Geology

A.R. Hildebrand, G.T. Penfield, D.A. Kring, M. Pilkington, A. Camargo Zanoguera, S.B. Jacobsen, W.V. Boynton, "Chicxulub crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatan Peninsula, Mexico," Geology, 19:867-871, 1991.

Alan Hildebrand (Geological Survey of Canada, Ottawa, Ontario): "The discovery of the Chicxulub crater and proximal Cretaceous/Tertiary (K/T) ejecta deposits between the Americas has dramatically changed the decade-long K/T debate. The theory that the thin K/T boundary clay contained evidence of an impact large enough to cause the mass extinction at the end of the Cretaceous was first proposed in 1980 (L.W. Alvarez, et al., Science, 208:1095-1108, 1980). Since then it has been the most contentious topic in the geosciences, and, although some interested scientists are still saying that no K/T impact ejecta deposits have been found and that the Chicxulub structure is not a crater, the majority of the community now acknowledges that the evidence for...

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