On the geology and fauna of the Ülgase member (Lowermost Tremadoc of North Estonia)

The Ülgase member consists of gray quartzaleurolits and sandstones. The lower and upper boundaries of the member are distinct, with an erosional surface and pebbles. Granulometrically the Ülgase rocks are different from the overlying and underlaying ones, and there are no intercalations of graptolitic shales as in the overlying Maardu member. The Ülgase member occurs in a limited area in North Estonia. The thickness of the member amounts to 7m. Obolus sp. п., Conotreta sp. п. and Schmidtites sp. п. that have recently been recorded from the Ülgase beds suggest the Early Tremadocian age of the member in question.