V-shaped valley

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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.

The crown emblem was modernized in 1982. The colours date back to the 18th century. Effective date: 18 September 1982. >>