Big History, Small World: From the Big Bang to You by Stokes Brown Cynthia

Author:Stokes Brown, Cynthia [Stokes Brown, Cynthia]
Language: eng
Format: epub
Publisher: Berkshire Publishing Group
Published: 2018-11-13T00:00:00+00:00

Walter Alvarez: Detective of the Crater of Doom

A geologist of Spanish descent, Alvarez is widely known as the man who discovered what wiped out the dinosaurs.

Walter Alvarez (b. 1940) is a retired professor in the Earth and Planetary Science Department at the University of California at Berkeley. He is known for the theory that an asteroid impact caused the great extinction of 66 million years ago, which finished off the dinosaurs.

Walter was born in Berkeley, California. His father, Luis Alvarez, was a Nobel Prize winner in physics who thought geology was not an interesting science but later changed his mind. Walter’s mother, Geraldine, took him and his sister on train rides through the spectacular American West, lent him his first rock hammer, and showed him places in the Berkeley hills where he could collect minerals.

Alvarez chose to attend Carlton College in Minnesota, where he received his B.A. in geology when he was twenty-one. He went to Princeton University for his Ph.D. in geology. There he enjoyed outdoor adventures in the Caribbean while doing his research. In 1965 he married Milly Millner, a graduate student in psychology who also loved hiking and camping.

Alvarez first worked for an oil company, looking for oil in the Netherlands and Libya. Next he used a fellowship to study volcanoes near Rome with archaeologists before he became a researcher at Lamont-Doherty Geological Observatory of Columbia University, near New York City.

Alvarez fell in love with Italy during his fellowship there. During the summers he and Milly returned to Gubbio, a medieval town north of Rome in the Apennine Mountains. The mountains nearby had wonderful cliffs of limestone that contained a continuous record of Earth history for 100 million years. The limestone had been deposited in the deep ocean with little disturbance by erosion. Alvarez and his geologist friends realized that these limestones provided one of the best historical sequences in the world, a perfect place to study the history of magnetic reversals.

Near Gubbio, Alvarez noticed that right at the 66-million-year boundary, between the layers dated before 66 million years ago and those after that date, lay a narrow band of clay (about half an inch thick) with no microfossils of any organisms. Further analysis revealed that this clay contained iridium, an element that is not common on Earth but is relatively common in asteroids. Further research revealed this iridium layer at many sites around Earth, always at the 66 million-year boundary.

Alvarez solicited the assistance of his father, the physicist, and together they proposed, in 1980, the hypothesis that the dinosaurs had died off as a result of the impact of a monster asteroid crashing into Earth. (By this time Alvarez had moved back to Berkeley to teach at the University of California.)

Most geologists met this proposal with skepticism and even scorn. Who could imagine such a thing? There wasn’t even a known crater the right size at the right time.

Geologists persuaded by the impact theory didn’t give up. They realized that the crater might be underwater and that it would have caused huge ocean waves, called tsunamis.

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