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Views of Terrestrial Craters

by Calvin J. Hamilton

Barringer Meteor Crater, Arizona

  • 35°02'N, 111°01'W; diameter: 1.186 kilometers (.737 miles); age: 49,000 years
    The origin of this classic simple meteorite impact crater was long the subject of controversy. The discovery of fragments of the Canyon Diablo meteorite, including fragments within the breccia deposits that partially fill the structure, and a range of shock metamorphic features in the target sandstone proved its impact origin. Target rocks include Paleozoic carbonates and sandstones; these rocks have been overturned just outside the rim during ejection. The hummocky deposits just beyond the rim are remnants of the ejecta blanket. This aerial view shows the dramatic expression of the crater in the arid landscape. (Courtesy of D. Roddy and LPI)

    Chicxulub, Yucatan Peninsula, Mexico

  • 21°20'N, 89°30'W; diameter: 300 km; age: 64.98 million years
    This three-dimensional map of local gravity and magnetic field variations shows a multiringed structure called Chicxulub named after a village located near its center. The impact basin is buried by several hundred meters of sediment, hiding it from view. This image shows the basin viewed obliquely from approximately 60° above the surface looking north, with artificial lighting from the south. The image covers 88 to 90.5° west longitude and 19.5 to 22.5° north latitude (ca. 260 x 330 km). NASA scientists believe that an asteroid 10 to 20 kilometers (6 to 12 miles) in diameter produced this impact basin. The asteroid hit a geologically unique, sulfur-rich region of the Yucatan Peninsula and kicked up billions of tons of sulfur and other materials into the atmosphere. Darkness prevailed for about half a year after the collision. This caused global temperatures to plunge near freezing. Half of the species on Earth became extinct including the dinosaurs. (Courtesy of V. L. Sharpton, LPI)

    Copyright © 1994, 1995, 1996 by Calvin J. Hamilton. All rights reserved.