Utwory czwartorzędowe okolic Hrubieszowa

Abstract

Na podstawie szczegółowych badań terenowych i laboratoryjnych - stosując metodę litostratygraficzną i badania gleb kopalnych a także bezwzględne datowania szczątków kostnych znalezionych w osadach czwartorzędowych okolic Hrubieszowa - wykonano próbę określenia ich stratygrafii. Wydzielono osady eoplejstoceńskie, mezo- i neoplejstoceńskie. Reprezentują je głównie lessy zróżnicowane facjalnie.

QUATERNARY DEPOSITS FROM THE VICINITIES OF HRUBIESZÓW

Two erosional-denudational planation surfaces were found beneath thick series of loesses on highlands 210-220 and 190-210 m a.s.l., respectively, in the vicinities of Hrubieszów. The lower planation surface, corresponding to the lower (III) horizon distinguished in the Lublin Upland by A. Jahn (1956), is overlain by pre-Glacial gravels presumably belonging to so-called Kozienice series (J. E. Mojski, 1964). It is incised by pre-Glacial river valleys with a system of fossil terraces built of pre-Glacial gravel-sandy and silty deposits of the Krasnystaw series (fig. 1-6).

In valleys, the deposits of the Krasnystaw series are overlain by Mesopleistocene silty clays and loess-like silty loams. The latter infill pre-Glacial valleys. On slopes of buried valleys and on highlands .the Mesopleistocene clays and loams are sometimes overlain by Cracow till or the oldest loess which is coeval with that glacial deposit. In buried valleys these Mesopleistocene deposits are truncated by erosional surface above which ·occur fluvial Sands from the Great Interglacial times. At places where terrain surface from these times was situated higher there are found fossil forest soils or denudational surfaces representing the base of overlying Neopleistocene deposits, i.e. older Middle-Polish and younger North-Polish loesses. Neopleistocene loesses are separated by Eemian Interglacial soil in more complete profiles. The older and younger loesses display intercalations of fossil soils and soil sediments of the interstadial range which are dividing them into lower-rank stratigraphic units.

In valleys of the Bug and Huczwa rivers there were found 3 raised terraces (the highest, Middle-Polish, and higher and lower North-Polish terraces) and 2 flood plain benches (higher, older Holocene, and lower, Recent).