The oldest fossils are typically found in rock layers called sedimentary rocks, specifically in areas known as sedimentary basins. These basins are often located on the Earth's surface or beneath the ocean, where layers of sediments, such as sand, mud, or silt, gradually accumulate over millions of years. Over time, these sediments compress and harden, forming sedimentary rocks that preserve the fossils. The older the sedimentary rock layer, the older the fossils it contains. Therefore, the oldest fossils are found in the deepest layers of sedimentary rocks.
