Key Points

Based on geological structure, India is divided into three main divisions: the ancient and rigid Peninsular Block, the young and flexible Himalayas, and the depositional Indo-Ganga-Brahmaputra Plain.

The Peninsular Block is a stable landmass composed of ancient gneisses and granites. It features relict mountains like the Aravallis and rift valleys such as the Narmada and Tapi.

The Himalayas are young, weak, and flexible mountains of tectonic origin. They are still undergoing changes due to geological forces, resulting in faults, folds, and landforms like V-shaped valleys and gorges.

This plain is a geo-synclinal depression formed during Himalayan mountain building. It has been gradually filled with alluvial sediments brought by the Himalayan and Peninsular rivers, with deposits reaching 1,000-2,000 meters deep.

India is divided into six physiographic divisions: The Northern and Northeastern Mountains, The Northern Plain, The Peninsular Plateau, The Indian Desert, The Coastal Plains, and The Islands.

This division comprises the Himalayas and the Northeastern hills, which consist of a series of parallel mountain ranges. The Great Himalayan range is approximately 2,500 km long from east to west.

From north to south, the Northern Plains are divided into four zones: Bhabar (boulder-strewn), Tarai (marshy and swampy), Bhangar (older alluvium), and Khadar (newer alluvium).

The Peninsular Plateau is an irregular triangle and one of the oldest landmasses of India. Its general elevation slopes from west to east, which is indicated by the direction of river flow.

The Peninsular Plateau is broadly divided into three groups based on relief features: The Deccan Plateau, The Central Highlands, and The Northeastern Plateau.

The Western Ghats are continuous and higher in elevation, while the Eastern Ghats are discontinuous, lower, and highly eroded by rivers. They meet each other at the Nilgiri hills.

The highest peak of the Peninsular plateau is 'Anaimudi' (2,695 m), located on the Anaimalai hills of the Western Ghats. The second highest peak is Dodabetta (2,637 m) on the Nilgiri hills.

Located to the northwest of the Aravali hills, this is an arid region with low rainfall (below 150 mm per year). It is characterized by sand dunes like barchans, and the Luni is its most significant river.

The western coast is a submerged coastal plain, making it narrow and providing natural conditions for ports. The Malabar coast is known for its 'Kayals' (backwaters).

The eastern coast is an emergent and broader plain. It is characterized by well-developed deltas formed by east-flowing rivers like the Mahanadi, Godavari, Krishna, and Kaveri.

These islands in the Bay of Bengal are considered an elevated portion of submarine mountains. The Andaman in the north and Nicobar in the south are separated by the Ten Degree Channel.

These islands in the Arabian Sea are of coral origin. The entire group consists of approximately 36 islands, with Minicoy being the largest.