 The eastern portion of the Great Escarpment (the Drakensberg) goes as far north as Tzaneen at approximately the 22° S parallel, from there it veers west to Potgietersrust, where it is known as the Strydpoort Mountains.The absence of the Great Escarpment for approximately to the north of Tzaneen (to reappear on the border between Zimbabwe and Mozambique in the Chimanimani Mountains), is due to a failed westerly branch of the main rift that caused Antarctica to start drifting away from southern Africa during the breakup of Gondwana about 150 million years ago.The lower Limpopo River and Save River drain into the Indian Ocean through what remains of this relict incipient rift valley, which now forms part of the South African Lowveld.