The Deccan Traps are a huge stack of volcanic rocks more than two kilometres (1.2 miles) thick that cover nearly 500,000 square kilometres (200,000 square miles) of west-central India. They were formed by a massive volcanic eruption 60-65 million years ago, which spewed out enough lava to cover Earth three metres (ten feet) deep. The gases released may have changed global climate and contributed to the extinction of the dinosaurs.
Scientists blame the super-sized eruption on a hot spot, a stationary plume of super-hot buoyant rock in the Earth’s interior that forms a volcano when it reaches the surface. Hot spots create island chains as the rock plates forming the Earth’s surface move over them. The Deccan Traps hot spot may have led to the formation of the French island Réunion in the Indian Ocean.
Answered by Vivienne Raper, How It Works contributor.