What was the main reason ancient civilizations were established along the Nile River?

What is the approximate circumference of the circle shown below? 12.2 cm

Sandstones that form in aeolian (wind/desert) environments appear very different from other sandstones, such as those formed in a beach/ shoreline environment and in rivers on land. give three identifying properties for each of the three sandstones that would tell a geologist which depositional environment they formed in. consider things such as the relationship between transportation and grain size, shape, roundness, sorting, fossils and composition.

How much water is in the ocean in cubic kilometers