Physiography is the study of the relief features of the Earth surface. It is shaped by the geomorphic processes operating below the Earth’s crust (endogenic) as well as above the surface (exogenic). The endogenic and exogenic forces cause physical stresses and chemical actions on earth materials and bring changes in the configuration of the surface of the earth.
India has a long history of its geological evolution. Starting right from the breaking up of Pangea and then the northward march of the Indo – Australian plate towards Eurasian plate, India has undergone several changes in its geology as well as physiography.
Moreover, the complex interaction of several weathering as well as erosional processes and agents, has further shaped the India’s physiography.
- The Indian plate includes Peninsular India and the Australian continental portions.
- The subduction zone along the Himalayas forms the northern plate boundary in the form of continent— continent convergence.
- In the east, it extends through Rakinyoma Mountains of Myanmar.
- The Western margin follows Kirthar Mountain of Pakistan. It further extends along the Makrana coast and joins the spreading site from the Red Sea rift south eastward along the Chagos Archipelago.
- The boundary between Indo-Australian and the Antarctic plate is also marked by oceanic ridge (divergent boundary)
- India was a large island situated off the Australian coast, in a vast ocean. The Tethys Sea separated it from the Asian continent till about 225 million years ago.
- India started her northward journey about 200 million years ago at the time when Pangaea broke. Tibetan block was closer to the Asiatic landmass.
- Indo-Australian plate collided with Eurasian plate about 40-50 Mn years ago causing rapid uplift of the Himalayas (Still rising).
Broadly India is divided into five physiographic regions:
- The Northern and North-eastern mountains
- The Great northern plains
- The Peninsular plateau
- The Coastal plains
- The Islands