Ripples that rise on the surface of the sea due to the movement of air are known as waves. In coastal regions, waves form many types of erosional and depositional topographies by the process of hydrolysis, corrasion, attrition and hydraulic pressure and by deposition of debris.
Following is their description:
1. Erosional Topographies:
(a) Cliff: Erosion which takes place due to the continuous impact of the waves on the base forms a steep slope which is known as cliff.
(b) Cave: Egg – shaped structure formed by the erosion of tender rocks in regions of hard and soft rocks situated parallel to the shore is known as cave.
(c) Sea cave: Due to continuous erosion of gorges formed by waves in coastal regions, sea caves are formed.
(d) Blow outs: Sea waves form holes on the ceiling of the coastal caves which are known as blow outs.
(e) Natural arch: Mutual conjunction of caves formed from two sides on the coast result into the formation of natural arch.
(f) Stack/Cave pillar: Pillar which is formed due to the breaking down of the ceiling of a natural arch is known as cave pillar or stack.
(g) Wave cat platform: This is platform built due to the cliff continuously shifting backwards.
2. Depositional Topographies:
(a) Beach: Beaches are formed due to deposit of debris by the waves on the edges of the seashore.
(b) Cusp Beach: Triangular beach formed from pebbles, stones, boulders, etc. which extends vertically towards the sea is known as cusp beach.
(c) Spit: Deposit made by waves in the form of tongue towards the sea is known as spit.
(d) Bars: Ridges or dams formed from deposition performed by waves are known as bars.
(e) Offshore bars: Dam or wall built parallel to the coast but far away from it is known as offshore bar.
(f) Hook: Crescent circuitous deposit of spit is known as hook.
(g) Loop: When the hook turns towards the hoop, a loop-shaped structure is formed.
(h) Connecting Bars: Dam, ridge or wall which joins two islands are known as connectors or connecting bars.
(i) Tumbolo: Bars which connect the islands with the shore are known as tumbolos.
