V shaped valleys

River valley with a V-shaped cross-section. Such valleys are usually found near the source of a river, where the steeper gradient means that there is a great deal of corrasion (grinding away by rock particles) along the stream bed, and erosion cuts downwards more than it does sideways. However, a V-shaped valley may also be formed in the lower course of a river when its powers of downward erosion become renewed by a fall in sea level, a rise in land level, or the capture of another river (see rejuvenation).
The angle of the V-shaped cross-section depends on the rate of uplift of rock, the type of rock, the erosive ability of the river, the type of climate, and the stage of the river.