Commune: Świerzawa (pow. złotoryjski, woj. dolnośląskie)
Framework element or context represented:
Permian volcanism.
Primary geological/geomorphological interest:
The Permian volcanism, columnar structure within rhyolite.
Comparative assessment justification:
Extrusion of rhyolitic lava with well developed columnar structure.
Protection status and accessibility:
The outcrop Organy Wielislawskie is a monument of inanimate nature established in 1965.
Character of site: Abandoned quarry.
Area: ca 0.5 ha
Altitude: 280-330 m a.s.l.
Lithology: other igneous rocks, other metamorphic rocks, sandstones
Discipline: Geomorphology, Petrography
Process Age: *all periods
Bedrock Age: Permian, Devonian, Silurian, Ordovician, *all periods
Description of primary interest:
The abandoned quarry on the slope of Wielislawka Mt. in the Kaczawa river valley is an excellent outcrop of the Permian (the middle part of the New Red Sandstone) alkaline rhyolites and the schists (Ordovician, Silurian, Devonian) of the metamorphic massif of the Kaczawskie Mts. Petrographically, the rock, of a characteristic brownish-reddish colour, consists of quartzite and plagioclase rich matrix with phenocrystals of quartz, biotite and feldspar. It has a very unusual, for this type of rock, columnar structure, due to which the outcrop resembles a gigantic organ or a fan. The diameter of the columns is normally 20-30 centimetres and only sometimes exceeds 50 centimetres. The majority of the columns are tetra- and rather pentagonal and rarely tri- and hexagonal. The fan-like complex of the columns as well as the system of joints, perpendicular to the cooling surface, indicates origin of this formation, a dome shaped extrusion of rhyolitic lava.
Literature:
BOBIŃSKI W., GAWLIKOWSKA E., KŁONOWSKI M. 1999 - Important geosites of the Polish Sudetes. Pol. Geol. Inst., Spec. Papers, 2: 19-25. GROCHOLSKI A. & JERZMAŃSKI J. 1975 — Palaeovolcanic occurence in the Lower Silesia, in the light of nature protection (English sum.). Ochrona Przyrody, 40: 291-349. JERZMAŃSKI J. 1956 — Porfir wzgórza Wielislawka w Górach Kaczawskich (Polish only). Prz. Geol, 4: 174-175. KOZŁOWSKI S. 1963 - Geology of the Permian volcanism in the central part of the Sudetes Basin (English sum.). Kom. Nauk Geol. PAN, Prace Geol. 14. KOZŁOWSKI S., PARACHONIAK W. 1967 — Permian volcanism in the North Sudetic depresion (English sum.). Prac. Muz. Ziemi, 11: 191-221.