- Amount of water on Earth is constant, and it is always circulating through this hydrologic cycle.

- Running water does 3 things:

1) Erosion
- overland flow by mass wasting brings in material to rivers and streams
- water also acts like a hot knife in butter, and cuts down through the soil and rocks in flows on. Material it cuts through is worn away by the running water
- coarse sediment in the water acts like the sharp edge to the knife.

2) Transportation

- competence of a stream: a measure of the maximum size of particles a stream can transport, from large to small.
- capacity: maximum amount of material (sediment) a stream can carry
- streams and rivers transport weathered particles of rock and soil away from a source area, to be deposited at a later time in a different place.

3) Deposition

- whenever water velocity decreases, some sediment will be deposited.
- sorting: particles of similar size deposited at the same time, depends on the critical settling velocity of a certain particle size
- well sorted material is called alluvium.

- Oceans represent 71% of the Earth's surface