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... Science Frontiers ONLINE No. 53: Sep-Oct 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Meteor-impact winters, magnetic field reversals and tektites "Nuclear winter" is a term now in vogue. And, believe it or not, the rains of tektites discussed below may have been the forerunners of climatic catastrophes similar to the postulated nuclear winters. We shall call them "meteor-impact winters. First, a tad of background: Great meteor impacts and tektite ... not immediate according to both calculations and analyses of sediments. After the impact event, the dipole field decreases for a few thousand years, followed by a longer hiatus. Then, there is a sudden reversal. (Schwartzschild, Bertram; "Do Asteroid Impacts Trigger Geomagnetic Reversals?" Physics Today, 40:17, February 1987.) Comment. In trying to relate all this to our present situation, recall that a major "ice age" is just a few millenia behind us, and our dipole field has been ... slowly for as long as we have been able to measure it. Brace yourselves! Reference. There are many anomalies associated with the tektites. See ESM3 in our catalog: Neglected Geological Anomalies. Ordering information here . From Science Frontiers #53, SEP-OCT 1987 . 1987-2000 William R. Corliss ...
Terms matched: 4 - Score: 1799 - 15 May 2017 - URL: /sf053/sf053g11.htm
... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Geomagnetic Reversals From Impacts On The Earth R.A . Muller and D.E . Morris review the evidence tying geomagnetic reversals to the impacts of large bodies with the earth: the tektites and microtektites; the climate changes; the biological extinctions, etc. Then they propose a physical mechanism for geomagnetic reversals: "The impact of a large extraterrestrial object on the Earth can ... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Geomagnetic Reversals From Impacts On The Earth R.A . Muller and D.E . Morris review the evidence tying geomagnetic reversals to the impacts of large bodies with the earth: the tektites and microtektites; the climate changes; the biological extinctions, etc. Then they propose a physical mechanism for geomagnetic reversals: "The impact of a large extraterrestrial object on the Earth can ... sea-level change is sufficiently large ( 10 meters) and rapid (in a few hundred years), then the velocity shear in the liquid core disrupts the convective cells that drive the dynamo. The new convective cells that subsequently form distort and tangle the previous field, reducing the dipole component near to zero while increasing the energy in multipole components. Eventually a dipole is rebuilt by dynamo action, and the event is seen either as a geomagnetic reversal or as an excursion." (Muller, Richard A., and ...
Terms matched: 4 - Score: 1624 - 15 May 2017 - URL: /sf049/sf049p18.htm
... the inner core. In concept, the heat lost at the core-mantle boundary might be linked to climate changes and sea-floor spreading. Taking a different tack, D. Gubbins has investigated the possibility that field reversals are triggered by ice ages and meteorite impacts (tektite falls). The physical mechanism here would be the increase in pressure upon the core, which affects the rate of freezing in the outer core, and thus the power available to the core dynamo. Gubbins found that these externally caused pressure changes were ... , global ice volumes, sea-floor spreading rates, and deposition of black shales, tektite falls, biological extinctions, etc. The frustrating thing is the lack of clear-cut cause and effect; that is, how these phenomena are linked physically to the geomagnetic field. Part of the problem is that we can only guess at how the geomagnetic field is generated. Let us assume that the earth's magnetic field is created by dynamo action in the planet's fluid core. P. Olson finds analytically that ... Science Frontiers ONLINE No. 34: Jul-Aug 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Behind magnetic flip-flops The earth's magnetic field frequently reverses its polarity. Such flips can of-ten be correlated with climate changes, global ice volumes, sea-floor spreading rates, and deposition of black shales, tektite falls, biological extinctions, etc. The frustrating thing is the lack of clear-cut cause and effect; that is, how these ...
Terms matched: 4 - Score: 1522 - 15 May 2017 - URL: /sf034/sf034p15.htm
