Olduvai Gorge
During a period of major faulting and volcanism roughly 600,000 to 400,000 years ago, the Masek Beds were made. These beds contained tools from an industry made by modern humans, followed by the Ndutu Beds (400,000 to 32,000 years ago), and the Naisiusiu Beds (22,000 to 15,000 years ago).