The Great Rift Valley

The Great Rift Valley is a vast break in the Earth’s surface that runs for 6 400 kilometers, from Jordan in southwest Asia to the coast of the Indian Ocean in Mozambique, Africa. The valley is around 50 kilometres wide in most places, but at its widest section, in the Danakil Desert. It reaches 480 kilometers! The steep walls of the valley, called escarpments, rise about 900 metres above the valley floor… in some places, even higher! The walls of the Mau Escarpment in Kenya are 2 700 metres high.

How did this long, deep rip in the Earth occur? Around 30 million years ago, forces from the swirling magma under the Earth’s surface caused cracks to form in the Earth’s crust. These cracks are called faults. A block of crust between two faults began to drop, or subside. This left a long trench, called a rift valley.

Today, the Great Rift Valley is still growing! In the next few million years, eastern Africa may break off completely forming a new landmass. All this activity in the Earth’s crust allows magma to seep upward, sometimes breaking through the surface as a volcano. Volcanoes are dotted along the Great Rift Valley; the two tallest are Mount Kenya and Mount Kilimanjaro. Other features of the Valley include open savannah, forested mountains, grasslands, rivers, and huge, deep lakes.

This varied physical landscape provides habitats for more species of wildlife than anywhere else in Africa — the Great Rift Valley is Africa’s most biodiverse region. Lions, leopards, and cheetahs roam the savannahs. In the forests, chimpanzees and monkeys swing in the bamboo and mahogany trees. Crocodiles patrol the lakes and rivers where their favourite prey, flamingos, gather. Flamingos feed on blue-green algae that thrive in the Rift Valley’s salty lakes: like Lake Bogoria in Kenya, and Lake Natron in Tanzania.

Humans and their ancestors have lived in the Great Rift Valley region for millions of years. Lying between the Valley’s layers of ancient dirt and rocks are well-preserved fossils and bones. In 1974, the female skeleton of an early human species was discovered in Ethiopia. The fossil expert, or paleontologist, who discovered her was Donald Johanson. Johanson used volcanic ash nearby to calculate the skeleton’s age: 3.2 million years!

He nicknamed her Lucy. Today, the Great Rift Valley supports some of the few remaining full-time hunter-gatherer communities on Earth. The Hadza people live in the Tanzanian section of the Valley, where they hunt baboons, forage for roots and berries, and gather honey. Others living along the Valley make their living from fishing. Like here, at Lake Naivasha in Kenya, where fishers catch black bass and tilapia.

Tourism, too, is a large industry in many regions of the Valley. Visitors hosted in safari lodges and luxury hotels can spend their days wildlife watching, boat riding, or water skiing. But the natural environment that supports human activity in the Valley is under threat. Logging is shrinking forest areas and destroying wildlife habitats. Harmful chemicals from mining are polluting some lakes, while others suffer overfishing, which threatens their natural ecosystems.

Many local and international groups are working in the region to ensure the Great Rift Valley’s extraordinary history, scenery, and wildlife are preserved for generations to come.