HIDDEN deep below the flat scrub land along Mexico's Yucatan peninsula and the tranquil blue sea offshore is the giant imprint of a cosmic catastrophe.
Millions of years before humans existed, a huge meteorite measuring about six miles across and weighing perhaps billions of tons crashed into the Earth. It left one of the biggest craters ever made in the planet and probably caused a global environmental disaster, shrouding the earth in a dense cloud of dust that blocked out sunlight and sent temperatures plummeting.
Invisible to the millions of tourists crossing the Yucatan each year to visit its famous Maya ruins, the Chicxulub crater (pronounced CHICH-oo-loop) is now being studied by a British-led team of scientists who believe it might explain why the dinosaurs suddenly became extinct. The scientists, led by Mike Warner of London University's Imperial College, are excited because the age of the crater - about 65 million years - coincides with a period in which hundreds of species, including the dinosaurs, suddenly died out. "It's extremely likely that the meteorite impact was linked to the many plants and animals which became extinct at the same time as the dinosaurs," Mr. Warner said in a telephone interview. "But making a causal link to the dinosaurs is difficult. You can say it's quite likely, but it's very hard to make a firm link." Warner and his team say their study of the Chicxulub crater, named after the small Yucatan fishing port near to its center, might give them hard evidence. One of the most important issues is the crater's size. The bigger it is, the more likely it is that the impact was to blame for the mass extinctions. The top estimates put the crater at 180 miles across and the lowest at 115 miles, so the team is placing measuring equipment at 20 sites along lines drawn across the basin of the crater to determine its true dimensions. The highly sensitive equipment picks up shock waves from the frequent small earthquakes that ripple across Mexico several times a month. Depending on how the waves are transmitted through the rock deep below the earth, scientists can draw conclusions about the crater's structure and size. …