Mexico's Chicxulub crater is believed to be the site of a meteorite impact so immense that the resulting environmental changes caused or greatly contributed to the mass extinction 65 million years ago which the dinosaurs did not survive; other meteorite impacts also may have contributed to the mass extinction. In 1908 in the Tunguska Basin in Siberia a meteor that was probably a stony asteroid about 100 ft (30 m) in diameter completely disintegrated before hitting the ground, so no crater was formed; however, all the trees were flattened and wildlife killed in an area 30 mi (50 km) in diameter, more than half the size of Rhode Island. A meteorite estimated to weigh 60 tons rests where it was discovered, near Grootfontein, Namibia. Among the exhibits at the Hayden Planetarium in New York City are three large meteorites brought from Greenland by R. E. Peary (one, called Ahnighito, weighing 361/2 tons) and the conical Willamette meteorite, weighing about 14 tons, found (1902) near Portland, Oreg. In N Mexico a number of meteorites have been found weighing a ton or more each. Siderites weighing more than a ton have been discovered in Brazil, Argentina, and Australia.
Sections in this article:
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Astronomy: General