Very significant enhancements of the element iridium have been observed in association with the Cretaceous/ Tertiary boundary in marine sediments laid down 65 m.y. ago and subsequently uplifted above the ocean's surface. If our hypothesis for the origin of the iridium and the cause of the Cretaceous/Tertiary life extinctions (the asteroid-impact theory) (Alvarez et al., 1980) is correct, the Ir anomaly should be associated with the Cretaceous/ Tertiary boundary region wherever it is intact. The present work was undertaken to search for the Ir anomaly in a deep-sea-drilling core, in order to check this aspect of the asteroid-impact theory.
Supplement to: Michel, Helen V; Asaro, Frank; Alvarez, Walter; Alvarez, Luis W (1981): Distribution of iridium and other elements near the Cretaceous/Tertiary boundary in Hole 465A: Preliminary results. In: Thiede, J; Vallier, TL; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 62, 847-849, doi:10.2973/dsdp.proc.62.139.1981
