How are Beaches Shaped By Deposition?

Wave TypesConstructive Waves• They have a strong swash and a weak backwash.• This allows a neat increase of material• These waves are flatter and smaller than destructive waves• Material spills forward building up on the beach.

Wave TypesDestructive Waves• Destructive waves are steep and high.• These waves have much more energy than constructive waves• Most of this is used by the backwash to transport material back down

the beach.• Therefore the load is deposited below the low water mark.• Destructive waves are more common where the fetch is low.

Long Shore Bars• At the lower edge of beaches sand accumulates to form longshore

bands.• These are parallel to the waves• This material has probably been combed from the beach by

destructive waves

Runnels and RipplesRunnels• Runnels separate pools of standing water

• This happens at low tide

Ripples• As the slope of the beach increases small ripple marks appear• This is made as the tide moves over the beach.

Beach Cusps• Material at the top of the beach is of a large calibre and this supports

steeper concave slopes.

• Beach cusps occur when this material is absorbing the wave swash

Berms and Storm BeachesBerms• Large waves reaching the high tide limit build up ridges or berms

Storm Beaches• These consist of larger pebbles and even boulders.• This forms only under high energy conditions of a surge or spring

tide.

By Deborah Durkin and

Amy Smiles