Why are the oldest parts of the ocean floor less than 200 million years old?

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.

Where is the vascular system located

Can someone answer all these questions i need it done by tonight. once again