 The lake lies in a valley formed by the opening of the East African Rift, where the African tectonic plate is being split into two pieces.This is called a divergent plate tectonics boundary.Malawi has typically been estimated to be 1–2 million years old (mya), but more recent evidence points to a considerably older lake with a basin that started to form about 8.6 mya and deep-water condition first appeared 4.5 mya.