Oldupai Gorge, Tanzania

Archaeological site in the eastern Serengeti Plains, Oldupai (or Olduvai) Gorge is a steep-sided ravine about 48 km long and 90 m deep, with subsidiary valleys. Deposits exposed in the sides of the gorge cover a time span from about 2,100,000 to 15,000 years ago. The deposits have yielded the fossil remains of more than 50 hominids, providing the most continuous known record of human presence during the past two million years, as well as the longest known archaeological record of the development of stone-tool industries. Conditions for preservation were unusually favorable at these sites because ashfalls from nearby volcanoes and fluctuations of the lake led to rapid burial of the hominid and associated remains.  Oldupai Gorge was designated part of a UNESCO World Heritage site in 1979. [—Adapted from Encyclopedia Britannica, 2004]

The Gorge	Artist's impression	Upright hominid steps