Ngorongoro Crater lies along the western rim of the East African Rift Valley, a 6500-kilometer long fault that runs from Jordan in the north to Mozambique in the south. Clearly seen from space, this fault looks like an immense gash in the earth. Here, two of the earth's tectonic plates meet and grind against each other, moving in separate directions. This movement built up stress in the earth's crust, until one day, eons ago, the earth shook and the eastern side of the fault dropped hundreds of feet, creating the Rift Valley. On the west side of the fault a 2800-meter high escarpment looms over the valley, aside which sits Ngorongoro Crater National Park. The road between the two parks climbs the face of the escarpment and runs along the narrow crater rim, affording spectacular views, with the sheer drop into the East African Rift Valley and Lake Manyara on one side and the equally steep drop into the volcano crater on the other. The Crater itself, which covers 260 square miles and is 15 miles across, comprises Ngorongoro National Park. Over time a shallow lake has formed on the crater floor, which is 600 meters below the rim. The depth of the crater beneath the sheer walls, along with the lake that never dries up, has created a microenvironment that allows the animals to stay here year-round rather than migrating, as in the Serengeti. Ngorongoro is also one of the few places in Tanzania where the endangered Rhino can be seen, although they were hiding on the day I was present, because, according to my guide, the winds were too high. Surrounding the Crater is the Ngorongoro Conservation Area, a vast plain that, along with the Serengeti, makes up the territory used by the great herds when they migrate each year in search of water and grazing lands. Occasional circular compounds constructed of acacia branches can be seen in the Conservation Area - these are tribal Maasai villages, as they allowed to live in the Conservation Area (but not in the National Park). Olduvai Gorge, where the Leakeys found fossil evidence of the earliest known hominids, is here, too.