T. Rex and the Crater of Doom
Walter Alvarez is one of the Berkeley scientists responsible for the theory, now well-established, that the dinosaurs perished after a huge asteroid or comet hit the Yucatan Peninsula sixty-five million years ago, setting off a monstrous tsunami and a sequence of disastrous climatic changes. In telling his story, Alvarez explains the way geologists read the earth’s history in rock formations such as those found in the Bottaccione Gorge at Gubbio, Italy.
Establishing the impact theory of dinosaur extinction prompted a shoot-out between the gradualists, who scorn suggestions of sudden violent changes in the earth’s history, and the catastrophists, who emphasize the effects of sudden cataclysms. Alvarez tells this story well.
The discovery of iridium at just the right level in the Gubbio limestone was a crucial step in...
(The entire section is 265 words.)