Luangwa River ago, there was no way out and the Luangwa Rift filled with a Rift Valley Lake called the Madumabisa Lake, which rivalled Lake Malawi in size. The water of the lake overflowed in a river to the south-west, towards what is now the Kalahari, where it combined with the Okavango, Upper Zambezi, Cuando and Kafue rivers, emptying into the Limpopo River and flowing to the Indian Ocean. Several geological events combined to produce the current river systems. Faulting produced another graben just to the south of the Luangwa Rift, and running east-west: the Zambezi Rift Valley and the Chicoa Trough.
Zambezi tributary of the Shire River in the East African Rift's southern extension through Malawi eroded a deep valley on its western escarpment. At the rate of a few cm per year, this river, the Middle Zambezi, started cutting back the bed of its river towards the west, aided by grabens (rift valleys) forming along its course in an east-west axis. As it did so it captured a number of south-flowing rivers such as the Luangwa and Kafue. Eventually the large lake trapped at Makgadikgadi (or a tributary of it) was captured by the Middle Zambezi cutting back towards it, and