If water in any place falls from height more than one meter, this site is already considered falls. In the world there is a set of natural falls, they are born for various reasons and sooner or later die.
Instruction
1. Most often falls are formed when in line with the river of more firm breed is replaced by soft. Water constantly washes away a river bed and if one breed is softer other, this process will unevenly occur. Gradually strong breed forms a ledge which becomes higher and higher, water begins to wash away stronger water behind it as is valid not only currents, but also falling force from height.
2. The breed of which the ledge is formed is stronger, the falls will longer exist if it is washed away, though more slowly, than the site behind it, then shortly the falls will disappear as the surface of the course will even out. Also falls gradually move upstream the rivers as the breed of a ledge what firm it would not be is all the same washed away.
3. Falls can arise not only owing to natural degradation of the course for a long time. Sometimes there is some natural disaster - a mountain collapse, a volcanic eruption, an earthquake, and the watercourse is blocked. Gradually the level of the river reaches height of an obstacle and water begins to fall from height to the course where it proceeded earlier. Such falls appear very quickly.
4. The whole cascades of small falls are often formed, it occurs thanks to suitable structure of breeds in this place of the course. Sometimes the crest of falls does not maintain constant load of water only in one place, the high break remains, but water punches to itself in it the thin course and does not fall steeply down any more, and rolls down an inclined trench.
5. Some falls arise where the plateau sharply passes into the lowland, on Earth there are a lot of places with such relief. The deep rivers of plateaus steeply fall from huge height down.
6. Glaciers became the reason of emergence of some falls. At the time large glaciers formed long narrow valleys, and small glaciers crashing into them sideways created apertures in steep rocks of the main valley. Now from these apertures the mountain rivers flow. It is a lot of such falls of glacial origin in the Alps.