At Olduvai Gorge in northern Tanzania, natural erosion exposed a series of superimposed geological beds containing rich artifacts and fossil assemblages spanning the past 1.8 million years. The site is famous as a result of excavations conducted there since 1951 under the direction of Mary Leakey and her husband, the late Louis Leakey. This book records the archaeological finds in the upper part of the Olduvai Gorge sequence, covering the period 1.2 to 0.4 million years ago, and includes artifacts and faunal remains excavated from sites in Beds III, IV and the Masek Beds.