Asteroid Theory Backed in Extinction of Dinosaurs

Tiny, glassy particles from Haiti provide new evidence that a huge asteroid struck the Earth about 65 million years ago, killing off the dinosaurs and other life forms, a team of researchers reported last week in the journal Nature. Chemical and structural analysis suggests that the glass blobs were formed from rock by the extreme heat of such an impact, they said.

The impact may have kicked up debris that blocked out sunlight and thereby killed off many plants that dinosaurs ate, some scientists say. Others propose that lethal effects stemmed from acid rain or worldwide forest fires. Still others reject the impact hypothesis and blame the extinctions on volcanic activity and climate changes.

Vulcanologists have previously said that the glass particles could have been formed by volcanic eruptions. But the new study concluded that the blobs could not have been formed in that fashion because they do not contain crystals, they have high calcium concentrations and they contain ratios of elements uncharacteristic of volcanic products.

“I don’t think we have by any means proven it was an impact, but we’ve provided another brick in the wall,” said geologist Michael Arthur of Pennsylvania State University.