Commune: Puck (pow. pucki, woj. pomorskie) , Puck (pow. pucki, woj. pomorskie)
Framework element or context represented:
Cave within the Late Pleistocene sandstones of the Mid-European Lowlands.
Primary geological/geomorphological interest:
Forms of recent lithification and denudation – cave.
Comparative assessment justification:
The most illustrative example of Pleistocene lithification and subsequent selective denudation in the Central Europe.
Protection status and accessibility:
Monument of nature since 1955, accessible for public (show cave).
Character of site: Cave and outcrop.
Area: 1 ha
Altitude: 60 m a.s.l.
Lithology: sandstones
Discipline: Geomorphology, Petrography
Process Age: Pleistocene, *all periods
Bedrock Age: Quaternary, *all periods
Description of primary interest:
Horizontal cave 61 m long, situated in the lowermost part of the stream valley slope and formed in sandstones. The sandstones represent Late Pleistocene sands, deposited during last glaciation (Vistulian) and cemented with calcite. Three main hypotheses of calcification have been taken into account: a) subglacial water degasing (and carbon dioxide evaporation) during last ice-sheet deterioration; b) calcite precipitation from water diffusing (circulating) within the sands during Holocene, almost recently (biogenic stimulation of the calcite precipitation is not excluded); c) complex sequence of hydrological, geological and geomorphological processes. Calcareous sandstones form harden bodies varying in size and shape within loose sands. The most typical and characteristic bodies represent horizontal sheet-like forms (blankest, thin lenses) and vertical collumnar forms as well as combinations of the both ones. The external part of the Cave in Mechowo is formed just in the complex form, what is expressed by picturesque natural colonnade in its entrance. It formed due to selective weathering (also karstification) and erosion (fluvial erosion and transport related to stream flow) of such a sandstone body. The internal parts of the cave consist of low and wide chamber located just behind the colonnade and low, gradually narrowed passage. The chamber and passage developed in weaker but more homogenously lithified rocks owing to natural processes and human activity since the discovering of the cave in 1818 (the cave was “restored” several times in 19th and 20th centuries). In the cave passage calcite flowstones have been forming due to water percolation trough the sandstones.
Literature:
BARYŁA J., URBAN J., ZAGÓRSKI S. 1998–Jaskinie Niżu Polskiego (Polish only). Pol. Tow. Przyj. Nauk o Ziemi, Warszawa, pp. 53. CONWENTZ H. 1910–Beiträge zur Naturdenkmalpflege. Bd. 1. Gebrüder Borntraeger. Berlin, pp. XI, 510. DROZDOWSKI E. 1991–Sandstones and conglomerates formed by precipitation of CaCO3 under stagnant ice sheet. Bull. Pol. Acad. Sci., Ser. Earth Sci., 39: 253-266. KAMIŃSKI J., ZAŁOBA M. 1985–The origin and the age of Quaternary sandstones near Łódź (English sum.). Acta Geogr. Lodz. 50: 29-50. KOWALSKI K. 1953–Jaskinie Pomorza (Polish only). In: Kowalski K., Les cavernes de la Pologne, PWN, Warszawa: 157-164. PIĄTKOWSKI J. 1966–Czwartorzędowy piaskowiec i Jaskinia w Mechowie koło Pucka (Polish only). In: Przew. wycieczek ter. w trzecim dniu Symp. Sedyment. Pol. Tow. Geol., 24.09.1966. Pol. Tow. Geol., Gdynia: 2-4. SZUKALSKI J. 1961–Rzadka osobliwość skalna na Pobrzeżu Kaszubskim (Polish only). Geogr. w Szkole 14: 100-102. SZUKALSKI J. 1962–Geomorphological relations in the suburban zone of the Tripple Town (Gdańsk-Sopot-Gdynia) (English sum.). Zesz. Geogr. WSP. w Gdańsku 4: 121-183. SZUKALSKI J. 1984–Jaskinie na Kaszubach (Polish only). Pomerania 9: 31-32. URBAN J. 1999–The caves in Pleistocene sandstones of the Polish Lowlands. In: Tulucan T. (ed.) Proc. of the 7th Intern. Symp. for Pseudokarst, Arad-Moneasa, Romania, 6-10 Oct.1999, Arad: 22-27. URBAN J. 2000–The sandstone tors and caves in the Polish Lowlands (English sum.). Przegl. Geol. 48, 5: 409-411. URBAN J. 2004–Caves and karst sites of Poland as a contribution to geological heritage of Central Europe. Pol. Geol. Inst., Special Papers 13: 89-96.