass of clinopyroxene, magnetite and analcime. Olivine phenocrysts enclose chromite.

Chapel st. Anna

Way of the Cross

View of Trosky castle

GPS position

N 50° 31.915', E 15° 9.599'
[GPX]

[MAPY.CZ]

Contact

Geopark UNESCO Český ráj
Jiří Vlasák
e-mail:vlasak@geopark-ceskyraj.cz
http://www.geopark-ceskyraj.cz