Olduvai Gorge is a 30 mile, 295 foot deep ravine located in the eastern Serengeti Plains of northern Tanzania, within the Ngorongoro Conservation Area. According to geologists, the region's gradual accumulation of lake sediments punctuated by sudden deposits of layers of volcanic ash and lava over several million years provided excellent conditions for preserving fossilized remains of plants and animals. Subsequent faulting due to seismic forces during the Pleistocene era followed by slow and steady erosion from wind and water runoff have cut a slice through these rock strata, granting scientists access to a treasure trove of precious geological and archeological clues to the region's ancient history. This simulated natural-color image of Olduvai Gorge was acquired on February 1, 2001, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra satellite.