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A search for evidence of large body Earth impacts associated with biological crisis zones in the fossil recordThe natural history of the Earth, how the present plant and animal species developed, how others completely died out, etc., was studied. The rock strata sampled and studied were at the time of deposition at sea bottom. It was found that, exactly at the stratigraphic level corresponding to the extinction, a thin clay layer was greatly enriched in the the rare element iridium. It was hypothesized that the excess irridium at the boundary came from a large steroid like object that hit the earth, and that the impact of this object threw up a dust cloud dense enough and long lasting enough to bring about the extinction of a wide variety of plants and animals, producing the unique break in in the fossil record, the cretaceous-tertiary boundary. The same iridium and platinum metals enrichement are found in a thin clay layer that corresponds with the boundary as difined by sudden radical changes in plant populations. The irridium enrichement is confirmed at other fresh water origin rites in the Raton Basin.
Document ID
19850018256
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Orth, C. J.
(Los Alamos Scientific Lab. NM, United States)
Gilmore, J. S.
(Los Alamos Scientific Lab. NM, United States)
Knight, J. D.
(Los Alamos Scientific Lab. NM, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1985
Publication Information
Publication: Lunar and Planetary Inst. 16th Lunar and Planetary Sci. Conf.
Subject Category
Space Biology
Accession Number
85N26567
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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