2/8/96

Mitch Emmons (emmonmb@mail.auburn.edu)

AU GEOLOGIST STUDIES METEORITE'S EFFECT ON DINOSAUR EXTINCTION

AUBURN -- After exploring and studying Mexico's Yucatan peninsula, Auburn University geologist says he's convinced that dinosaurs were wiped out 65 million years ago by a giant meteorite that struck earth.

David King Jr., an associate professor in the Department of Geology, is among those scientists who believe the collision in Mexico --which spewed gases and debris throughout the atmosphere, causing wildfires and choking off the sunlight -- directly lead to the dinosaurs' demise.

"There were a lot of changes happening on the earth 65 million years ago," King said. "Different animals were under a great deal of stress from these changes. One of the changes was that this meteorite struck the earth, threw a lot of debris into the atmosphere, made it much colder for a long period of time . . . caused acid rain, wildfires. It was the most catastrophic event that the earth has experienced at least within the last 65 million years."

The collision also caused an earthquake that would today register about 13 on the Richtor scale, King added.

"That's something we (humans) have never experienced," he said. "The energy released at impact is estimated to equal 114 million megatons of TNT -- which accounts for the spread of ejecta for hundreds of miles."

The debris crater being studied by King and his colleagues through the Planetary Society of Pasadena, Calif., is located in Belize, Central America. The crater is about 200 miles from the actual site of the meteorite's impact, King said. But it is the largest known crater on Earth -- and the largest to have formed in our inner solar system within the past three billion years.

Scientists estimate that the meteorite was about six miles in diameter. At impact, it created a crater some 115 miles in diameter.

"Ejecta deposits once covered much of the Yucatan region of Mexico, northern Guatemala and Belize," King said.

But the impact crater and most of the ejecta now are buried -- except for the recent discovery of the crater in Belize, where it has been protected by dense rain forest vegetation.

"It is very rare for geologists to see this type of finding," King said.

The Planetary Society team is the first to observe and collect samples of the actual ejecta debris, according to King. The group, he added, found automobile-sized boulders which had been hurled some 200 miles by the meteorite's impact.

Smaller stones, he said, show evidence of thermal alteration, impact shock and deep scratching and grooving.

The research group plans further studies in Belize and in Italy, where ash and dust layers from the impact's vapor cloud have been discovered, King added.

King said he plans to focus much of his study on Alabama, where the results of a huge tidal wave produced by the meteorite's crash are preserved in sediments along Alabama's coastal plain.

His research also may lead to a new geology course at AU on Alabama dinosaurs, he said.

feb96AU-dinosaurs

CONTACT: King, 334/844-4882.