The Golan Heights have distinct geographic boundaries. On the north, the Sa'ar Stream (a tributary of Nahal Hermon/Nahr Baniyas) generally divides the lighter-coloured limestone bedrock of Mount Hermon from the dark-coloured volcanic rocks of the Golan plateau. The western border of the plateau is truncated structurally by the Jordan Rift Valley, which falls down steeply into the Sea of Galilee (Lake Kinneret, Lake Tiberias). The southern border is lined by the Yarmouk River, which separates the plateau from the northern region of Jordan. Finally, the eastern edge of the Golan Heights is carved out by the Raqqad river (Wadi ar-Ruqqad), along which are stretching the areas still controlled by Syria.