Why does the map of the mississippi river watershed contain both the river system and the land that surrounds it?

All of the smaller rivers or tributaries (Ohio River into Mississippi)  All of the ... water that flows over land and has not been absorbed into the ground.

the precambrian aged rocks could be found in australia. australia is a region that has a lot of ancient civilization history from million years ago. in this region, there are a lot of recognizable fossils buried in its land which is considered a precambrian-aged rocks

landlessness of ordinary people

^^something like that^^^