Geography · Ch 2 — Structure and Physiography
The Peninsular Plateau
The Peninsular Plateau
The photograph shows a stretch of the Peninsular plateau that has been stripped of its soil cover and cut into by relentless erosion. What you see is not a smooth, table-like surface but a broken, uneven terrain — deep gullies and ravines slice through the ground, exposing bare rock in several places. The landscape appears harsh and denuded, with little to no vegetation holding the surface together. This is the visual signature of a plateau that has been dissected over millions of years by running water.
The image is meant to correct a common mental picture. When we say "plateau," we often imagine a flat, elevated tableland. But the Peninsular plateau is an ancient landmass — one of the oldest and most stable parts of India — and its long geological history has left it heavily weathered and eroded. The ravines and bare rocky structures you see in the photograph are exactly the kind of features the chapter lists as typical of this region: tors, spurs, hummocky hills, and wall-like quartzite dykes. The photograph captures the dissected nature of the plateau, showing how uplift and faulting, followed by prolonged denudation, have produced a relief that is far from uniform.
There is a specific regional connection here. The text mentions that the northwestern part of the plateau has a complex relief of ravines and gorges, citing the Chambal ravines of Bhind and Morena as well-known examples. The photograph illustrates precisely this kind of terrain — the deep, branching gullies that form when soft, loose soil is washed away by seasonal streams, leaving behind a scarred, almost badland-like surface. So the image is not just a generic landscape shot; it is a concrete example of the "complex relief" the chapter describes, and it ties the abstract idea of denudation to a real, recognisable landform. …
The Peninsular Plateau is the oldest and most stable landmass of India, rising from about 150 m above the river plains to an elevation of 600–900 m. It forms an irregular triangle, and its outer limits are marked by the Delhi ridge in the northwest (an extension of the Aravalis), the Rajmahal hills in the east, the Gir range in the west, and the Cardamom hills in the south. A detached extension of this plateau also appears in the northeast as the Shillong and Karbi-Anglong plateaus.
The plateau is actually a series of smaller flat-topped plateaus, called patland plateaus, which include the Hazaribagh plateau, the Palamu plateau, the Ranchi plateau, the Malwa plateau, the Coimbatore plateau, and the Karnataka plateau. The general slope of the plateau runs from west to east, a fact confirmed by the direction of river flow. Most Peninsular rivers flow eastward and drain into the Bay of Bengal, while a few flow westward into the Arabian Sea. The east-flowing rivers typically develop deltas and estuaries at their mouths, whereas the west-flowing rivers, being shorter and swifter, generally do not form such features.
Several distinctive physiographic features mark this region: tors (isolated rocky pinnacles), block mountains, rift valleys, spurs, bare rocky structures, series of hummocky hills, and wall-like quartzite dykes. These quartzite dykes are particularly significant because they offer natural sites for water storage. The western and northwestern parts of the plateau are covered extensively by black soil.
The plateau has undergone repeated phases of upliftment and submergence, accompanied by crustal faulting and fractures. The Bhima fault deserves special mention because of its recurrent seismic activity. These spatial variations have created diversity in the relief of the plateau. The northwestern part, for instance, has a complex relief of ravines and gorges, the most well-known being the ravines of Chambal, Bhind, and Morena.
Based on prominent relief features, the Peninsular plateau is divided into three broad groups: the Deccan Plateau, the Central Highlands, and the Northeastern Plateau.
The Deccan Plateau
The Deccan Plateau is bordered by the Western Ghats in the west, the Eastern Ghats in the east, and the Satpura, Maikal, and Mahadeo hills in the north. The Western Ghats are known by different local names: Sahyadri in Maharashtra, Nilgiri hills in Karnataka and Tamil Nadu, and Anaimalai and Cardamom hills in Kerala.
The Western Ghats are comparatively higher in elevation and more continuous than the Eastern Ghats. Their average elevation is about 1,500 m, with height increasing from north to south. Anaimudi (2,695 m), the highest peak of the Peninsular plateau, is located on the Anaimalai hills of the Western Ghats, followed by Dodabetta (2,637 m) on the Nilgiri hills. Most Peninsular rivers originate in the Western Ghats.
The Eastern Ghats, in contrast, are discontinuous and low hills, highly eroded by rivers such as the Mahanadi, the Godavari, the Krishna, and the Kaveri. Important ranges here include the Javadi hills, the Palconda range, the Nallamala hills, and the Mahendragiri hills. The Eastern and Western Ghats meet at the Nilgiri hills.
The Central Highlands
The Central Highlands are bounded to the west by the Aravali range. The Satpura range, formed by a series of scarped plateaus on the south, lies at an elevation of 600–900 m above mean sea level and forms the northernmost boundary of the Deccan plateau. It is a classic example of relict mountains — highly denuded and forming discontinuous ranges.
The extension of the Peninsular plateau can be traced as far as Jaisalmer in the west, where it is covered by longitudinal sand ridges and crescent-shaped sand dunes called barchans. This region has undergone metamorphic processes in its geological history, as evidenced by the presence of metamorphic rocks such as marble, slate, and gneiss.
The general elevation of the Central Highlands ranges between 700–1,000 m above mean sea level, and it slopes towards the north and northeast. Most tributaries of the Yamuna originate in the Vindhyan and Kaimur ranges. The Banas is the only significant tributary of the Chambal that originates from the Aravalli in the west. An eastern extension of the Central Highlands is formed by the Rajmahal hills, to the south of which lies the Chotanagpur plateau, a large reserve of mineral resources.