NGORONGORO CRATER

The main feature of the Ngorongoro Conservation Authority is the Ngorongoro Crater, the world's largest inactive, intact, and unfilled volcanic caldera.^[9] The crater, which formed when a large volcano exploded and collapsed on itself two to three million years ago, is 610 metres (2,000 feet) deep and its floor covers 260 square kilometres (100 square miles).^[7][10] Estimates of the height of the original volcano range from 4,500 to 5,800 metres (14,800 to 19,000 feet) high.^[10][11][12] The elevation of the crater floor is 1,800 metres (5,900 feet) above sea level.^[1] The Crater was voted by Seven Natural Wonders ^[13] as one of the Seven Natural Wonders of Africa in Arusha, Tanzania in February 2013.^[14]

The crater highlands on the side facing the easterly trade winds receives 800 to 1,200 millimetres (31 to 47 inches) of rain a year and are covered largely in montane forest.^[9] The less-steep west wall receives only 400 to 600 millimetres (16 to 24 inches) and is grassland and bushland dotted with Euphorbia bussei (es) trees.^[9] The crater floor is mostly open grassland with two small wooded areas dominated byAcacia xanthophloea.^[9]

Lake Magadi

The Munge Stream drains Olmoti Crater to the north, and is the main water source draining into the seasonal salt lake in the center of the crater. This lake is known by two names: Makat as the Maasai called it, meaning salt; and Magadi.^[15] The Lerai Stream drains the humid forests to the south of the Crater, and it feeds the Lerai Forest on the crater floor - when there is enough rain, the Lerai drains into Lake Magadi as well. Extraction of water by lodges and NCA headquarters reduces the amount of water entering Lerai by around 25 percent.^[16]

The other major water source in the crater is the Ngoitokitok Spring, near the eastern crater wall. There is a picnic site here open to tourists and a huge swamp fed by the spring, and the area is inhabited by hippopotamus, elephants, lions, and many others. Many other small springs can be found around the crater's floor, and these are important water supplies for the animals and local Masaai, especially during times of drought.

Following the recommendations of the ad hoc committee of scientists convened after the year 2000 drought, an ecological burning program was implemented in the crater, which entails annual or biannual controlled burns of up to 20 percent of the grasslands.^[17] Maasai are now permitted to graze their cattle within the crater, but must enter and exit daily.^[8]