Extraterrestrial Cause for the Cretaceous-Tertiary Extinction

@article{Alvarez1980ExtraterrestrialCF,
  title={Extraterrestrial Cause for the Cretaceous-Tertiary Extinction},
  author={L. W. Alvarez and W. Alvarez and F. Asaro and H. Michel},
  journal={Science},
  year={1980},
  volume={208},
  pages={1095 - 1108}
}
Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of… Expand
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