Chauda Horizon

(after Cape Chauda on the Kerch’ Peninsula), the lower Pleistocene of the Black Sea region. Established by the Russian geologist N. I. Andrusov (1889), the Chauda horizon is represented by sands, coquinas, conglomerates, and clays (layers up to 15–20 m thick) containing Didacna tschaudae, D. pseudocrassa, and the like, which were deposited in an isolated brackish basin. It is found on the Kerch’ and Taman’ peninsulas, along the Caucasian coast of the Black Sea (a terrace 100–110 m high) and the shores of the Sea of Marmara, and in the Dardanelles. The Chauda horizon corresponds to the Baku horizon of the Caspian region. The Chauda basin occupied the basins of the Black Sea and the Sea of Azov, which received the outflow from the Baku Sea through the Manych Valley. It discharged into the Sea of Marmara and the Aegean Sea with no back-flow.