Word: alvarez
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
This startling scenario, proposed in 1980 by the late Nobel laureate Luis Alvarez and his son Walter, ignited a scientific debate that still rages today. Opponents of the theory, notably paleontologists, blame the Great Extinction on climatic changes possibly brought on by volcanic activity. If the Alvarezes were correct, they ask, where is the smoking gun? Where is the crater...
...Alvarezes analyzed this clay in the late 1970s and showed it had a far higher content of the rare element iridium than ordinarily found in the earth's crust. It was this discovery that led Luis Alvarez to his momentous - insight. Comets and asteroids have high iridium content, he reasoned, and the clay layer could have been formed by the worldwide fallout of the material vaporized when an errant asteroid or, as most scientists now suspect, a giant comet smacked into the earth...
This week, at an astronomy conference in Flagstaff, Ariz., scientists will add an intriguing twist to the Alvarez scenario. Their interpretation is based on new evidence that the Cretaceous-clay boundary actually consists of two parts: a thin layer overlying a more substantial one. To Eugene Shoemaker, of the U.S. Geological Survey and a co-author of the report, two layers indicate not one but two impacts...
Margarita Otero-Alvarez, principal of the Longfellow Elementary School in Cambridge says she agrees to some extent. Many teachers are opposed to the measure because they have always planned to have their summers free, she says. "In general, I get a negative response [from the staff]," she says...
...Otero-Alvarez adds that resistance to the measure stems more from lack of information than anything else since the bill is still in its early stages and has yet to be discussed fully be either the State House or Senate...