Depositional Landforms – Landform and their Evolution

Landforms are formed by vast quantities of sand, gravel and debris which are carried by water. Depositional landforms include beaches, spits and bars.

These three form during two different depositional processes. Beaches form as water carrying sediment comes to rest at the coastline; however, spits and bars (which are very similar) form due to sediment transport across the coastline.

The way that these landforms evolve into their final shape depends on whether the waves or currents transporting the sediment change direction or speed after encountering friction with the ground or vegetation along the coastline.

Beaches and Dunes

Beaches are characteristic of shorelines that are dominated by deposition, but may occur as patches along even the rugged shores.

Most of the beaches are made up of sand sized materials. Beaches called shingle beaches contain excessively small pebbles and even cobbles.

Bars, Barriers and Spits

A ridge of sand and shingle formed in the sea in the off-shore zone (from the position of low tide waterline to seaward) lying approximately parallel to the coast is called an off- shore bar.

An off-shore bar which is exposed due to further addition of sand is termed a barrier bar.

The off-shore bars and barriers commonly form across the mouth of a river or at the entrance of a bay. Sometimes such barrier bars get keyed up to one end of the bay when they are called spits.