Explain the processes that occur to form an arch along a coastal landscape.

In order for an arch to form erosional processes must take place to firstly form a crack within the cliff face. In most cases for this crack to form, hydraulic action takes place. This involves water entering a tiny crack within the cliff face. The water then expands which forces the rock off the cliff and into the sea. This produces a larger hole. Other erosional processes now take place (abrasion, corrasion and attrition) which cause the hole to widen and erode back. Eventually, over thousands of years, the hole becomes a cave and erodes through to the back of the cliff face and an arch is formed.