Notes on the Upper Ordovician and Lower Silurian of the Tapa district, Estonia

The Upper Ordovician Saunja (FIa), Vormsi (FIb), Pirgu (FIc), and Porkuni (F2; in this paper included in the Ordovician) stages and the Lower Silurian Juuru (G1) stage are briefly characterized lithologically and faunistically according to the writer's field observations in the Tapa district. A stratigraphic column of the Lower Silurian in central Estonia up to the Adavere (H) stage is republished, somewhat modified, after Elsa Rosenstein (1943). A correlation of the lowermost Silurian between Estonia and Norway is suggested, whereby the supposedly considerable hiatus between the Porkuni and Juuru stages is much diminished.