The Lebanon mountains rise steeply parallel to the Mediterranean coast and form a ridge of limestone and sandstone that runs for most of the country's length. The mountain range varies in width between and ; it is carved by narrow and deep gorges. The Lebanon mountains peak at above sea level in Qurnat as Sawda' in North Lebanon and gradually slope to the south before rising again to a height of in Mount Sannine. The Beqaa valley sits between the Lebanon mountains in the west and the Anti-Lebanon range in the east; it is a part of the Great Rift Valley system. The valley is long and wide, its fertile soil is formed by alluvial deposits. The Anti-Lebanon range runs parallel to the Lebanon mountains, its highest peak is in Mount Hermon at .