Topic: Erosion LandformsAim: The Formation of Caves, Arches, Stacks and Stumps

CAVES, ARCHES, STACKS AND STUMPSBY: KWAKU BONSU

CavesAlthough coastal headlands consist mostly of resistant rock, there are always weak points such as faults and joints. These faults are forced to become larger and larger by the three erosion processes: corrasion, solution and hydraulic pressure. These faults and joints then eventually become small caves. This can be observed in the picture to the right of the Old Harry Rocks of Dorset in Southwest England.

ArchesThe caves are being widened and enlarged by the sea (through the erosion processes: corrasion, solution and hydraulic action). The waves eventually cut through the caves and form natural arches. The foot (lower end) of the arch is constantly being eroded and the roof of the arch soon becomes too heavy and it collapses.

StacksOnce the roof of the arch has fallen down, it leaves an isolated column the rocky cliff to stand alone called a stack. This stack continues to be eroded at the lower part. The undercut parts of the stack are called wave-cut notches. Sooner or later the stacks base will become too thin to support the column of rock and the stack will collapse.

StumpsOnce the stack has been collapsed due to lack of support, it leaves an even smaller portion of the cliff called a stump. This is the lower portion of the stack that was not broken down. The stump continues to be eroded and it slowly breaks down.

Geography Project - Coastal Erosion - YouTube.flv

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