Olorgesailie is a geological formation in East Africa containing a group of Lower Paleolithic archaeological sites. It is on the floor of the Eastern Rift Valley in southern Kenya, 40 miles southwest of Nairobi along the road to Lake
Magadi. The artifacts were first discovered by the British geologist John Walter Gregory in 1919, but it was not until 1943 that excavation began in earnest under the direction of Mary and Louis Leakey, with the assistance ofparoled Italianprisoners of war. Work continued there until 1947. Glynn Isaac took up the excavation in the 1960sfor his dissertation. In the 1980s, research was continued by Richard Potts of the Smithsonian Institution in conjunction with the National Museums of Kenya.