This Deccan trap occupying the one-sixth of Indian landmass happens to be the largest known volcanism on earth's surface, but its origin has been shrouded in the history. The Indian subcontinent separated from Antarctica about 135 million years ago, collided with Eurasian plate some 35 million years ago producing the mighty Himalayas by upliftment. Frictional heating of these moving plates partly shelved the crest that led to the upwalling of the magma thus giving birth to the Deccan trap. Thereafter, a long period of erosion on the horizontally laid lava flows explains their present day appearances. Water action has carved out river valleys and their tributary valleys leaving the harder material as residual mountain ranges, the Sahyadri.