Przekrój geologiczny czwartorzędu okolic Rawy Mazowieckiej

Abstract

GEOLOGICAL SECTION OF QUATERNARY IN REGION OF RAWA MAZOWIECKAThe region of Rawa Mazowiecka is a morainic pIain of the Central Polish gIaciation. It is situated in the basin of the Rawka creek, a tributary of the Bzura river. Bore holes and mapping, intended for the Geological Map prepared by the Geological Institute, supplied the following data on the Quaternary stratigraphy of the area under discussion:The substratum of the Quaternary deposits consists of the evened surface of the Upper Jurassic of the Pomorze-Kujawy arc and, eastwards from Rawa, of Tertiary sediments. The oldest Quaternary is represented by sands and gravels on which lies boulder clay of the Southern Polish glaciation. This latter deposit is often divided, into two horizons; sometimes it is underlain by a bed of crystalline gravels. On top of this boulder clay lie varves clays, representing an index series in the stratigraphy of the Quaternary deposits of the discussed region. The deposits of the Great Interglacial, of considerable thickness, show but scanty plant detritus. They are built chiefly of finegrained sands and silts. The superimposed boulder clay of the Middle Polish glaciation consists of three, horizons the lowest of which is the facially most separated. It has proved difficult to link the range of the moraines of the individual stadials of the Central Polish glaciation with their corresponding boulder clay horizons. The Central Polish glaciation is the last m leave glacial accumulation in this region. The subsequent interglacial and the Baltic glaciation are chiefly distinguished by their marked influence on the shaping of valleys, and are characterized by deposits connected with the formation of these valleys.