Orographically the backbone of the country is the mountain chain which forms the eastern escarpment of the continental plateau. It does not present a uniformly abrupt descent to the plains, but in places, as in the lower Zambezi district, slopes gradually to the coast. The Lebombo Mountains, behind Delagoa Bay, nowhere exceed in height. The Manica Plateau, farther north between the Save and Zambezi rivers, is higher, rising towards the Eastern Highlands along the border with Zimbabwe. Monte Binga (), on the border with Zimbabwe, is Mozambique's highest peak. Mount Gorongosa () lies north-east of the Manica Plateau, and is, like it, of granitic formation. Gorongosa, rising isolated with precipitous outer slopes, has been likened in its aspect to a frowning citadel. East of Gorongosa a graben valley extends from the Zambezi to Pungwe Bay, the southern extension of the African Rift Valley. The Cheringoma Plateau lies east of the graben, sloping gently towards the coast.