Olduvai Gorge

The gorge is a steep-sided ravine roughly 48 km long and up to about 100 m deep, carved by a seasonal river through layers of volcanic ash and lake sediment laid down over roughly the last two million years. Because each layer can be dated and each is packed with fossils and stone tools, the walls of the gorge read almost like a book — which is why it became one of the most intensively studied archaeological landscapes on earth.

Mary and Louis Leakey worked here for decades. In 1959 Mary Leakey found the skull now classified as Paranthropus boisei, and in the early 1960s the team described Homo habilis from remains found in the gorge. Stone tools from the lowest beds gave their name to the Oldowan industry, the earliest widely recognised stone-tool tradition. Later work by many teams, Tanzanian and international, has kept adding to the picture.

About 45 km to the south lies Laetoli, where in the 1970s Mary Leakey’s team uncovered a trail of hominin footprints preserved in hardened volcanic ash, dated to approximately 3.6 million years ago and generally attributed to Australopithecus afarensis. They are the oldest clear evidence that our ancestors walked upright. The original trackway is protected and not open to visitors, but casts and the story are presented at the Olduvai museum, which sits on the rim with a view down the gorge and is an easy stop on the road between Ngorongoro and the Serengeti.