Presented by Asst.Professor R.K.Pawar Dept.of Geography WELCOME Topic Presented by Asst.Professor R.K.Pawar Dept.of Geography SSVPS Arts,Commerce & Science College Shindkheda

The sea waves carry on the work of denudation along the coasts The sea waves carry on the work of denudation along the coasts. The power wave to erode depends on the rocks fragments which they carry. It also depends on the velocity of the winds, as waves derive their energy from them. Definition : Sea Wave may be defined as ‘jig-jag horizontle flow of ocean water in certain direction with a specific height and length’ it is simply known as Sea Wave. Wave Length Wave Height

Mechanism of Marine Erosion: The following Processes are involved in marine erosion: Hydraulic Acton: A Strong wind raises huge waves which dash against the cliffs on sea shore with high speed. The cliff-faces have cracks and joints that contain air. When the wave dashes the cliff-faces, the air in the cracks and fissures gets compressed. When sea- waves retreat, the pressure is released. Suddenly the air in the cracks and fissures expands with an explosive effect. Corrosive Action: Course sands, pebbles, cobbles and boulders are the major tool’s of erosion Coastal rocks. They corral the coastal rocks and cliffs. But during powerful Storm, the waves carry larger fragments and boilers which have a capacity to erode the cliff fatly and prominently. Attrition: The rock fragments are pounded on the cliffs and against each other as these particles are carried to the coast (swash) and them it flows back along the beach slope (backwash). This way the fragments themselves worn down. This action by which they worn down known as Attrition. Solvent Action: The dissolved chemical in sea water is responsible for weakening of the rocks like limestone and Chalk by solvent action of sea water.

Erosional Features Produced by Sea-Wave Sea cliff is a very prominent feature of marine erosion. When the coast facing the sea has a wall- like steep slope; it is known as sea-cliff. A highland is lying close the coast. The waves are attacking against the hill. Due to the action of the sea-waves, a notch is formed at the point of wave attack between the high and low tide levels. Erosional Features Produced by Sea-Wave 1] Sea Cliff and Wave cut platform:

1] Sea Cliff and Wave cut platform:

1] Sea Cliff and Wave cut platform:

2) Sea- caves and Arch : Sea- caves may develop along a ling of weakness at the base of a cliff which has been subjected to prolonged wave action, Sea caves are formed along the coast where the weak and strongly jointed rocks are there. The joints are widened into large cavities and hollows which are further enlarged due to gradual wave erosion into sea-caves. The sea-caves are more frequently; formed in carbonate rocks mainly limestone’s and Chalks because they are erode more by solution processes.

Sea- caves

2) Sea- caves

2) Sea- caves Sea- caves

2) Sea- caves and Arch :

3) Sea Arch: When caves are formed on opposite sides of seaward projecting headland, a natural arch is formed due to-coalescence of two caves known as sea arch. 4) Sea Stacks: The roof of the sea arch becomes very thin because of erosion by sea-waves. It collapses, and an isolated pinnacle called a sea stack is left in front of the cliff.

4) Sea Stacks:

4) Sea Stacks with Arch:

Landforms produced by Sea-Waves

Depositional features produced by Sea-Waves The depositional work carried out by the Sea-Waves is normally a slow and steady process. The eroded materials transported along the shore are deposited in the areas of low wave energy and creates a variety of landforms. Following are some of the depositional features produced by Sea-Wave.

1) Beaches: A beach is a land on shore between the high water mark and the low water mark. Beaches can be composed of Sand, Cobbles, pebbles, boulder, fine silt and clay. In width, beaches vary from a few meters to several kilometers. Beaches are generally formed when sea is calm and winds are low velocity. Beaches are generally classified on the basis of the beach materials. The classification is given below. A) Sand beach:- Sand brains ranging in size between 0.5 to 2 mm. B) Shingle beach:- A shingle beach is composed of Flat, circular, smooth stones and pebbles ranging in size from 2 to 100 mm. C) Boulder beach:- It consists of pebbles in size more than 100 mm.

a) Sand Beach:

b) Shingle Beach:-

C) Boulder Sea Beach:-

2) Off- Shore bars:- Off-Shore bars are elongated deposits of sand, Shingle or mud occurring in the sea, more or less parallel to the shoreline but are not attached to the land. 3) Spites:- If the sand bars are formed in such a way that their one end is attached to the land while the other end opens out towards the open sea they are called Spits. A few spits have been observed on the eastern and western coast of India.

4) Lagoons and Spites :- The shallow water cut off by an offshore bar connected only by a tidal inlet to the open sea is converted in to lagoons. The sea water enclosed between the coast and sandbar becomes partially enclosed lake known as lagoon. Gradually lagoons may be filled with sediments. Lake Chilka, Pulicat and Vembanad in India are example of lagoons.

4) Lagoons and Spites :-

5) Mudflats and Salt Marshes:- Mudflats and Salt Marshes are developed behind the spits and bars. Fine silt particles carried along with high tides and alluvial carried by the river deposited silted area. Windblown sand also traps by vegetation that grows in this area. This raises the surface of marshes. Many marshy aras and mudflats are developed. Such structures are observed at the coast of Britain, Netherlands, Germany and Denmark.

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Salt farms on the Sea Coast