Based on the variations in its geological structure and formations, India can be divided into three geological divisions. These geological regions broadly follow the physical features:
- (i) The Penisular Block
- (ii) The Himalayas and other Peninuslar Mountains
- (iii) Indo-Ganga-Brahmaputra Plain.
‘Physiography’ of an area is the outcome of structure, process and the stage of development. The land of India is characterised by great diversity in its physical features. The north has a vast expanse of rugged topography consisting of a series of mountain ranges with varied peaks, beautiful valleys and deep gorges. The south consists of stable table land with highly dissected plateaus, denuded rocks and developed series of scarps. In between these two lies the vast north Indian plain. Based on these macro variations, India can be divided into the following physiographic divisions:
- (1) The Northern and North-eastern Mountains
- (2) The Northern Plain
- (3) The Peninsular Plateau
- (4) The Indian Desert
- (5) The Coastal Plains
- (6) The Islands.
1) The Northern Mountain: It is divided into three groups. They are : (i) The Himalayas (ii) The Trans Himalayas (iii) The Puranchal hills
2) The Northern Plains: The Northern plain is broadly divided into two parts : (a) The Western plain (b) The Ganga-Brahmaputra plain
3) The Peninsular Plateau: Peninsular plateau is a triangular shaped table land. It covers an area of nearly 5 lakh sq.km. It is spread over the states of Gujarat, Maharashtra, Bihar, Karnataka and Andhra Pradesh.
River Narmada divides the peninsular plateau into two parts : The central highlands and Deccan Plateau.
- The central Highlands: It extends from Narmada river and the northern plains. A ravallis is the important mountain which extends from Gujrat through Rajasthan to Delhi.
- The Deccan Plateau: The Deccan plateau is separated by a fault (A fracture in the rock along which rocks have been relatively replaced), from Chota Nagpur plateau. The black soil area in the Deccan plateau is known as Deccan trap. It is formed due to volcanic eruptions. This soil is good for cotton & sugarcane cultivation. The Deccan plateau is broadly divided into: (a) The Western Ghats (b) The Eastern Ghats
4) The Indian Desert: The Indian Desert lies towards the western margin of Aravali Hills. It is also called Thar Desert. It is the ninth largest desert in the world. It spreads over the states of Gujarat and Rajasthan.
5) The Coastal Plains: The coastal plains in India run parallel to the Arabian Sea & Bay of Bengal along the Peninsular Plateau.The western coastal plain is a narrow belt along the Arabian sea of about 10-20km wide. It stretches from Rann of Kachchh to KanyaKumari.
6) The Islands: India has two main groups of Islands. There are 204 islands in Bay of Bengal called as Andaman and Nicobar islands and 43 islands in Arabian Sea called as Lakshadweep islands The Andaman & Nicobar island extend from north to south in Bay of Bengal.