Olduvai Gorge

2°58S 35°22E. A gorge within the Ngorongoro conservation area of the Rift Valley, N Tanzania. It is an important hominid site, with deposits extending from just under 2 million years ago down to recent. It was excavated by Louis and Mary Leakey, who recovered much archaeological and faunal material as well as important fossils of Australopithecus boisei, Homo habilis, and Homo erectus. Besides these finds, the Gorge has provided valuable evidence of the ecology and behaviour of early hominids.

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.

The stratigraphy is extremely deep and layers of volcanic ashes and stones allow radiometric dating of the embedded artifacts, mostly through potassium-argon dating. The first artifacts in Olduvai (pebble tools and choppers) date to circa 2 million years ago but fossil remains of human ancestors have been found from as long as 2.5 million years ago.

The earliest archaeological deposit, known as Bed I, has produced evidence of campsites and living floors along with stone tools made of flakes from local basalt and quartz. It is now thought that the Oldowan toolmaking tradition started about 2.6 million years ago.

The Olduvai Gorge bears the distinction of having the oldest known evidence of mammoth consumption, attributed to Homo erectus around 1.8 million years ago.

Above this, in Bed II, pebble tools begin to be replaced by more sophisticated handaxes of the Acheulean industry and made by Homo erectus. This layer dates to around 1.5 million years ago.

Beds III and IV have produced Acheulean tools and fossil bones with Neandertal characteristics which were used until around 600,000 years ago.

Beds above these contained tools from a Kenya-Capsian industry made by modern humans and are termed the Masek Beds (600,000 to 400,000 years ago), the Ndutu Beds (400,000 to 32,000 years ago), and the Naisiusiu Beds (22,000 to 15,000 years ago).

Also located on the rim of the Gorge is the Olduvai Gorge Museum.

Olduvai is also the theme of the Olduvai theory, which states that industrial civilization will have a lifetime of less than or equal to 100 years.