Geography

India comprises the bulk of the Indian subcontinent and lies atop the minor Indian tectonic plate, which in turn belongs to the Indo-Australian Plate. India's defining geological processes commenced 75 million years ago when the Indian subcontinent, then part of the southern supercontinent Gondwana, began a north-eastward drift across the then-unformed Indian Ocean that lasted fifty million years. The subcontinent's subsequent collision with, and subduction under, the Eurasian Plate bore aloft the planet's highest mountains, theHimalayas. They abut India in the north and the north-east. In the former seabed immediately south of the emerging Himalayas, plate movement created a vast trough that has gradually filled with river-borne sediment; it now forms the Indo-Gangetic Plain. To the west lies the Thar Desert, which is cut off by the Aravalli Range.

The original Indian plate survives as peninsular India, which is the oldest and geologically most stable part of India; it extends as far north as the Satpura and Vindhya ranges in central India. These parallel chains run from the Arabian Sea coast in Gujarat in the west to the coal-rich Chota Nagpur Plateau in Jharkhand in the east. To the south, the remaining peninsular landmass, the Deccan Plateau, is flanked on the west and east by coastal ranges known as the Western and Eastern Ghats; the plateau contains the nation's oldest rock formations, some of them over one billion years old. Constituted in such fashion, India lies to the north of the equator between 6° 44' and 35° 30' north latitude and 68° 7' and 97° 25' east longitude.