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... Science Frontiers ONLINE No. 6: February 1979 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Venus Has Uncertain Pedigree The five instrumented Pioneer probes that plunged into the thick Venusian atmosphere in late 1978 discovered unexpectedly large quantities of the isotope argon-36. The significance of argon-36 is that it is supposed to be primordial argon; that is, an argon isotope formed when the solar system was born. Since argon-36 is radioactive, most of the original supply of this isotope should have disintegrated and disappeared over the 4-billion-year history of the solar system. Indeed, the atmospheres of earth and Mars have much, much smaller quantities of argon-36 than Venus. Venus, therefore, may have had an origin different from that of earth and Mars -- either a much more recent birth (such that the argon-36 has not all disintegrated), or an altogether different kind of origin in which more argon-36 was created than was the case for earth and Mars. (Anonymous; "Venus Probes Solar System Birth," New Scientist, 80:916, 1978.) From Science Frontiers #6 , February 1979 . 1979-2000 William R. Corliss ...
Terms matched: 1 - Score: 89 - 15 May 2017 - URL: /sf006/sf006p03.htm
... Science Frontiers ONLINE No. 8: Fall 1979 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Old tektites in young sediments?A curious little geological debate now going on concerns the Australian tektites. The age of formation for these tektites, as determined by both fissiontrack and potassium-argon dating lies between 700,000 and 860,000 years. Geological evidence, however, suggests that the tektites fell only 7,000 to 20,000 years ago -- a substantial discrepancy. Surely, say some, these old tektites were washed out of some equally old deposits and transported to the young strata where they now reside. Not so, say Australian geologists, because most of these tektites are found in areas devoid of outcroppings 700,000 years old. Furthermore, the rather fragile tektites show little signs of wear, as they should if transported by flood waters for long distances. These and other geological facts militate against the 700,000-year date. Geologists have questioned the two dating techniques, while geophysicists think the geological evidence is shaky. (Chalmers, R.O ., et al; "Australian Microtektites and the Stratigraphic Age of the Australites," Geological Society of America, Bulletin, 90:508, 1979.) Comment. It is important to resolve this issue because the dating methods employed are crucial to the now-dominant theory of plate tectonics. In particular, the 700,000-year figure seems to represent a major crisis in biological and geological history. Reference. We expand on the ...
Terms matched: 1 - Score: 14 - 15 May 2017 - URL: /sf008/sf008p10.htm
... Science Frontiers ONLINE No. 87: May-Jun 1993 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Giant impact-wave deposit along u.s . east coast Along the shore from North Carolina to Maryland and also into Chesapeake Bay, deep-sea drillers have charted the Exmore Boulder Bed. No minor deposit this; it is is over 60 meters thick in places and covers more than 15,000 square kilometers. In the bed are found boulders (up to 2 meters in diameter), cobbles, pebbles, and traces of tektite glass and shocked quartz. The youngest microfossils date from the Eocene, and argon dating of the ejecta yield a date of 35.5 million years, which correlates with the North American tektite strewn field. C.W . Poag et al interpret this boulder bed as follows: "On the basis of its unusual characteristics and its stratigraphic equivalence to a layer of impact ejecta at Deep Sea Drilling Project (DSDP) Site 612 (New Jersey continental slope), we postulate that this boulder bed was formed by a powerful bolidegenerated wave train that scoured the ancient inner shelf and coastal plain of southeastern Virginia. The most promising candidate for the bolide impact site (identified on seismic reflection profiles) is 40 km north-northwest of DSDP Site 612 on the New Jersey outer continental shelf." (Poag, C. Wylie, et al; "Deep Sea Drilling Project Site 612 Bolide Event: New Evidence of a Late Eocene Impact-Wave Deposit and a Possible Impact Site, U ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf087/sf087g12.htm
... that detailed five different lines of evidence that are inconsistent with the claim by L.A . Frank and J.B . Sigwarth that the earth is bombarded daily by 30,000 house-size icy comets. If such bombardment has really been occurring, scientists would have to rethink the origins of the earth's oceans, terrestrial life, and the formation of the solar system. No wonder the icy-comet hypothesis is strongly challenged! Three of the more interesting points made by this group of papers are as follows: Our moon could not escape the icy-comet bombardment. Roughly 1,000 craters 50 meters in diameter and splashes of debris 150 meters in diameter must occur each. There is no evidence that the moon is thus afflicted. Comets also carry the noble gases argon, krypton, and xenon. These gases should accumulate in the atmosphere as the comets disintegrate. The amounts of these gases actually measured are 10,000 times less than those the postulated bombardment would produce. The icy comets should break up near the earth and produce clouds of ice crystals. Sunlight reflected from such 30-ton clouds would be brighter than Venus and easily visible before they disperse. Such objects are rarely seen, implying that small icy comets do not exist in the numbers claimed. Preceding this series of five papers is one by Frank and Sigwarth in which they describe their detection of atomic oxygen trails near earth. These they attribute to small icy comets. (Various; "Looking for Small Comets -- None Found," Geophysical Research Letters, 24:2429 ++ ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf118/sf118p14.htm
