Evolution: Extinction: What Killed the Dinosaurs?
Evidence for the Volcanism Hypothesis
Lava Flows
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 volcanicactivity for at least 500,000 years leading up to the extinction of the dinosaurs.
Rare Metal
The metal iridium, which is similar to platinum, is very rare on Earth's surface butis more common in asteroids and in molten rock deep within the planet.
Some scientists think the presence of high concentrations of iridiumat the geological layer associated with the dinosaur extinction could be the result ofextremely large-scale volcanic activity.
Fractured Crystals
These crystals, often called "shocked quartz," show a distinctive pattern of fracturingcaused by high-energy impacts or explosions.
Although geologists generally acknowledge that a comet or asteroidimpact would cause these fractures, some scientists conclude that they could also be theresult of volcanic eruptions.
Fossil Record
A gradual decline in the number of dinosaur species would likely mirror an equallygradual 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 locationand interpretation, the fossil record seems to say different things.
A gradual decline in the number of dinosaur species would likelymirror an equally gradual process like climate change caused by global volcanism.
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