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... Science Frontiers ONLINE No. 80: Mar-Apr 1992 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Steens Mountain Conundrum The layered lava flows of Steens Mountain, in southeastern Oregon, have preserved video-like records of the earth's magnetic field as it switched from one polarity to another about 15.5 million years ago. The scientific "instruments" here are the cooling lava flows. As they solidify from the outside in, a process taking about 2 weeks for a 2meter-thick flow, the lava is magnetized in the direction of the field prevailing at the moment of solidification. We would thus have a 2-week continuous record of the behavior of the earth's field. Ordinarily, we would not expect ... see very much change in 2 weeks; even a reversing field is thought to take thousands of years to complete its flip-flop. However, at Steens Mountain, when the field reversed 15.5 million years ago, the lava flows suggest that the field's axis was rotating 3-8 per day -- incredibly fast according to current thinking, in fact a thousand times faster than expected. The conundrum (one might call it a scientific impasse) arises because the flowing electrically conducting fluids that supposedly constitute the earth's dynamo would have to flow at speeds of several kilometers/hour. No one has ever contemplated molten rock moving at such speeds in the core! (Appenzeller, Tim; "A Conundrum at Steens Mountain," Science, 255:31, ...
Terms matched: 2 - Score: 542 - 15 May 2017 - URL: /sf080/sf080g13.htm
... Science Frontiers ONLINE No. 101: Sep-Oct 1995 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects "ALMOST INCONCEIVABLE" CHANGES IN THE GEOMAGNETIC FIELD A decade ago, a trio of geophysicists published a group of papers based on their measurements of the remnant magnetism of the 16-million-year-old layered lava flows at Steens Mountain, Oregon. (SF#45) At that time, they claimed that these finely bedded lava flows testified that, during a field reversal, the earth's field swung around at the astonishing rate of 3 per day! This rate is about one thousand times the current rate of polar drift. Mainstream geophysicists could not believe the 3 /day figure because it implied incredibly rapid changes in the ... of those molten materials within the earth that supposedly generate the geomagnetic field. The Steens Mountain data were "tabled"; that is, dismissed. The three researchers, though, continued their labors at Steens Mountain and have now offered additional, even more impressive data. They now find that the geomagnetic field probably shifted as much as 6 in a single day. Their work has been carried forward so professionally and meticulously that other scientists are finding their conclusions harder and harder to dismiss. Instead, the search is on for explanations of the rapid field changes. Three possibilities have been advanced -- all of them unpalatable to geophysicists: The Steens Mountain rocks are not faithful recorders of the main geomagnetic field. Should this be actually so, the whole field of paleomagnetism, including plate tectonics, ...
Terms matched: 2 - Score: 271 - 15 May 2017 - URL: /sf101/sf101g11.htm
... field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals." The time period required for the field to reverse was about 4500 years, as measured at Steens Mountain, Oregon. There were three periods of very rapid change (impulses), which hint at radical changes in the core. The average magnetic field at the earth's surface decreased to 20% of normal during the reversal. (Prevot, Michel, et al; "How the Geomagnetic Field Vector Reverses Polarity," Nature, 316:230, 1985.) Comment. ... illustration reveals that the reversal was far from a clean 180 flip; there was much meandering. Just what was happening in the core during the reversal is a mystery. When the magnetic field dropped to low levels, flux of cosmic rays and other radiation at the earth's surface probably increased drastically. Terrestrial life might have been adversely affected. The Steene Mountains directional record. The numbers refer to the samples used from the volcanic sequence, in order of increasing age. Dotted lines represent field directions in the opposite hemisphere. From Science Frontiers #41, SEP-OCT 1985 . 1985-2000 William R. Corliss ...
Terms matched: 2 - Score: 222 - 15 May 2017 - URL: /sf041/sf041p13.htm
... Archaeology Ancient greek pyramids? The great wooden well of kuckhoven Astronomy What fluid cut the styx? More evidence for galactic "shells" or "something else" The nullarbor lode Biology Cricket coordination Thousands of grebes fall from the skies Spider swordplay Archaea: the living ancestors of all life forms Life-creation from a different perspective Geology Possible chain of meteorite scars in argentina Dinosaur flatulence and climate changes The steens mountain conundrum Aerial bioluminescence Dead water Concentric, rotating luminous rings seen in sweden Anomalous optical events in the upper atmosphere Unidentified light Unclassified First cold-fusion bomb? When the chips are down ...
Terms matched: 2 - Score: 183 - 15 May 2017 - URL: /sf080/index.htm
