No. 18: Nov-Dec 1981
Kyte et al have discovered a 2.3-millionyear-old sedimentary layer under the Antarctic Ocean that contains iridium and gold concentrations comparable to those in the Cretaceous-Tertiary boundary. The noble metals are mostly contained in millimeter-sized grains that resemble ablation debris from a large extraterrestrial object. Unlike the Cre taceous-Tertiary episode, however, the newly found layer is not accompanied by evidence of mass biological extinctions.
(Kyte, Frank T., et al; "High Noble Metal Concentrations in a Late Pliocene Sediment," Nature, 292:417, 1981.)
Comment. Perhaps those paleontologists who deny the existence of sudden biological extinctions at the CretaceousTertiary boundary are correct and something else besides catastrophism impacted terrestrial life at that juncture.
Reference. The implications of iridium "spikes" are found in Category ESB1 in our Catalog: Anomalies in Geology. To order, go to: here.