General Characteristics

County (administration): Liberec Region
District (town): Liberec
Cadastre: Janův důl
Map 1 : 50 000 (sheet No): 0334, 03312
Geological region: Czech Cretaceous Basin - Jizera Cretaceous & Cretaceous of the lower section of Labe River, Ploučnice, Kamenice and the Děčínský Sněžník Mt.
Accessibility: - access without footpath
ID : 3402

Geology

Short characteristics of the site: The outcrop and old mine workings around a tephrite/basanite rock near the locality called "Janův kopec - the John´s Hill". Regionally this locality belongs to "the disseminated alkali volcanics in the Bohemian Massif". The volcanics are surrounded by Cretaceous sediments. This outstanding rock was well known already in the second half of the 19th century. Up to 10 cm large amphibole phenocrysts were described. K-Ar dating brouht some uncertain results - from the Cretaceous up to the Neogene.
Regional geologic unit: Bohemian Massif - superficial deposits and post-Variscian magmatites - Tertiary - Dispersed Alcalic volcanits
Stratigraphy: kenozoikum - terciér (paleogén - neogén), mezozoikum - křída - svrchní křída
Subject: volcanology
Geological phenomenon: dyke, characteristic rock
Genesis: volcanic
Rock: tephrite, basanite

Territorial conservation

Level of protection: Registered geological localities suggested for protection
Protection of a geol. phenomenon: B - Geological phenomenon is the reason for a recommendation to the protection
Conflicts of interests: without conflicts

References

PALUSKA, Antonín & VESELÝ, Pavel (2010): Návrh na rozšíření chráněné oblasti Národní přírodní památky „Čertova zeď“ v severních Čechách (Český Dub-Osečná) a vytvoření chráněné oblasti „Velká Čertova zeď“.- 2. vulkanologický seminář odborné skupiny vulkanologie České geologické společnosti v Teplicích,Speciální publikace Regionálního muzea v Teplicích, str. 35-36.

Elaboration and Updating

Elaborated by: Gürtlerová Pavla, 07.02.12
Updated by: Gürtlerová Pavla 24.03.14, Gürtlerová Pavla 24.02.15, Kukal Zdeněk 25.09.17, Kukal Zdeněk 26.09.17

Citation

The database Significant geological localities of the Czech Republic: 3402 [online]. Prague: Czech Geological Survey, 1998 [cit. 2024-04-29]. Available from: http:// lokality.geology.cz/3402.

Location in map: