Europe and Asia are separated by two mountain ranges - the Ural Mountains and the Caucasus Mountains. The Ural Mountains run from north to south of Western Russia, from the Arctic Ocean to the Ural River and the northwestern part of Kazakhstan. The Caucasus Mountains run through parts of Russia, Azerbaijan, Armenia, Georgia, and Turkey, and form a natural boundary between the two continents to the south of the Ural Mountains. It's worth noting that the boundary between Asia and Europe is largely defined by geography and cultural convention, rather than a strict geological or physical separation.