Here is your paragraph on the coastline of India!
India has about 6100 km long coast most of which is more or less uniform and regular with a few creeks, inlets, back waters and promontories here and there.
Success has opined that the straight and regular coastline of India is the result of disruption and faulting of the Gondwanaland during the Cretaceous period. As such the coast of India does not offer many sites for good natural harbours.
The peninsular shape of South India has divided the entire coast into western and eastern parts with Kanniyakumari at the southernmost tip as the dividing point. The Bay of Bengal and the Arabian Sea came into being during the Cretaceous or early Tertiary period after the disintegration of Gondwanaland.
The east coast of India extends from the Ganga delta to Kanniyakumari facing the Bay of Bengal. It is marked by deltas of great rivers like the Mahanadi, the Godavari, the Krishna and the Cauvery. There are several lagoons of which the Chilika Lake and the Pulicut lagoon are outstanding.
The West Coast runs almost straight in the north-south direction right from the Gujarat plains to Kanniyakumari. However, it is dotted with a large number of coves, creeks and a few estuaries. The estuaries, of the Narmada and the Tapi are well known. The Malabar Coast in the south has some lakes, lagoons and backwaters, the largest being the Vembanad Lake.
There are evidences to show that large parts of Indian coast have undergone submergence and emergence during the geological times and even during the historical times. The most outstanding example of submergence of the sea coast is the existence of a submerged forest on the eastern side of the island of Mumbai.
It is located at depths of 6-12 m below the present sea level where a number of tree-stumps are seen with their roots in situ embedded in the old soil. The submergence is further proved by the raised terraces formed of coral reefs or loosely cemented fragmentary shell limestone rocks. A similar submerged forest or old land surface, about half an acre, is seen on the Tinnevelli coast.
A thick bed of lignite found at Pondicherry 73 m below ground level also provides proof of submergence. Such vegetable debris is also found in the Ganga delta. Sudden increase in the depth of sea about 30 km from the coast of Makran is due to the submergence of a cliff lying at the coast. Marine archaeologists have recently discovered the ancient city of Dwarka lying under shallow waters off the coast of Saurashtra.
Examples of both submergence and emergence have been found in the Rann of Kuchchh. As a result of the great earthquake in 1819, an area of 5180 sq km on the western border of the Rann of Kuchchh was suddenly submerged under the sea upto a depth of 3.6 to 4.5 m.
The fort of Sindree on the sea coast was completely submerged excepting a single turret which remained above the water level. Simultaneously another area of about 1550 sq km was elevated by several metres.
In fact there have been repeated falls in sea levels in the Rann of Kuchchh area which is evident from the presence of coastal dunes, sea cliffs in the islands of the Gulf, sea caves within the plains and raised beaches of littoral concrete on the fringes of the islands.
The total fall in the sea level has been estimated at 26 m. Even during historic times the Rann of Kuchchh was a gulf which was silted up by the rivers falling into it. This process was supplemented by the slow elevation of the floor of the gulf and the entire area was converted into a low-lying tract.
Before the Rann became dry, the Luni River used to enter the Arabian Sea through the Kori estuary crossing the entire length of the great Rann, and the Western Вanas flowed over the Little Rann into the Gulf of Kuchchh. Some islands off the Arabian Sea coast came into existence due to submergence of low-lying areas around them. The coral archipelago of the Lakshadweep islands probably marks the site of submerged land.
Several evidences of uplift of the western coast have been given by the geologists. Raised beaches are found at altitudes ranging between 30-45 metres at many places, while marine shells are found at many places on land at a height far above the level of tides. The steep face of the Sahyadri parallel to the west coast of India, suggests that the escarpment is the result of a recent elevation of the Ghats from the sea.
Proofs of uplift of the coastal plain of Kerala are numerous and decisive. The occurrence of coral reefs below the alluvium several kilometres from the present coast and the presence of a number of lakes, lagoons, backwaters and spits are a few of them. At least two phases of uplift have been noticed.
Away from the coast in the Bay of Bengal the Andaman and Nicobar Islands were once connected with the Arakan Yoma. They have come into being as a result of submergence of the surrounding low- flying areas in the geological times.
However, the shape and size of some of the islands near the Ganga delta change with the change in sea level. Old islands disappear and some new islands emerge above the sea level. The recent emergence of New Moore Island in the Ganga delta is an outstanding example of such changes.
Sri Lanka was a part of India in the geological times, and the two landmasses were connected with each other by Adam’s Bridge. This link was drowned in the Quartemary times and is now represented by Pamban Island on Indian side and the Mannar Island on the Sri Lankan side along with several other small islands lying between these two islands.