November 8, 2009
For a long time now the Mexicans have got it in the neck for being home to the crater formed by the object that killed off the dinosaurs. But it seems the real culprit might lie thousands of miles to the east. According to Sankar Chatterjee of Texas Tech University, the Shiva basin off the coast of India could be the largest, multi-ringed impact crater the world has ever seen and may have been responsible for killing the dinosaurs off 65m years ago. "If we are right, this is the largest crater known on our planet," Chatterjee said. "A bolide [projectile] of this size, perhaps 40 kilometres in diameter creates its own tectonics." By contrast, the object that struck the Yucatan Peninsula was between 8 and 10 kilometres wide. The Shiva impact would have vapourised the Earth's crust at the point of collision, leaving nothing but ultra-hot mantle material to well up in its place. It is also likely to have enhanced the nearby Deccan Traps volcanic eruptions that covered much of western India and to have broken the Seychelles islands away from the Indian tectonic plate, and sent them drifting toward Africa.