EROSION BY WATER

Inland waters are an agent of erosion of the first magnitude. In the form of rivers that flow on the surface or underground streams, the water wears away the material through which it passes there and drag the remains into the ocean, leaving deposited in various places, forming new soil and, ultimately, modeling landscape.

Water creates waterfalls, gorges, meanders and deltas. Sometimes certain areas flooded, more or less extensive, the territory. Life has developed more prolific, always on the margins of the rivers.



THE EROSIVE ACTION OF RIVERS


The erosion due to flowing water follows the same stages that naturally divides the course of a river. There is a first stage where mechanical erosion by water and materials that drag is very intense in the upper reaches of river. In the second stage, transport, mechanical erosion is s


This takes place in the middle. Finally, during deposition under predominantly transported materials, the mechanical action is reduced greatly and acts almost exclusively chemical erosion.

The erosion of a river due to water power. It is able to boot chunks of rock, being washed away, act like a hammer on the bed of the river, releasing new pieces. As the channel is not regular, they usually produce eddies that carry sand and gravel, polishing the bottom of the river, creating cavities.

Other times, the slope causes water to form high falls, cascades and waterfalls, some of which reach up to 1000 meters. The drop zone upstream gradually recedes as it wears. In other cases, when the course is great odds, the water "looks" the most frágines, the wear and form gorges or canyons.

In calcareous soils is often the emergence of underground caves erosion caused by water chemistry, which transforms the insoluble carbonate to bicarbonate soluble.

FLOODS

During seasons of heavy rains or melting occurs, the flow of a river can increase that does not fit well within their banks. Then the water overflows the banks. This phenomenon often occurs gradually, but others do it violently, causing a major erosion in the entire territory.

Meandering

The result of the erosion is more or less fine material by the flowing water along the river course. In the middle begin to be deposited when the force of the current is not able to keep these particles in suspension.

But after the erosive force acts on these deposits and wears more for the area where the water velocity is increased, while new materials deposited where it is weakest. The end result is a sinusoidal form deposits called meanders. With time and floods, the river can return to find their way in a straight line, leaving gaps in their margins crescent-shaped.

Deltas
The end of the fluvial erosion process takes place at the mouth of the river, although in some cases the current force is capable of further erosion of the bottom of the continental shelf and form a submarine valley.

In many cases, especially in large rivers with a lot of erosion, the finest materials are deposited at the mouth forming a delta .. The deltas are therefore extensive sedimentary in which there is a constant balance between the destructive force of the flow and deposition of new materials.