Evidence for the Volcanism Hypothesis
Immense lava flows cover nearly 200,000 square miles of the Deccan region of India,
reaching depths of more than 6,500 feet in places.
Lava flows like these provide evidence of a rash of volcanic
activity for at least 500,000 years leading up to the extinction of the dinosaurs.
The metal iridium, which is similar to platinum, is very rare on Earth's surface but
is more common in asteroids and in molten rock deep within the planet.
Some scientists think the presence of high concentrations of iridium
at the geological layer associated with the dinosaur extinction could be the result of
extremely large-scale volcanic activity.
These crystals, often called "shocked quartz," show a distinctive pattern of fracturing
caused by high-energy impacts or explosions.
Although geologists generally acknowledge that a comet or asteroid
impact would cause these fractures, some scientists conclude that they could also be the
result of volcanic eruptions.
A gradual decline in the number of dinosaur species would likely mirror an equally
gradual cause of their ultimate extinction. Conversely, a sudden "now you see them,
now you don't" end to the dinosaurs implies a catastrophic cause. Depending on location
and interpretation, the fossil record seems to say different things.
A gradual decline in the number of dinosaur species would likely
mirror an equally gradual process like climate change caused by global volcanism.