Wave-cut platform

Did You Know?

• According to Trenhaile, Sunamura, and Massalink and Hughes, the term 'wave-cut platform' should no longer be used because it assumes wave action is always the cause, which is not true.
• Shore platforms are erosional features that develop when removal of saprock and debris by waves and currents leaves a bedrock surface below the water table.
• Comparable river and lake platforms exist.

Formation

Destructive waves striking a cliff face cause undercutting between high and low water marks through abrasion, corrosion, and hydraulic action, forming a wave-cut notch. This notch enlarges into a cave, and the roof eventually collapses under pressure from freeze-thaw or biological weathering, causing the cliff to retreat landward. The cave floor becomes the wave-cut platform as collapsed material is broken down by attrition, with some debris washed into the sea or deposited as an offshore beach. The constant wave action makes the platform a hostile environment, supporting only certain organisms.

Use of ancient examples

Ancient wave-cut platforms serve as evidence of past sea and lake levels. Raised, abandoned platforms found behind modern beaches indicate higher sea levels in the geological past and help identify areas of isostatic adjustment. Scientific dating or examination of marine fossils on the platform allows determination of when it formed, providing information about historical sea levels. In the United Kingdom and other previously glaciated areas, this has been used to calculate current land uplift rates. Where seismic activity alters coastlines, a series of platforms may record earlier sea levels and earthquake-related uplift.