... . First, a tad of background: Great meteor impacts and tektite events seem to have occurred nearly simultaneously with deep-cutting biological extinctions and reversals of the earth's magnetic field. Ever since this apparent synchrony was recognized a few decades ago, theorists have been vying in generating scientific scenarios, especially some mechanism that would reverse the earth's magnetic field. New entrants in the lists are R. Muller and D. Morris, two Berkeley physicists. Here is how they see it: "A sufficiently large asteroid or cometary nucleus hitting the Earth lofts enough dust to set off something like a 'nuclear winter.' The cold persists long after the dust settles because of the increased reflectivity of the snow-covered continents. In the course of a few centuries, enough equatorial ocean water is transported to the polar ice caps to drop the sea level about 10 meters and thus reduce the moment of inertia of the solid outer reaches of the Earth (crust and mantle) by a part in a million. 'That doesn't sound like much, Morris told us. 'But when we realized that this translates into a full radian of slippage between mantle and core in just 500 years, we began to look seriously at the consequences.' With the moment of inertia of the crust and mantle 'suddenly' decreased, the argument goes, they begin spinning faster than the solid-iron inner core at the center of the Earth. The 2300-km thick shell of liquid outer core that separates the mantle from the inner core thus acquires a velocity shear ...

... .00pm, a total of five jets passed overhead, all leaving vapour trails. Two showed a very interesting phenomenon, because while the vapour trails extended eastwards, the trails were continued westwards in front of the planes as dark lines which stretched all the way to the horizon. It was as if the plane was running on an aerial railway. I think it significant that only two of the planes showed this phenomenon as I suspect it was heightdependent. At this time the sun was high and shining from the south-southwest." J.O . Mattsson, Lund University, surmised that the black streaks in front of aircraft were shadows of the condensation trails behind the two planes. The shadows were cast forward ahead of the planes upon the hazy, though cloudless, atmosphere above the ocean. (Evans, Alun; "Condensation Trail Shadows," Weather, 53:371, 1998.) Comment. Since the sun was high in the sky, it is difficult to visualize how a the vapor-trail shadow could be cast directly ahead of the aircraft. Hummm! We suppose that the vapor trails acted like those sunset clouds that produce crepuscular rays. The geometry, though, is a bit different. Digitized sketch of contrail phenomenon. Apparently, the contrail's shadow was projected on the misty atmosphere ahead of the aircraft. From Science Frontiers #123, MAY-JUN 1999 . 1999-2000 William R. Corliss ...

... 1996 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Fossil Mantle Plume Under South America "In a challenge to a major aspect of the theory of plate tectonics, NSF-supported scientists have discovered the presence of an ancient conduit deep in the Earth's mantle beneath Brazil. "The conduit appears to have remained geographically fixed with respect to the overlying continent despite thousands of kilometers of South American plate motion. This observation runs contrary to a major tenet of plate tectonic theory -- that the motion of lithospheric plates is essentially independent of flow in the upper mantle beneath the plates -- and implies that the upper mantle and the overlying South American continent have remained coupled since the breakup of the Gondwanaland super-continent and opening of the South Atlantic Ocean some 120 million years ago. This result also implies that large-scale convection in the mantle may be responsible for the motion of the great continental plates, such as South America, where the driving force for plate motion has not been well understood." (Dybas, Cheryl; NSFNEWS Digest 54, November 8, 1995. Cr. D. Swaner. NSF= National Science Foundation. The cyber-address for the NSFNEWS Digest is: [email protected] The computerless may read more in: VanDecar, John C., et al; "Seismic Evidence for a Fossil Mantle Plume beneath South America and Implications for Plate Driving Forces," Nature, 378:25, 1995. From Science Frontiers #103, JAN-FEB 1996 . 1996-2000 William R ...

... Science Frontiers ONLINE No. 14: Winter 1981 Supplement Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Worms with inside-out stomachs The recently discovered tube worms, living near the hot water vents on the ocean bottom off the Galapagos, have no mouths or guts. Their bodies are covered with thousands of feathery tentacles, each packed with blood vessels. Apparently, the tube worms extract nutrients directly from the sea water and expel wastes the same way -- having in effect external stomachs. These worms, which may be many feet long, contain enzymes that permit them to extract carbon dioxide from the seawater and fix it much like plants do during photosynthesis. George Somero, at Scripps, estimates that the enzyme levels in the worms are similar to those in a spinach leaf. (Anonymous; "15-Foot Sea Worm Has Plant Qualities," San Diego Evening Tribune, May 22, 1980. UPI dispatch) Comment. This curious biological anomaly developed in an ecological niche where the primary energy source for sustaining life is geothermal rather than solar. How did this remarkable situation arise? Do the tube worms have relatives in the fossil record showing a step-by-step development of inside-out stomachs? From Science Frontiers #14, Winter 1981 . 1981-2000 William R. Corliss ...

