Stratigraphy and facials development of Middle and Upper Ordovician deposits in the Łeba Elevation (NW Poland)

A description is here given of the lithological characters of the Middle and Upper Ordovician deposits on the Łeba Elevation representing the western part of the Peribaltic Syneclise. Three llthostratigraphic formation B and one member connected with the central formation have been differentiated. Six biostratigraphic zones and two informal biostratigraphic units. have been differentiated on the basis of fossil assemblages varying with the lithofacies. In the light of the currently accepted division of the Ordovician into chronostratigraphic units the presence has been documented of Llanvirnian. Llandeilian, Caradocian and Ashgillian deposits. The facial and paleontological analyses reliably indicate the sedimentary conditions of the particular formations and the assignment of the area under investigation to the outermost zone of the Ordovician Balto-Scandian basin, the so called "Scania-Łeba" zone. Out of the sixty graptolite species and subspecies identified by the writer and belonging to 17 genera, a description has been made of stratigraphically important forms, so far not reported from Poland or interesting from the taxonomic point of view.