The Western Ghats

The Western Ghats, also called the Sahyadri, are a north-south chain of mountains or hills that mark the western edge of the Deccan plateau region. They rise abruptly from the coastal plain of the Arabian Sea as an escarpment of variable height, but their eastern slopes are much more gentle. The Western Ghats contain a series of residual plateaus and peaks separated by saddles and passes. The hill station (resort) of Mahabaleshwar, located on a laterite plateau, is one of the highest elevations in the northern half, rising to 4,700 feet (1,430 meters). The chain attains greater heights in the south, where the mountains terminate in several uplifted blocks bordered by steep slopes on all sides. Those include the Nilgiri Hills, with their highest peak, Doda Betta (8,652 feet [2,637 metres]); and the Anaimalai, Palni, and Cardamom hills, all three of which radiate from the highest peak in the Western Ghats, Anai Peak (Anai Mudi, 8,842 feet [2,695 meters]). The Western Ghats receive heavy rainfall, and several major rivers—most notably the Krishna (Kistna) and the two holy rivers, the Godavari and the Kaveri (Cauvery)—have their headwaters there.

The Eastern Ghats

The Eastern Ghats are a series of discontinuous low ranges running generally northeast-southwest parallel to the coast of the Bay of Bengal. The largest single sector—the remnant of an ancient mountain range that eroded and subsequently rejuvenated—is found in the Dandakaranya region between the Mahanadi and Godavari rivers. That narrow range has a central ridge, the highest peak of which is Arma Konda (5,512 feet [1,680 meters]) in northeastern Andhra Pradesh state. The hills become subdued farther southwest, where they are traversed by the Godavari River through a gorge 40 miles (65 km) long. Still farther southwest, beyond the Krishna River, the Eastern Ghats appear as a series of low ranges and hills, including the Erramala, Nallamala, Velikonda, and Palkonda. Southwest of the city of Chennai (Madras), the Eastern Ghats continue as the Javadi and Shevaroy hills, beyond which they merge with the Western Ghats.

Inland regions

The northernmost portion of the Deccan may be termed the peninsular foreland. That large ill-defined area lies between the peninsula proper to the south (roughly demarcated by the Vindhya Range) and the Indo-Gangetic Plain and the Great Indian Desert (beyond the Aravalli Range) to the north.

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The Aravalli (or Aravali) Range runs southwest-northeast for more than 450 miles (725 km) from a highland node near Ahmadabad, Gujarat, northeast to Delhi. Those mountains are composed of ancient rocks and are divided into several parts, in one of which lies Sambhar Salt Lake. Their highest summit is Guru Peak (5,650 feet [1,722 meters]), on Mount Abu. The Aravallis form a divide between the west-flowing streams, draining into the desert or the Rann of Kachchh (Kutch), and the Chambal and its tributaries within the Ganges River catchment area.

Between the Aravallis and the Vindhya Range lies the fertile, basaltic Malwa Plateau. The plateau gradually rises southward toward the hills of the Vindhya Range, which is actually a south-facing escarpment deeply eroded by short streams flowing into the valley of the Narmada River below. The escarpment appears from the south as an imposing range of mountains. The Narmada valley forms the western and principal portion of the Narmada-Son trough, a continuous depression running southwest-northeast, mostly at the base of the Vindhya Range, for about 750 miles (1,200 km).

To the east of the peninsular foreland lies the mineral-rich Chota Nagpur plateau region (mostly within Jharkhand, northwestern Odisha [Orissa], and Chhattisgarh states). It is a region of numerous scarps separating areas of rolling terrain. To the southwest of the Chota Nagpur plateau is the Chhattisgarh Plain, centered in Chhattisgarh on the upper course of the Mahanadi River.

Most of the inland area south of the peninsular foreland and the Chota Nagpur plateau is characterized by rolling terrain and generally low relief, within which a number of hill ranges, some of them mesalike formations, run in various directions. Occupying much of the northwestern portion of the peninsula (most of Maharashtra and some bordering areas of Madhya Pradesh, Telangana, and Karnataka) is the Deccan lava plateau. The mesa-like features are especially characteristic of that large fertile area, which is cut across by the Satpura, Ajanta, and Balaghat ranges.

Coastal areas

Most of the coast of India flanks the Eastern and Western Ghats. In the northwest, however, much of coastal Gujarat lies to the northwest of the Western Ghats, extending around the Gulf of Khambhat (Cambay) and into the salt marshes of the Kathiawar and Kachchh (Kutch) peninsulas. Those tidal marshes include the Great Rann of Kachchh along the border with Pakistan and the Little Rann of Kachchh between the two peninsulas. Because the level of the marshes rises markedly during the rainy season, the Kachchh Peninsula normally becomes an island for several months each year.

The area farther south, especially the stretch from Daman to Goa (known as the Konkan coast), is indented with rias (flooded valleys) extending inland into narrow riverine plains. Those plains are dominated by low-level lateritic plateaus and are marked by alternating headlands and bays, the latter often sheltering crescent-shaped beaches. From Goa south to Cape Comorin (the southernmost tip of India) is the Malabar coastal plain, which was formed by the deposition of sediment along the shoreline. The plain, varying between 15 and 60 miles (25 to 100 km) wide, is characterized by lagoons and brackish, navigable backwater channels.

The predominantly deltaic eastern coastal plain is an area of deep sedimentation. Over most of its length it is considerably wider than the plain on the western coast. The major deltas, from south to north, are of the Kaveri, the Krishna-Godavari, the Mahanadi, and the Ganges-Brahmaputra rivers. The last of those is some 190 miles (300 km) wide, but only about one-third of it lies within India. Traversed by innumerable distributaries, the Ganges delta is an ill-drained region, and the western part within Indian territory has become moribund because of shifts in the channels of the Ganges. Tidal incursions extend far inland, and any small temporary rise in sea level could submerge Kolkata (Calcutta), located about 95 miles (155 km) from the head of the Bay of Bengal. The eastern coastal plain includes several lagoons, the largest of which, Pulicat and Chilka (Chilika) lakes, have resulted from sediment being deposited along the shoreline.

Islands

Several archipelagoes in the Indian Ocean are politically a part of India. The union territory of Lakshadweep is a group of small coral atolls in the Arabian Sea to the west of the Malabar Coast. Far off the eastern coast, separating the Bay of Bengal and the Andaman Sea, lie the considerably larger and hillier chains of the Andaman and Nicobar Islands, also a union territory; the Andamans are closer to Myanmar and the Nicobars closer to Indonesia than to the Indian mainland.