A rift like no other
The Great Rift Valley is a long depression in the earth which runs down the eastern side of Africa. It extends from Syria in the Middle East, right down to Mozambique in south-eastern Africa.
The Great Rift is visible from outer space and looks like two parallel lines running down Africa.
It began forming around 20-25 million years ago when the earth’s crust weakened and began tearing apart. This created a jagged rift stretching thousands of kilometers down eastern Africa.
The tearing of the earth's plate caused many eruptions and earthquakes. Volcanic mountains formed either side of the rift and the valley floor sank lower to form wide flat plains.
A huge basin for wildlife
The Ngorongoro is one of the many extinct volcanoes left over from when the Rift formed millions of years ago. This volcano collapsed inwards, leaving behind an enormous crater, known as a ‘caldera’. The basin is now home to rich grasslands and an almost continuous supply of water.
Today, this huge geological feature provides a unique landscape of mountains and escarpments, valleys and lakes. For example, at Lake Naivasha in Kenya, sheer cliffs rise 1900km high. In certain places, the valley floor of the Rift is nearly 100km wide.
The Rift's unique landscapes provide some of the most famous habitats for wildlife on the continent. Tanzania is home to two of these – the plains of the Serengeti and the Ngorongoro Crater (see Map).