The argument for extinction by volcanoes The Earth's crust is made up of layers of rock. The deeper the layer, the longer ago the layer was created. Fossils of dinosaurs are only found in layers of rock formed between about 250 and 65 million years ago.

Dinosaur fossils are not found after about 65 million years ago. Dinosaur fossils start to gradually become rarer in rocks from about 72 million years ago. Then they become increasingly rare during the final 300 thousand years before the dinosaurs became extinct.

Fossils show that during that time, mammals were rapidly evolving

In North India there is a region of volcanic rock 2000 metres deep covering about half a million square kilometres. When it was originally formed, it would have been about three times larger. This region is now known as the Deccan Traps.

The rock leaked out as magma from deep within the Earth between about 68 and 60 million years ago. Most of rock in the Deccan Traps leaked out about 66 million years ago. This period may have lasted less than 30,000 years.

The amount of magma produced at this time would have been about 1 million times greater than the eruption that destroyed Pompeii.

The dinosaurs start to become extinct about the same time the Deccan Traps started to form. The final extinction of the dinosaurs happened very close to the time the Deccan Traps event was most active. Even far, far smaller volcanoes can cause short-term climate change. The Deccan Traps would have caused major climate change. These changes would have been greatest during the time the dinosaurs became extinct. Therefore the dinosaurs could not cope with these changes and became extinct.