Dinosaur Deaths

By George Grow

This is the VOA Special English SCIENCE REPORT.

Scientists are preparing to drill into a huge hole on the Yucatan Peninsula in eastern Mexico. The hole was caused by a large object that fell from space. The scientists plan to test rocks they believe were present when the asteroid hit Earth about sixty-five million years ago. They hope to find clues about what led to the death of dinosaurs and other ancient creatures.

Buck Sharpton of the University of Alaska in Fairbanks is organizing the drilling project at the hole. He spoke last month at a meeting of the American Geophysical Union in San Francisco, California.

Drilling is to start in June about eighty kilometers south of the Mexican city of Merida. The huge hole is estimated to be about two-hundred kilometers wide. Mr. Sharpton and his team plan to drill about two kilometers down into the hole

Twenty years ago, research scientists proposed the theory that the crash of an asteroid or comet created a large cloud of dust. They said the cloud blocked light from the sun from reaching Earth. This sharply cooled the weather. The cold weather and lack of sun killed plants and other food eaten by dinosaurs and other creatures. Soon, they were all dead.

Researchers had proposed this idea after finding large amounts of the element iridium. They found the iridium in an area of ground that was formed about the same time dinosaurs died out. Iridium is rare on earth. But large amounts of it are found in asteroids and comets.

Scientists from the United States and Mexico found evidence about ten years ago that an asteroid caused the huge hole in Mexico. But some scientists say that asteroid was not big enough to create a deadly cloud of dust. However, drilling in the area has led to the discovery of carbonate and sulfur rocks.

The new theory is that the asteroid hit with such force it released poisonous chemicals. The release of carbon dioxide and sulfur gas created acid rain, and severe air and water pollution. The sulfur also created deadly sulfuric acid in any water supplies on Earth. Dinosaurs and other ancient creatures were poisoned.

The scientists will drill deep into the hole to test the rocks that remain after the asteroid hit. They hope to better understand any chemical reactions which would have affected the environment.

This VOA Special English SCIENCE REPORT was written by George Grow.