... of coral, scientists hope to spot natural and man-made changes in global chemistry. For example, the large-scale use of fossil fuels should depress the ratio by adding carbon-12 in undue quanti ties. The advent of the nuclear age boosts the ratio through the addition of carbon-14 to the environment. Predictably, the carbon ratio rises dramatical ly after 1950 (the bomb tests, etc.). Before this date, however, anomalies crop up: Coral-ring and tree-ring data differ substantaially when they should not; Coral-ring carbon ratios from relatively close locales, such as Bermuda (solid line) and the Florida Keys (dashed line), also differ significantly. Item 1 might be due to non-atmospheric carbon upwelling in deep-ocean water; but this would not explain the Bermuda and Florida discrepancies. (Anonymous; "Carbon-14 Variations in Coral," Open Earth, No. 3 p. 30, 1979 Comment. These discrepancies are particularly relevant to the carbon-14 dating of seashells, which often produces wildly incorrect ages. From Science Frontiers #8 , Fall 1979 . 1979-2000 William R. Corliss ...

... . Since Antarctica is often buffeted by fierce winds, one would naturally think that these snow dunes have an aeolian origin like desert sand dunes. This does not seem the be the case. Comparisons made using recently declassified images taken in the 1960s by U.S . military satellites reveal that the snow dunes have not moved in over 30 years! Some-thing besides wind-driven snow must be helping to sculpt these immense stationary patterns. (Tomlin, Sarah; "Vast Snow Dunes Frozen in Time," Nature, 402:860, 1999.) Comment. The fossil "string dunes" of Australia closely resemble the Antarctic snow megadunes in pattern and size, but of course they are composed of sand. "Megaripples" charted by sonar and shaped by water currents on the ocean floors are also comparable. See ETR3 in Carolina Bays for more. From Science Frontiers #128, MAR-APR 2000 . 1997 William R. Corliss Other Sites of Interest SIS . Catastrophism, archaeoastronomy, ancient history, mythology and astronomy. Lobster . The journal of intelligence and political conspiracy (CIA, FBI, JFK, MI5, NSA, etc) Homeworking.com . Free resource for people thinking about working at home. ABC dating and personals . For people looking for relationships. Place your ad free. ...

... the supposedly pristine air of Alaska is defiled by a peculiar haze concentrated at about 10,000 feet. The sky has a whitish, diffuse look; from an airplane the horizon seems to disappear entirely. Is the haze due to pollutants in this remote region? Recent studies indicate two components in the haze: (1 ) Dust, and (2 ) Sulfuric acid droplets. Both of these must be imported because there are no sources of such materials in the arctic. Violent wind storms in the Gobi Desert may carry some dust into the arctic. Strong winds might also transport sulphuric acid from Japanese industries to Alaska. These are speculations, though, and no one is sure where this haze comes from or how far it extends beyond Alaska into the stable, stagnant air over the Arctic Ocean. (Anonymous; "Alaska's Imported Haze," Mozaic, 9:41, September/October 1978.) From Science Frontiers #6 , February 1979 . 1979-2000 William R. Corliss ...

... be forced if just a small portion of the gases frozen under the sea floor were released into the atmosphere. Gas-hydrates are unimpressive when brought to the surface -- just dirty, fizzy ice. However, taken together, they contain more carbon than all the world's oil fields, perhaps much more. Most estimates fall between 1,700 and 11,000 billion tons, but there is one scientist who pegs these cold-storage carbon deposits at 4,100,000 billion tons. In comparison, human releases of carbon to the atmosphere via the burning of wood, gas, coal, and even the collective flatulence of all the planet's animals are trivial. Geological evidence confirms that past climate swings were associated with large injections of carbon into the atmosphere and oceans. A major contributor to these "carbon burps" may be decomposing methane hydrate. Until recently, climatologists have questioned the sizes of gas-hydrate deposits, but cores extracted from the Blake Ridge off the Carolina coast confirm the immense amounts of gases precariously locked up in sea-floor sediments. The stratum of gas hydrates in the Blake Ridge alone covers 26,000 square kilometers -- enough gas is there to supply the U.S . for 107 years. In biological terms the Blake Ridge's carbon is equal to 7% of the carbon locked up in all terrestrial biota -- animals, trees, grasses, etc. And the Blake Ridge gas hydrates represent a miniscule fraction of the planet's frozen gas hydrates. (Dickens, Gerald R., et ...

... 151:279, 1997.) Once we learn how to measure neutrinos really well, we can start looking for intelligent signals impressed upon them by advanced extraterrestrial civilizations. W. Simmons and colleagues at the University of Hawaii at Manoa point out that neutrinos are much better than electromagnetic waves for galaxy-wide communication. They are not blocked by dust nor are they smeared out by ionized gas. Any civilization clever enough to colonize the entire galaxy would want to send out neutrino signals if only to keep clocks in far-flung star systems synchronized. Simmons et al calculate that a neutrino detector containing a cubic kilometer of seawater could probably detect neutrino signals from artificial sources located within 3,000 light years of earth. A detector that might be able to do this is being installed in the ocean off the Hawaiian Islands. Naturally, it has an acronym: DUMAND = Deep Underwater Muon and Neutrino Detector. (Chown, Marcus; "Do ETs Phone Home with Neutrinos?" New Scientist, p. 19, December 3, 1994.) Reference. The problem of the missing solar neutrinos is discussed at length in Section ASF3 in our Catalog The Sun and Solar System Debris. For ordering information, visit here . From Science Frontiers #112, JUL-AUG 1997 . 1997-2000 William R. Corliss ...

