Class 6

The end of a river is its mouth, or delta. At a river’s delta, the land flattens out and the water loses speed, spreading into a fan shape. Usually this happens when the river meets an ocean, lake, or wetland.

From its source, a river flows downhill as a small stream. Precipitation and groundwater add to the river’s flow. It is also fed by other streams, called tributaries. For instance, the Amazon River receives water from more than 1,000 tributaries.

How do rivers start?The place where a river begins is called its source. River sources are also called headwaters. Rivers often get their water from many tributaries, or smaller streams, that join together. The tributary that started the farthest distance from the river’s end would be considered the source, or headwaters.

Deposition is the laying down of sediment carried by wind, flowing water, the sea or ice. Sediment can be transported as pebbles, sand and mud, or as salts dissolved in water. Salts may later be deposited by organic activity (e.g. as sea shells) or by evaporation.

Mass wasting is the movement of rock and soil down slope under the influence of gravity. Rock falls, slumps, and debris flows are all examples of mass wasting. Often lubricated by rainfall or agitated by seismic activity, these events may occur very rapidly and move as a flow.

What is the relationship between earthquakes and landslides? If a slope that has not previously experienced mass wasting is covered by surface materials that are saturated with water, the vibrations of an earthquake may trigger liquefaction of these materials, causing them to travel downslope.

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of “mass wasting,” which denotes any down-slope movement of soil and rock under the direct influence of gravity.

River transport processes remove material, creating mountain valleys. They carry sediment and nutrients downstream, which sustains lowland landscapes and even marine ecosystems.

Three River Channel Processes are– 1) Erosion ((The wearing away of the land)2) Transportation (The movement of eroded material)3) Deposition (The laying down of eroded material)

The action of running water which include streams, rivers, and rainfall, have constantly shape the surface of the surface of earth through erosion and depositional processes. River (or running water) is one of the most active agent of land form development.