3.1.2.2 Systems and Processes- Marine processes of Erosion

Processes of Marine Erosion

• hydraulic action/ power
• abrasion/ corrasion
• attrition
• corrosion

These processes are most active  around the whigh water mark when high energy waves, associated with storm conditions, strike coasts made of incoherant rocks.

1. Hydraulic Action

This is the main erosive force. The breaking wave traps air as it hits a cliff face. The force of the water compresses this air into any gap in the rock face, creating enornous pressure within bedding plates and joints.

As the water pulls back, there is an explosive effect of the air under pressure being released. As the air expands quickly, the resulting pressure sends shock waves thrugh the cliff. The overall effect of this overtime is to weaken the cliff face - storms may then remove large chunks of rock (wave quarrying).

The sheer force and weight of water itself (without debris) can exert an enormous pressure (of up to 30 tones per square metre) upon a rock surface causing it to weaken. Such activity is known as wave pounding. Bubbles of air can be forced into fissures to loosen rocks- this is known as cavitation. The effect of hydraulic action can reachfar beyond the water line and so can create geos and blowholes. 

2. Abrasion (corrasion)

The material the sea has picked up also wears away rock faces. Sand grains, shingle (pebbles) and boulders are…