Wave tank experiments on erosion of rocky coasts

Abstract

Erodable blocks representing vertical cliffs and shore platforms were exposed to attack by artificially generated waves. Maximum erosion in all blocks occurred above still water level. Vertical cliffs became deeply notched in a form which contained no horizontal portion and which had the lower segment located below still water level. Platform shapes were degraded by cutting on the platform surface and rounding of the leading edge. No wave-tank evidence was found to support the contention that high tide shore platforms are presently being formed by storm wave activity. Notches on the sides of the blocks were caused by aeceleration of waves constricted between the block and tank sides. Such constrictton and attendant increase in velocity may also favour rapid erosion in sea arches, caves and closely spaced stacks. Erosion debris moved rapidly from the base of the model cliff and was not involved in subsequent block notching.