The Great Indian Desert is a rolling sandy plain covered by sand dunes and most of these are crescent-shaped sand dunes, called Barchans of longitudinal dunes. Seif dunes are thought to develop from barchans if the direction of the wind changes. The rainfall in this region is quite low-below 150 millimetres per year.
During the rainy season, some streams but as these do not have enough water to reach the sea they disappear slowly into the sand again. The only exception is the river Luni, which is a large river. Beyond the Western Ghats and the Eastern Ghats, the plateau is bordered by narrow coastal strips. The western strip runs along the Arabian Sea, while the eastern strip is along the Bay of Bengal.
The western coastal area is divided into three sections:
- The Kannad Plain and
- The Malabar Coast.
The eastern coast runs along the Bay of Bengal, displays wide and level stretches and has different local names. In the northern parts, people refer to this coastal area as the Northern Circars while people in the south call it the Coromandel Coast.
Large rivers like the Mahanadi, the Godavari, the Krishna and the Kaveri form a wide delta on the eastern coast. The lake Cilika on the eastern coast is said to be the largest salt water lake in India. It is located in Orissa, to the south of the Mahanadi delta.
Off the mainland, the country consists of two groups of islands or archipelagos:
- The Lakshadweep Islands group, and
- The Andaman and Nicobar Islands.
The Lakshadweep Islands overall consists of small coral islands. Coral polyps are microscopic marine organisms, which have short life spans. Coral reefs are built of a combination of a hard rock-like secretion from the coral polyps and their skeletons.
There are three main kinds of reefs:
- Barrier reef,
- Fringing reef and
A barrier reef is one that is separated from a mainland or island shore by a deep lagoon like The Great Barrier Reef of Australia. An atoll is a circular barrier reef. There is no central island, and the reef extends all the way around the lagoon, forming the shape of a horseshoe. A fringe reef is one that is directly attached to a shore.
Before 1973, the Lakshadweep Islands were known as Laccadive, Minicoy and Amindive. The Andaman and Nicobar Islands is a long chain of islands extending from north to south, located in the Bay of Bengal. The entire group of islands is divided into two broad categories: the northern islands are called the Andaman, and the southern islands constitute the Nicobar. The Andaman and Nicobar Islands house India’s only active volcano located on the Barren Island.