Ngorongoro Crater

The area became a UNESCO World Heritage Site in 1979. The area is part of the Serengeti ecosystem, and to the north-west, it adjoins the Serengeti National Park and is contiguous with the southern Serengeti plains, these plains also extend to the north into unprotected Loliondo division and are kept open to wildlife through trans-human pastoralism practiced by Maasai. The south and west of the area are volcanic highlands, including the famous Ngorongoro Crater and the lesser known Empakai. The southern and eastern boundaries are approximately defined by the rim of the Great Rift Valley wall, wich also prevents animal migration in these directions. The annual ungulate migration passes through the NCA, with wildebeest and zebra moving south into the area in December and moving north in June.

This movement changes seasonally with the rains, but the migration will traverse almost the entire plains in search of food. The NCA has a healthy resident population of most species of wildlife, in particular the Ndutu Lake area to the west has strong cheetah and lion populations. A population of approximately 25,000 large animals, largely ungulates along with reputedly the highest density of mammalian predators in Africa, lives in the crater. These include the black rhinoceros, whose local population declined from about 108 in 1964-66 to between 11-14 in 1995, and the hippopotamus, which is very uncommon in the area. There also are many other ungulates: the wildebeest (7,000 estimated in 1994), the zebra (4,000), the eland, and Grant's and Thomson's gazelles (3,000).

The crater has dense population of lions, leopards, elephants, mountain reedbuck, and buffalo. The main feature of the NCA is the Ngorongoro Crater, which is the world's largest unbroken, unflooded volcanic caldera. The Crater, which formed when a giant volcano exploded and collapsed on itself some two to three million years ago, is 610 m (2,001 ft) deep and its floor covers 260 km² (102 square miles). Estimates of the height of the original volcano range from fifteen to nineteen thousand feet (4500 to 5800 metres) high.

The conservation area also protects Olduvai Gorge, situated in the plains area. It is considered the seat of humanity after the discovery of the earliest known specimens of the human genus, Homo habilis as well as early homonids, Paranthropus boisei. The Olduvai Gorge or Oldupai Gorge is a steep-sided ravine in the Great Rift Valley, which stretches along eastern Africa. Olduvai is in the eastern Serengeti Plains in northern Tanzania and is about thirty miles long.

It lies in the rain shadow of the Ngorongoro highlands and is the driest part of the region. The gorge is named after the Maasai word for the wild sisal plant, Sansevieria ehrenbergii, commonly called Oldupaai. It is one of the most important prehistoric sites in the world and research there has been instrumental in furthering understanding of early human evolution. Excavation work there was pioneered by Mary and Louis Leakey in the 1950s and is continued today by their family.

Some believe that millions of years ago, the site was that of a large lake, the shores of which were covered with successive deposits of volcanic ash. Around 500,000 years ago seismic activity diverted a nearby stream which began to cut down into the sediments, revealing seven main layers in the walls of the gorge.