In this article, we will discuss The Coastal Plains of India. So, let’s get started.
The Coastal Plains
The Peninsular Plateau of India is flanked by narrow coastal plains of varied width from north to south, known as the West-Coastal Plains and the East-Coastal Plains. These coastal plains differ from each other. They were formed by the depositional action of the rivers and the erosional and depositional actions of the sea waves. According to geologists, the origin of the western and eastern coasts of India may be attributed
to the faulting and subsidence of the Arabian Sea and the Bay of Bengal towards the close of
the Eocene Period. Consequently, alluvial deposits along these coasts are of very recent origin, ranging from Pliocene to recent times. These coastal plains have the evidence of submergence and emergence. The Indian coastal plains may be subdivided into the following three divisions: (i) The Gujarat Coastal Plain, (ii) the west Coastal Plain, and (iii) the East Coastal Plain.
(i) The Gujarat Coastal Plain
The Gujarat plain covers almost the entire state of Gujarat, except the districts of Banaskantha and Sabarkantha. It is formed by the alluvial deposits of Sabarmati, Mahi, Luni, and numerous tiny parallel consequent streams. Part of this plain is the product of depositional activity of the winds and recession of the sea. It contains the Gondwana rocks (Umia Series), resting over the marine Jurassic rocks and capped by Lower Cretaceous (Apatian) beds, The Deccan lava lies over the Umia series.
The eastern section of Gujarat Plain is a projected jet of Sindhu-Ganga alluvial tract in Peninsular India. This projection is the outcome of an extensive Pleistocene sedimentation. Present rivers have further advanced this deposition to the Gulf of Khambat. Among the highlands, mention may be made of the Arasur mountains in eastern Gujarat, the Rajpipla Hills (Satpura)-famous for agate quaries, the Parnera Hills in Bulsar district, Sahyadris in the southern side and igneous complex of the Girnar Hills (Gorakhnath Peak, 1117 m) and Mandav Hills in Kathiwad.
The Rann of Katch is an extensive tract of naked tidal mudflats transected by abandoned and
live creeks. The Gulf of Katch separates the Rann of Katch from the Kathiawar Peninsula. The salt in the soil makes this low-lying marshy area almost barren and unproductive. The whitish vertebrae of salts appear as white bony structures of the dried creeks. Live creeks form dendritic pattern of drainage and there has been accentuation in this pattern due to earthquakes. South of the Rann lies Katch, formerly an island, which is almost surrounded by the Rann except in the south-west.
(ii) The West Coastal Plain
It lies between the Sahyadris and the Arabian Sea. It is about 1400 km long and 10 to 80 km wide. It has an elevation up to 150 m above sea level, reaching more than 300 m at places. The Western Coastal Plain is characterised mainly by sandy beaches, coastal sand-dunes, mud-flats, lagoons, alluvial tracts along rivers, estuary, laterite-platforms and residual hills. The Sahaydris (elevation 750-1225 m) run parallel to the plain and present their steep face to the low lands with Thalghaat and Bhorghat (gaps) in the north and the Palghat (Plakkad Gap) in the south of Nilgiri. The northern part of the west coastal plain, known as the Konkan Plain, is about 530 km long and 30 to 50 km wide. Southward is the Karnataka coastal plain which is about 525 km long and 8 to 25 km wide. It is the narrowest part of the West coastal plain. The southern part is known as the Malabar coast which is about 550 km long and 20-100 km wide. The maximum extension of the Malabar coast is found in the valleys of the Beypore, the Ponnani (draining through Palghat), the Periyar and Pamba Achankovil rivers. This coast is characterised by sand dunes. Along the coast, there are numerous shallow lagoons and backwaters-Kayaks and Teris. These lagoons are linked together to facilitate navigation through small country boats. Here, Vembanad and Asthamudi are the important lagoons of the Malabar coast. It is the homeland to aquatic life like crabs, frogs, mudskippers, birds like terns, kingfisher, cormorants and otters and turtles live alongside the backwaters. The backwaters are important tourist spots, and are of importance for transportation, fishing and even agriculture. The region has deposits of Monazite sands which is reddish brown and rich in phosphate. Monazite is radioactive due to the presence of thorium.
(iii) The Eastern Coastal Plain
The eastern coastal plain lies between the Eastern Ghats and the Bay of Bengal, and stretches along the coasts of Odisha, Andhra Pradesh, and Tamil Nadu. These plains are formed by the alluvial fillings of the littoral zone comprising some of the largest deltas of the world. The East-Coastal Plains consist mainly of Recent and Tertiary alluvial deposits. These are gentle, monotonous plains rising gently westward to the foot of the Eastern Ghats. The monotony of the topography is broken by the presence of numerous hills. This coastal plain has a straight shoreline with well defined beaches of sand and shingles. The most famous is the Marina Beach in Chennai. All along the coast, there are several sandbars generally in front of the river mouths. There are some of the important lagoons of India along the Eastern coast, of which, Chilka in the south-west of the Mahanadi delta is the biggest lake (65 kmx8 km) in the country. The Kulleru lake lies between the deltas of Godavari and Krishna, while the Pulicat lake lies further south on the border of Andhra Pradesh and Tamil Nadu.