Caspian Depression

The Caspian Depression is a low-lying flatland region that lies at the northern end of the Caspian Sea. The depression lies at the southern end of the Ryn Desert, and is in both Kazakhstan and Russia. The Volga River flows through this region, and is the largest river flowing into the Caspian Sea, which is the largest enclosed body of water on earth. The deltas of the Ural and Volga Rivers are characterized by extensive wetlands. The North Caspian depression is part of the continental or semi-arid desert biome.

Much of the Caspian Depression is below sea-level, consisting of large areas of marshlands in the eastern region. The two largest cities in the depression are Atyrau in Kazakstan, and Astrakhan in Russia. It is one of the largest flat lowland areas in Central Asia, covering approximately 200,000 square km (77,220 square miles). The area is very rich in underground oil and gas reserves. Many geologists believe the Caspian Sea and the depression were formed by tectonic forces. Some of them also believe that the North Caspian depression became separated from the open ocean in ancient times to form an enormous salt lake.

The Russian name for the depression is prikaspiyskaya nizmennost'.

References

The Caspian Environment Programme - http://www.caspianenvironment.org/caspian.htm

Evaporites of North Border of North Caspian Depression - Internet Geology News Letter No. 178, January 13, 2003