Geological Truisms Questioned

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first_imgNothing is a constant in scientific theories.  Popular ideas often wind up historical anecdotes.  What will happen to these two popular concepts?Snowball Earth Melts:  The idea that prior to the emergence of complex life the Earth was frozen over has been given the colorful title, “Snowball Earth.”  Scientists at Imperial College, London, are questioning whether this ever happened, according to EurekAlert.  They claim to have found evidence of repeated hot and cold cycles that would not have allowed Earth to undergo a prolonged period of freezing.  They also questioned it on thermodynamic grounds: “In fact, once fully frozen, it is difficult to create the right conditions to cause a thaw, since much of the incoming solar radiation would be reflected back by the snow and ice.” Antarctic rivers drain Antarctic lakes:  Many scientists had speculated that lakes under Antarctic ice might hold pristine clues to the early Earth, and exotic forms of life.  Now they may have to take into account a paper in Science1 that found evidence these lakes are connected and drain from one to another as the ice cover shifts.  Images from space show that these lakes act like lubricants and rapidly shift the highly-pressurized subglacial ice around.  They cited instances: “Large outbursts of subglacial water have been observed in coastal regions,” and “Antarctic subglacial water can move in large volumes between lakes, on short time scales and over long distances.”    In conclusion, they remark that the water movements they detected are “large, extensive, and temporally variable.”  Big changes were seen within just 2-3 years.  “These observations provide clues to understanding the stability of ice streams through their sensitivity to basal lubrication,” they said.  “The time scale for subglacial water transport (months to years) is short compared with that of other known drivers of glacial flow variability, suggesting a mechanism for more rapid changes in ice stream behavior than have previously been assumed.”It may be a hard sell, therefore, to claim that anything under the Antarctic remained stable for millions of years – or that we can know with any certainty what the Earth looked like before there were observers.1Fricker, Scambos, Bindschadler and Padman, “An Active Subglacial Water System in West Antarctica Mapped from Space,” Science, 16 March 2007: Vol. 315. no. 5818, pp. 1544-1548, DOI: 10.1126/science.1136897.Didn’t they ever hear of global warming?  Indeed, the science wars are heating up all over the world.(Visited 6 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img

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