RiversAbout 70% of Earth surface is covered with water and is found in rivers, lakes, streams and oceans. A river is a flowing, moving stream of water. Usually a river feeds water into an ocean, lake, pond, or even another river. Rivers can vary in size and there is no hard definition or rule on how big a flow of water must be to be categorized as a river. Water from a river can come from rain, melting snow, lakes, ponds, or even glaciers. Rivers flow downhill from their source. They are cons...