Borucice Formation

The Borucice Formation, also known in older literature as the Borucice Series, is a Jurassic (Middle-Late Toarcian) geologic formation that extends to nearly whole of Poland. This formation represents the last sequence of the lower Jurassic in Poland, recovering the depositional sequences IX and X, and may even recover lowermost parts of the first Middle Jurassic sequence. It represents mostly a series of alluvial (braided or meandering channel) depositional systems with subordinate intervals of deltaic deposits. Dinosaur Tracks are among the fossils that have been recovered from the formation. Most of the sediments of the Polish realm come from deltaic, fluvial and marine deposits. It mainly consists of light whitish-grey, fine grained sandstones interbedded by clay containing plant detritus and minute fragments of coal. It also has dark grey mudstones with marine lamellibranches and an Upper Lias microfauna. Its main equivalents are the Jurensismergel Formation of Germany, upper part of the Rya Formation (Southern Sweden)and the uppermost Sorthat Formation (Bornholm). There are also coeval abandoned informal units in Poland: Upper Lisiec beds (Czêstochowa region), or the Kamień Beds (Pomerania region).