Simplify the following text for a Grade 7 native English-speaking person.
Original: At Koobi Fora , there are archaeological sites with evidence of control of fire by Homo erectus 1.5 million years ago , with the reddening of sediment that can only come from heating at 200 â '' 400 Â C. There is a hearth-like depression at a site in Olorgesailie , Kenya .
Simplified: At Koobi Fora , sites FxJjzoE and FxJj50 show evidence of control of fire by Homo erectus at 1.5 Mya , with the reddening of sediment that can only come from heating at 200 â `` 400 Â C. A `` hearth-like depression '' exists at a site in Olorgesailie , Kenya .