Why are the Black Sea coasts steep and mountainous in the east and south?

The steep and mountainous nature of the Black Sea's eastern and southern coasts is primarily the result of the region's complex geologic history and the rise of major mountain ranges surrounding the basin.12

During the Miocene Epoch, the uplift of several significant mountain systems—including the Pontic Mountains in the south and the Caucasus ranges in the east—created the rugged, precipitous terrain that defines these shorelines today. These mountains are part of a broader tectonic mosaic formed by the Alpine orogeny, a process driven by the northward compression of Africa into Europe that destroyed the ancient Tethys Sea.123

In the east, the Black Sea is confined by spurs of the Greater and Lesser Caucasus, which are separated by the Kolkhida lowland. In the south, the Pontic Mountains run directly along the coast, contributing to the steep relief. This tectonic activity remains ongoing, as evidenced by the region's continued seismic disturbances and earthquakes.123