Deccan Traps
The Deccan Traps are an extraordinarily large province of igneous rock. The traps consist of massive amounts of ancient volcanic rock dating from around 65 million years ago, at around the same time as the dinosaur extinction. They cover an area of roughtly 193,000 square miles. The sheer magnitude of the traps might give credence to the theory that an abnormality of volcanic activity caused the dinosaur extinction instead of an asteroid. Furthermore, the volcanic matter released during the formation of the traps would have likely caused a cooling, further triggering extinction.