Caucasus Mountains, a Eurasian mountain system between the Black and Caspian seas. Some geographers consider it to be made up of two ranges, the Greater and the Lesser Caucasus. Others consider the Lesser Caucasus Mountains to be a separate system. This article describes both ranges.

The Greater Caucasus Mountainsare shared by Russia, Georgia, and Azerbaijan. The range extends southeast for about 700 miles (1,125 km) from near Novorossiysk on the Black Sea to the Apsheron Peninsula on the Caspian Sea. Geographers often consider the Greater Caucasus Mountains to be a boundary between Europe and Asia. The mountains are extremely rugged. A number of peaks exceed elevations of 15,000 feet (4,570 m); Elbrus, which rises to 18,510 feet (5,642 m), is Europe's highest peak. Because the range is such a formidable barrier, no railways and only a few roads cross the main part of the range. The range also forms a climatic barrier, shielding the southern slopes from the bitter winter weather that grips Russia to the north.

The Greater Caucasus Mountains have extensive mineral resources. Oil and gas production, especially near Baku, has long been important. At Chiatura manganese is mined from one of the world's largest deposits. There is also some mining of coal, lead, and zinc.

The Lesser Caucasus Mountainsare shared by Georgia, Armenia, and Azerbaijan. They lie south of the Greater Caucasus and run parallel to that range. The Lesser Caucasus Mountains extend about 350 miles (565 km) from near the mouth of the Rioni River on the Black Sea to near Azerbaijan's border with Iran. The range is less rugged than the Greater Caucasus. Peaks rarely exceed 10,000 feet (3,050 m).