Commune: Besko (pow. sanocki, woj. podkarpackie)
Framework element or context represented:
Lithostratigraphy, tectonics, sedimentology.
Primary geological/geomorphological interest:
Sequence of the Oligocene deposits of Silesian Unit, tectonic and sedimentary structures, gorge river valley.
Comparative assessment justification:
The most representative sequence of the Oligocene deposits, tectonic and sedimentary structures.
Protection status and accessibility:
The application of geological reserve is preparing.
Character of site: Natural outcrops.
Area: 15 ha
Altitude: 300-350 m a.s.l.
Lithology: sandstones, limestones, shales
Discipline: Palaeobiology, Geomorphology, Palaeoenvironment, Stratigraphy of Phanerozoic, Tectonics
Process Age: Neogene, *all periods
Bedrock Age: Paleogene, *all periods
Description of primary interest:
The profiles of flysch deposits can be observed in two localities upstream and downstream of the Sieniawa reservoir. The first profile represents the boundary complex between Menilite Shale and Lower Krosno Beds. The sequence begins with dark shales with grey sandstones (boundary complex) passing upward into thick-bedded calcareous sandstones with subordinate intercalations of the marly shales (Lower Krosno Beds). Upstream the layers of white pelagic limestones occur (Jasło Shales). The Jasło Shales form a unique and very important correlation horizon. The second locality is situated upstream of the Sieniawa reservoir. It begins with yellowish thick-bedded sandstones of Lower Krosno Beds. About 200 m upstream is situated the 40 meters high outcrop of the Mszanka Sandstones with layer of submarine slide in its lower part. These sandstones passing into Menilite Beds forming the larges natural exposure in Polish Carpathians. The 80 m high rocky wall is composed of dark brown and rusty shales. The several tectonic structures connected with Rudawka Rymanowska anticline can be observed. On the left side of the exposure several intercalations of black cherts are visible. The exposures described above are particularly valuable for sedimentological studies. Different types of depositional structures can be observed. Moreover the picturesque river gorge is another value of this locality.
Literature:
ALEXANDROWICZ Z. 1987–Rezerwaty i pomniki przyrody województwa krośnieńskiego (Polish only). Stud. Naturae B-32: 23-72. ALEXANDROWICZ Z., POPRAWA D., RĄCZKOWSKI W. 1999–Stratotypes and other important geosites of the Polish Carpathians. Pol. Geol. Inst., Spec. Papers, 2: 33-46. BIEŃKOWSKA M. 2004-Taphonomy of ichthyofauna from an oligocene sequence (Tylawa Limestones horizon) of the Outher Carpathians Poland. Geol Quarterly, 48 (2): 181-192. DŻUŁYŃSKI S. 1996–Erosional and deformational structures in single sedimentary beds: a genetic commentary. Ann. Soc. Geol. Pol. 66: 101-189. HACZEWSKI G. 1989–Coccolith limestone horizons in the Menilite-Krosno Series (Oligocene, Carpathians): identification, correlation, and origin (English sum.). Ann. Soc. Geol. Pol. 59: 435-523. ŚLĄCZKA A. 1973–Wycieczka 4,6 [W:] Żytko [red.] Przewodnik geologiczny po wschodnich Karpatach fliszowych (Polish only). ŚLĄCZKA A., KAMINSKI M. 1998–A Giudebook to Excursion in the Polish Flysch Carpathians; Stops 36-38: 107-115. Special Publ. 6. Grzybowski Foundation. Kraków. WDOWIARZ S. 1968–Silesian and Sub-Silesian Units north from Krosno. [in:] Książkiewicz M. [ed.] Geology of the Polish Flysch Carpathians. Gude to excursion C44 IGC Prague: 58-65.