Mount Longonot, 9,110 feet high, lies on the floor of the Great Rift Valley, thirty-five miles northwest of Nairobi. Aptly called by the Maasai Ol doinyo Longonot, the mountain of many valleys and gullies, it is of volcanic origin. The last eruption of a parasitic cone happened only 5,000 years ago. Steam still issues from its crater wall, indicating that Longonot is now in a dormant phase rather than extinct.