General Characteristics

County (administration): Liberec Region
District (town): Semily
Cadastre: Vesec pod Kozákovem
Map 1 : 50 000 (sheet No): 0332, 03324
Geological region: Czech Cretaceous Basin - Labe & Čáslav Cretaceous; Cretaceous of the Dlouhá mez
Accessibility: - no traffic restriction ( by car)
ID : 3203

Geology

Short characteristics of the site: The volcanic deposits of the Prackov volcano are exposed by several outcrops on its slopes. Significant depression on the top of the hill represents remnant of a crater. The basal pyroclasticks exposed in the stream are intensively fragmented (the grain-size varies about 1 cm) rich in xenoliths of Cretaceous sediments. These fine-grained pyroclastics were produced during initial phreatomagmatic phase of the volcanic activity. Upwards, the grain size of pyroclastic deposits increases and xenolith content decreases. The pyroclastic deposits are dominated by vesicular sciria fragments with spindle-shaped bombs. Some bombs enclose peridotite xenoliths. The upper pyroclastics correspond to Strombolian type of volcanic eruption. The lava of Prackov volcano has been dated to 4,92 Ma (K/Ar: Cajz et al. 2009).
Regional geologic unit: Bohemian Massif - superficial deposits and post-Variscian magmatites - Tertiary - Dispersed Alcalic volcanits
Stratigraphy: kenozoikum - terciér (paleogén - neogén)
Subject: volcanology
Geological phenomenon: outcrop, cinder cone, lava
Genesis: volcanic
Rock: pyroclastic deposits

Territorial conservation

Level of protection: Interesting geological localities in Protected landscape area
Protection of a geol. phenomenon: C - Geological phenomenon is the reason for a registration in the database of CGS
Part of LEPA (Large-size especially protected areas): CHKO (Protected landscape area) - Český ráj
Part of the Geopark: Bohemian Paradise
Conflicts of interests: without conflicts

References

Raprrich, V., red. (2011): Základní geologická mapa České republiky 1 : 25 000 s Vysvětlivkami 03-324 Turnov. - Česká geologická služba. Praha.; CAJZ, V. – RAPPRICH, V. – SCHNABL, P. – PÉCSKAY, Z. (2009): Návrh litostratigrafie neovulkanitů východočeské oblasti. – Zprávy geol. výzk. v roce 2008, 9–14.

Elaboration and Updating

Elaborated by: Rapprich Vladislav, 14.07.10
Updated by: Rapprich Vladislav 08.11.11

Citation

The database Significant geological localities of the Czech Republic: 3203 [online]. Prague: Czech Geological Survey, 1998 [cit. 2024-04-26]. Available from: http:// lokality.geology.cz/3203.

Location in map: