Imagine that you find a layer of rock containing many fossil clams. The layer of rock is 50 km from the ocean. The fossils are a
bout 5 million years old. Clams usually live in shallow ocean water. Based on the fossils, what can you guess about the environment in this area 5 million years ago?
There is no ocean or sea in this area 5 million years ago because the land is present where these fossils live but with the passage of time the geography of that place changes and the ocean covered the area and these fossils remain below the ocean inside the layer of land. So we can conclude from the presence of these fossils that there is no ocean present in these regions 5 million years ago .