Rivers

Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground in deserts and seas.

A river's contribution to the water cycle is that it collects water from the ground and returns it to the ocean. Rivers may come from mountain springs, melting glaciers or lakes.

A delta is where a river meets the sea. A special environment is created when the fresh water from the river mixes with the salty ocean water. This is environment is called estuary.

The longest river is the Nile River in Africa, and the Amazon River in South America carries the most water. The muddiest river is the Yellow River in China.