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Science Frontiers ONLINE No. 15: Spring 1981 |
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Iceland And The Iridium Layer
The high concentration of iridium between the Cretaceous and Tertiary eras (about 65 million years ago) is widely interpreted as indicating a worldwide catastrophe caused by the impact of a comet or meteor. The increase of iridium concentration over normal levels is much higher in northern latitudes, suggesting that the impact point is in this region. But no impact scar of the proper size and age exists. However, if one looks for scabs rather than scars, one finds that Iceland is formed entirely of volcanic rocks younger than the Cretaceous. To Fred Whipple of the Smithsonian Astrophysical Observatory, these facts dovetail nicely. Iceland was form ed by magma welling up from a 100-km hole in the sea floor blasted out by a 10-km meteor.
(Anonymous; "The Blow That Gave Birth to Iceland?" New Scientist, 89:740, 1981.)