No killer crater near Cuba....No killer crater near Cuba... Throughout the last decade, geologists have roamed the globe looking form a 65-millin year-old crater -- hard evidence that a huge meteorite meteorite, meteor that survives the intense heat of atmospheric friction and reaches the earth's surface. Because of the destructive effects of this friction, only the very largest meteors become meteorites. knocked the planet silly at the end of the Cretaceous period Cretaceous period (krĭtā`shəs), third and last period of the Mesozoic era of geologic time (see Geologic Timescale, table), lasting from approximately 144 to 65 million years ago. , snuffing out a large fraction of species. Earlier this year, two researchers nominated an island off the southwestern corner of Cuba as a candidate for the long-sought impact site (SN: 4/28-90. p.268). But other g}ologists who visited Cuba in June are advising their colleagues to continue the search elsewhere. Robert S. Dietz Robert Sinclair Dietz (September 14, 1914 – May 19, 1995) was Professor of Geology at Arizona State University. Dietz was a geophysicist and oceanographer who conducted pioneering research along with Harry Hess concerning seafloor spreading as early as 1960 - 1961. and John McHone of Arizona State University Arizona State University, at Tempe; coeducational; opened 1886 as a normal school, became 1925 Tempe State Teachers College, renamed 1945 Arizona State College at Tempe. Its present name was adopted in 1958. in Tempe arranged to visit cuba as attendees of an international convention on marine sciences. While there, they contacted Cuban geologists and examined the purported impact evidence. Many large craters have a central rocky peak, and researchers had proposed Cuba's Isle of Pines as a central peak for the Cretaceous crater. Dietz and McHone could not visit the Islet islet /is·let/ (-lit) an island. islets of Langerhans irregular microscopic structures scattered throughout the pancreas and comprising its endocrine portion. of Pines itself, but they did analyze rock samples collected there by Cuban geologists. The samples showed no evidence of the telltale "shocked" minerals that form violent impacts, they report. Dietz and McHone personally examined another Cuban site mentioned as evidence for an impact: a thick limestone formation containing huge boulders. Proponents of the Cuban crater idea had read descriptions of this formation in geological report, which led them to suggest the huge boulders had been strewn strew tr.v. strewed, strewn or strewed, strew·ing, strews 1. To spread here and there; scatter: strewing flowers down the aisle. 2. there by a nearby impact. Dietz and McHone, however, believe normal weathering of the limestone rock created the boulders. Although the Tempe researchers can't entirely discount the Cuban candidates, they say it's unlikely the meteorite hit there. |
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