Commune: Sękowa (pow. gorlicki, woj. małopolskie)
Framework element or context represented:
Stratygraphy and Cretaceous biota of flysh Magura Nappe.
Primary geological/geomorphological interest:
Complex of Inoceramian Beds rich in fauna.
Comparative assessment justification:
The site of Inoceramian Beds as the deposits of historical investigations and controversy.
Protection status and accessibility:
Protected as the nature monument (1998).
Character of site: Natural outcrop.
Area: 1.8 ha
Altitude: 340 m a.s.l.
Lithology: sandstones, shales
Discipline: Palaeobiology, Palaeoenvironment, Stratigraphy of Phanerozoic, History of geology
Process Age: Holocene, *all periods
Bedrock Age: Paleogene, Cretaceous, *all periods
Description of primary interest:
The site is localized in the bottom and both banks of the small Sękówka River in Ropica Górna, and extends for about 220 m downstream and some 150 m upstream of the bridge in this locality (protected now only 250 m). There occurs a thick complex of the Inoceramian Beds (Ropianka Formation) of the Magura Nappe, developed as alternating medium- and thin-bedded sandstones and shales. The site is actually composed of a range of outcrops of various sizes, from single meters to some tens of meters. In the lower part of the site the complex of steeply dipping layers strikes generally N-S and is of the subsequent character, consistent with the direction of the river bed. Individual layers of the sandstones build a number of rocky ribs; upstream of the bridge the rocks are normally positioned with the general bearings 110/65/SW. The sandstones of the strata in question reveal very clearly sets of sequences of the turbidite sedimentary structures, with particularly distinct convolute lamination, along which they disintegrate. The inventory of bioglyphes and mechanoglyphes is very rich, and the sandstones are intersected by characteristic small veins of white calcite. In the upper part of the outcrop dominate ash-grey and ash-grey-greenish shales with subordinate thin-bedded sandstones. They contain also horizons of variegated shales, i.e. red and green ones, with a thickness of up to several meters. The strata of this outcrop contain the fauna of inocerams and rich microfauna of foraminifers, mainly agglutining and calcareous-planktonic. From this very region come the pioneering works of J. Grzybowski from the turn of the 19th century on foraminifer microfauna of the Carpathian strata.
Literature:
GONERA M., ALEXANDROWICZ Z. & URBAN J. 2000–Protected areas and objects. In: Alexandrowicz Z. & Poprawa D. (reds) Geodiversity coservation of the Polish Carpathians. (English sum.). Państw. Inst. Geol., Warszawa: 98-108. GRZYBOWSKI J. 1901–Die microfauna der Karpathenbildungen. III. Die Foraminiferen der Inoceramenschichten von Gorlice. (Polish only). Rozpr. i Spr. Wydz. Mat.-Przyr. AU, Ser. III B, 1: 219-298. JURKIEWICZ H. & KARNKOWSKI P. 1959–Age of Inoceramus beds in the Magura nappe. (English sum.). Acta Geol. Pol., 9/1: 17-54. KOTLARCZYK J. 1978–Stratigraphy of the Ropianka Formation or of Inoceramian beds in the Skole Unit of the Flysh Carpathians. (English sum.). Prace Geol. PAN, 108: 1-82. OLSZEWSKA B. 1984–A paleoecological interpretation of the Cretaceous and Paleogene Foraminifers of the Polish Outer Carpathians. (English sum.). Biul. Państw. Inst. Geol., 346: 7-62. ŚWIDZIŃSKI H. 1973–The geological structure of the region Ropica – Siary Górne. (English sum.). Prace Geol. PAN, 80: 63-76. UHLIG V. 1885–Ergebnisse geologischer Aufnahmen in den westgalizischen Karpathen. Theil. I. Die sandsteinzone zwischen dem penninischen Klippenzuge und dem Noedrande. Jahrbuch d. Geol. Reichsanstalt., 38: 83-264, Vien. WALTER H. & DUNIKOWSKI E. 1882/1883–Geologiczna budowa naftonośnego obszaru zachodnio-galicyjskiego Karpat. (Polish only). Kosmos, 7: 263-302, 8: 309-334. WĘCŁAWIK S. 1969–The geological structure of the Magura Nappe between Uście Gorlickie and Tylicz. (English sum.). Prace Geol. PAN, 59: 1-96.