The Great Rift Valley is a system of low areas inside a continent that stretches from north to south through Kenya. It is part of the Gregory Rift, the eastern part of the East African Rift, which begins in Tanzania to the south and extends north into Ethiopia. It was formed on the "Kenyan Dome," a bulge in the Earth's surface caused by the movement of three major tectonic plates: the Arabian, Nubian, and Somali plates. In the past, it was considered part of a larger "Great Rift Valley" that stretches from Mozambique to Syria. Most of the valley is located within the former Rift Valley Province.

The valley includes the Cherangani Hills and a series of volcanoes, some of which are still active. The climate is mild, with temperatures usually below 28 °C (82 °F). Most rainfall occurs during March–June and October–November. The Tugen Hills, located west of Lake Baringo, contain fossils preserved in lava flows from 14 to 4 million years ago. Remains of many hominids, early human ancestors, have been discovered in this area.

Features

The valley is bordered by steep slopes to the east and west. The valley floor has volcanoes, some of which are still active, and includes several lakes. Some of the soil in the area is called Andisols, which are fertile and formed from volcanic activity that happened not long ago.

Lake Turkana is located at the northern end of the Great Rift Valley in Kenya. There are also volcanoes near Lake Turkana. The Suguta Valley, also known as the Suguta Mud Flats, is a dry area of the Great Rift Valley directly south of Lake Turkana. The shield volcano Emuruangogolak crosses the valley to the south of Suguta. Further south, Mount Silali and Paka rise from the valley floor. Paka is a shield volcano with widespread geothermal activity. South of Paka are Mount Korosi, Lake Baringo, and Lake Bogoria. Menengai is a large shield volcano in the valley floor with a caldera that formed about 8,000 years ago. It overlooks Lake Nakuru to the south. This area also includes Lake Elementaita, Mount Kipipiri, and Lake Naivasha.

Hell's Gate National Park is located south of Lake Naivasha. In the early 1900s, Mount Longonot erupted, and ash from the eruption can still be found near Hell's Gate. Mount Longonot is a dormant stratovolcano located southeast of Lake Naivasha. Mount Suswa is a shield volcano between Narok and Nairobi. Lava flows from recent eruptions are still not covered by plants and may be no more than 100 years old. Lake Magadi is the southernmost rift valley lake in Kenya, although the northern end of Lake Natron in Tanzania extends into Kenya.

The Elgeyo escarpment is part of the western wall of the valley. The Kerio Valley lies between the Tugen Hills and the Elgeyo escarpment at an elevation of 1,000 meters (3,300 feet). There are large deposits of Fluorite in the Kerio Valley area. Further south, the Mau Escarpment is a steep natural cliff about 1,000 meters (3,300 feet) high, running along the western edge of the Great Rift Valley near Lake Naivasha. Further south, the Nguruman Escarpment is about 50 kilometers long and extends in a northwest direction. Its northern edge is approximately 120 kilometers (75 miles) southwest of Nairobi, while its southern edge is near the Tanzanian border, at the northwestern corner of Lake Natron. The Aberdare Range forms part of the eastern edge of the Great Rift Valley north of Nairobi. Mount Satima is at the northern end of the Aberdares and is the highest peak, while Mount Kinangop at the southern end is the second highest. The mountains form a ridge between these two peaks. The Ngong Hills are peaks in a ridge along the eastern side of the Great Rift Valley, located southwest of Nairobi.

Lakes

Kenya has 64 lakes, which is about 9.50% of all the lakes in Africa. Eight of these lakes are the main lakes in the Kenyan Rift Valley. From north to south, the lakes are named Lake Turkana, Lake Logipi, Lake Baringo, Lake Bogoria, Lake Nakuru, Lake Elmenteita, Lake Naivasha, and Lake Magadi. Of these eight lakes, only Baringo and Naivasha contain fresh water.

Lake Turkana, at the northern end of the rift, is 250 kilometers long, between 15 and 30 kilometers wide, and 125 meters deep. Most of the other lakes are shallow and not well drained, so they are alkaline. These lakes have water rich in blue-green algae, which support insect larvae, small crustaceans, and lesser flamingos. The larvae and crustaceans are food for fish and greater flamingos. Large groups of these birds affect the lake's sediments. Their numbers cause trampling of silts in some areas, while their feeding helps oxygenate the mud. Their nests can form irregular shapes on the lakeside as water levels change.

Trona, a type of mineral used to make sodium carbonate, has been mined at Lake Magadi for nearly 100 years. It produces about 250,000 metric tonnes each year. Other valuable minerals, such as rubies and pink sapphires, have been found near Lake Baringo. In 2004, over 2 kilograms of corundum were collected.

Three shallow, alkaline lakes and their surrounding areas form the Kenya Lake System: Lake Bogoria (10,700 hectares), Lake Nakuru (18,800 hectares), and Lake Elmenteita (2,534 hectares). This system has one of the most diverse bird populations in the world and is home to thirteen globally threatened bird species. It is an important nesting and breeding site for great white pelicans and the most important feeding area for lesser flamingos. The system also supports significant populations of black-necked grebe, African spoonbill, pied avocet, little grebe, yellow-billed stork, black-winged stilt, grey-headed gull, and gull-billed tern.

The Kenya Lake System is a key stop on the West Asian-East African Flyway, a path birds follow during migration from breeding areas in the north to wintering areas in Africa. The lands around the lakes have large numbers of black rhinos, Rothschild’s giraffes, greater kudus, lions, cheetahs, and wild dogs. The Kenya Lake System is surrounded by the steep escarpment of the Rift Valley, creating a striking landscape.

Other lakes include Lake Chew Bahir in the northeast, which is mainly in Ethiopia but sometimes extends into Kenya during the rainy season. Lake Kamnarok is another small lake.

Gallery

• Lake Baringo, August 1999
• Drawing by John Walter Gregory from his trip to East Africa in 1892–1893. "[Mount] Kenya from the Kapte Plains west of Machakos"
• The Great Rift Valley near Eldoret, Kenya, in the fall of 2006
• An adult purple heron with young birds on a nest at Lake Baringo
• An African fish eagle preparing to catch a fish in Lake Naivasha