Commune: Bolesław (pow. olkuski, woj. małopolskie)
Framework element or context represented:
Calcareous tufa.
Primary geological/geomorphological interest:
Travertine dome.
Comparative assessment justification:
One of several sites of Quaternary tufa and travertines distinguished after as a quite specific form.
Protection status and accessibility:
Nature monument.
Character of site: Natural outcrop.
Area: c. 1 ha
Altitude: 304 m a.s.l.
Lithology: sands, other sedimentary rocks
Discipline: Geomorphology, Palaeoenvironment, Stratigraphy of Quaternary
Process Age: Holocene, *all periods
Bedrock Age: Holocene, *all periods
Description of primary interest:
Exposures of calcareous sediments are located within and immediately around a travertine dome. The dome was found at the northern margin of Laski village near Olkusz at south border of the Błędowska Desert in the valley of Biała River. The mound is underlying by Pleistocene fluvioglacial and aeolian sands having thickness up to 10 meters. The travertines developed within zone of springs. The dome itself comprises hard, porous travertines with layers, pockets, lenses of nests filled with unconsolidated, mostly granular calcareous tufa. A small cave (8 meters long) is developed within the mound. The walls and roof of the cave is composed from travertines while the floor is formed within cementated fluvioglacial and sands. Travertines and calcareous tufa exposed in Laski village shows rather poorly diversified molluscs assemblage. Mollusc assemblages identified in the profiles of calcareous tufa indicate the open-country, locally wet environment (presumably, small, ephemeral lakes) whereas shade-loving and open-country species are rare. Fauna composition, particularly the presence of quite common shells of thermophobic forms, points to Late Glacial and Lower Holocene age of sediments. Radiocarbon datings of travertines from the dome and from other sources gave the age interval between 11,500±120 (ISGB-655) and 5,350±80 (ISGB-576) years B.P. Thus, the dome developed in Young Dryas, Lower Holocene and in the lowermost part of Middle Holocene. Such age interpretation corresponds very well to the results of malacological analysis.
Literature:
GRADZIŃSKI M., SZULC J., MOTYKA J., STWORZEWICZ E. TYC A. 2001–Travertine mound and cave in a village of Laski, Silesian-Cracow Upland. Ann. Soc. Geol. Pol.; 71: 115-123. GRADZIŃSKI M., MOTYKA J., SZULC J. TYC A. 2001–Stanowisko martwicy i jaskinia w Laskach (Polish only). Mat. 33 Symp. Spel.: 26-31. TYC A. 2001–Research and protection of the travertine mound and the cave in Laski, the Silesian Upland. Slovensky Kras; 39: 161-169. TYC. A. 2001–Unikatowe stanowisko czwartorzędowych trawertynów w Laskach na południowym obrzeżeniu Pustyni Błędowskiej (Polish only). Mat. Konf. „Badania naukowe w południowej części Wyżyny Krakwsko-Częstochowskiej” Referaty, postery, sesje terenowe: 115-117. TYC A. POLONUS A. 1998–Schronisko w ostańcu martwicy wapiennej w Laskach (Polish only). Jaskinie; 6: 6-7.