Deccan Plateau: Geology and Resources Explained for UPSC SSC

Geological Formation

The Deccan Plateau is one of the oldest and most stable landmasses on Earth. Its formation dates back to the Cretaceous period, approximately 66 million years ago. This period saw massive volcanic eruptions, known as the Deccan Traps. These eruptions covered a vast area of peninsular India with layers of basaltic lava. The lava flows were extensive, reaching thicknesses of up to 2,000 meters in some regions, particularly along the Western Ghats. The plateau is primarily composed of igneous rocks, specifically basalt, which gives the region its characteristic black soil.

The geological history of the Deccan Plateau is linked to the movement of the Indian plate. As the Indian plate drifted northwards after breaking away from Gondwana, it passed over a volcanic hotspot, leading to the Deccan Traps. This geological event significantly shaped the topography and soil composition of the region. The plateau is bordered by the Western Ghats in the west, the Eastern Ghats in the east, and the Satpura, Maikal, and Mahadeo ranges in the north. Its average elevation ranges from 600 meters in the north to 1,000 meters in the south.

Major Physiographic Divisions

The Deccan Plateau can be broadly divided into several physiographic regions. The most prominent are the Maharashtra Plateau, the Karnataka Plateau, and the Telangana Plateau. The Maharashtra Plateau, located in the northwestern part, is characterized by its extensive basaltic lava flows and black cotton soil, known as Regur. This region is drained by rivers like the Godavari, Bhima, and Krishna.

The Karnataka Plateau, also known as the Mysore Plateau, lies to the south of the Maharashtra Plateau. It is composed of ancient crystalline rocks and is rich in mineral resources. The highest peak in this region is Mullayanagiri in the Baba Budan Hills. The Telangana Plateau, situated in the eastern part, is drained by the Godavari and Krishna rivers. It is generally undulating and composed of granite and gneiss. These divisions reflect variations in underlying geology, elevation, and drainage patterns across the vast plateau.

Mineral Resources

The Deccan Plateau is a storehouse of valuable mineral resources, making it economically significant. The Karnataka Plateau, in particular, is rich in iron ore, manganese, gold, and bauxite. The Kolar Gold Fields, though now largely defunct, were historically a major source of gold. Iron ore deposits are found in districts like Bellary and Chikmagalur. Manganese deposits are also significant in this region. The Chotanagpur Plateau, which is often considered an extension of the Deccan Plateau in the northeast, is exceptionally rich in coal, iron ore, mica, and bauxite.

Other parts of the Deccan Plateau also contribute to India's mineral wealth. Bauxite, the primary ore for aluminum, is found in various locations. Limestone, used in cement production, is abundant. Granite and other building stones are extensively quarried. The presence of these diverse minerals has led to the development of various industries, including steel, cement, and aluminum, across the plateau region.

Agricultural Significance

Agriculture is a dominant economic activity on the Deccan Plateau, largely influenced by its unique soil types. The black cotton soil (Regur) found in the northwestern Deccan, formed from weathered basalt, is highly fertile and retains moisture well. This makes it ideal for cultivating cotton, sugarcane, and jowar (sorghum). The central and southern parts of the plateau, with their red and yellow soils derived from crystalline rocks, support crops like groundnuts, pulses, and ragi (finger millet).

Rainfall patterns also dictate agricultural practices. The plateau experiences varying rainfall, with the Western Ghats creating a rain shadow region in much of the interior. This often leads to reliance on irrigation, particularly from rivers like the Godavari, Krishna, and Cauvery. Major dams and irrigation projects, such as the Nagarjuna Sagar Dam on the Krishna River, play a crucial role in supporting agriculture and ensuring food security in the region. The diverse agro-climatic conditions allow for a wide range of crops to be grown.

Important Keywords Explained

Deccan Trapsplace

A large igneous province of west-central India, one of the largest volcanic features on Earth. It consists of multiple layers of solidified flood basalt that together are more than 2,000 meters thick, covering an area of 500,000 square kilometers. Formed during the late Cretaceous period.

Regur Soilconcept

Also known as Black Cotton Soil, it is characteristic of the Deccan Plateau. Formed from the weathering of basaltic rocks, it is rich in clay minerals, highly fertile, and has excellent moisture-retention capacity. Ideal for cotton cultivation.

Gondwanaconcept

A supercontinent that existed from the Neoproterozoic (about 550 million years ago) until the Jurassic (about 180 million years ago). It included most of the landmasses in today's Southern Hemisphere, including Antarctica, South America, Africa, Madagascar, Australia, and the Arabian Peninsula and Indian subcontinent.

Additional Facts & Context

• The total area of the Deccan Plateau is approximately 500,000 square kilometers.
• The average annual rainfall in the rain shadow region of the Deccan Plateau is often less than 60 cm.
• The Godavari River, the longest river in Peninsular India, flows for about 1,465 kilometers.
• The Krishna River is the second-largest east-flowing peninsular river, with a length of about 1,400 kilometers.
• The Deccan Plateau is part of the larger Peninsular Plateau of India, which is one of the oldest landforms.