... Project Sourcebook Subjects A Sinuous Line Of Sea Snakes In the Malacca Straits, on May 4, 1932, a surface congregation of sea snakes 10 feet wide and 60 miles long was observed. Helicopter pilots off Viet Nam and Pakistan have reported similar but much smaller concentrations. Groups of several thousand have also been noted in Panama Bay. This tendency to gather in great numbers at the surface is an enigmatic aspect of sea snakes. One possible answer may lie in the surface feeding habits of some species, such as the yellow-bellied sea snake. These creatures seem to float passively on the sea surface, feeding and reproducing, letting the winds and currents accumulate them in long drift lines. (Minton, Sherman A., and Heatwole, Harold; "Snakes and the Sea," Oceans, 11:53, April 1978.) From Science Frontiers #4 , July 1978 . 1978-2000 William R. Corliss ...

... Science Frontiers ONLINE No. 133: JAN-FEB 2001 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Ribbons In The Sky November 18, 1999. North Atlantic Ocean. Aboard the m.v . Waterford enroute from Pto Bolivar, Columbia, to Ijmuiden. At 1832 UTC an azimuth of Jupiter was taken shortly after sunset. The sky in the vicinity of Jupiter was completely clear, no cloud of any type, with but a few small cumulus dotted around the horizon. About five minutes later, having completed the calculations, the observer again looked out to see a ribbon type cloud, broken in formation, stretching almost from [the] eastern horizon to [the] western horizon. If the estimated height (see below) is reasonably correct, then the bandwidth couldn't have been more than a few hundred feet, apparently more cigar-shaped in cross section than flat, the maximum axis being horizontal, the minimum vertical. The cloud was fairly consistent in density, and at a fairly stable altitude, not undulating or rippled, having the consistency of a small cumulus cloud (white and fleecy), but also translucent. Initially, it was thought to be a condensation trail, but this was shortly dismissed as it was considered too low (estimated to be less than 10,000 ft altitude, probably around 7,0008,000 ft). Both ends of the cloud were checked with binoculars but no aircraft was evident; however, as a yardstick, and by good fortune, one did appear ...

... been correlated with biological extinctions, magnetic field reversals, and basalt flooding. The astronomical causes of this supposed periodicity range from the solar-system's crossing of the galactic plane, to the perturbations of an unseen solar companion, to regular perturbations of the Oort cloud of comets that is thought to hover at the fringe of the solar system. In short, a large, interlocking edifice of geological and astronomical speculation has been erected upon a foundation of terrestrial crater ages. But how well do we really know the ages of these craters? How complete is the cratering record? The answer to the first question is: "Not well at all." Further, we can be certain that many craters still lie undiscovered beneath sediments. In addition, most meteors/comets splashed into the oceans, leaving no record at all. An updating of the most recent crater data available, such as they are, greatly weakens the case for the popular 28-31 million-year period and strengthens support for a 19-22 million-year period. But neither cycle is in synchronism with the famous K-T (Cretaceous-Tertiary) Boundary, with its perplexing iridium layer and massive biological extinctions. In fact, say V.L . Sharpton et al, the entire known cratering record could well be the consequence of chance encounters between the earth and stray meteors and comets. Thus would pass the periodicities of this world! (Sharpton, V.L . et al; "Periodicity in the Earth's Cratering Record?" Eos, 68: 344, 1987 ...

... . Weak though it may be, gravity controls the trajectory of a baseball, the motion of the planets, and the shape of our Galaxy. Physicists describe gravitation with Newton's Law of Gravitation, which incorporates the Gravitational Constant G. Here's where the embarrassment arises. Many other constants of nature, such as the charge on the electron, are known to eight significant figures. We only know G to three. What's worse, modern attempts to refine the measurement of G come up with wildly different answers. Torsion-pendulum experiments in the U.S ., Germany, and New Zealand are far apart in their G-measurements. And physicists are perplexed -- to put it mildly. Of course, G is hard to measure. Seismic waves from ocean surf hundreds of miles away can affect the experiments. If a colleague a few offices away brings in some boxes of books for his library, the experiment is compromised. Better instrument science may eventually resolve the too-large discrepancies between the measured values of G, but some physicists worry that perhaps the problem runs deeper. "If experiments find that G is changing slowly over time, for example, physicists would have to rethink how space and time are stitched together in a single fabric. Einstein would groan in his grave." (Kestenbaum, David; "The Legend of Big G," New Scientist, p. 39, January 17, 1998.) From Science Frontiers #116, MAR-APR 1998 . 1998-2000 William R. Corliss ...

... .R . Hawke, of the University of Hawaii, have acquired near-infrared spectra of the swirl designated Reiner Gamma. They report that the composition of the swirl material does not match the crater ejecta; and, also, that a previously undetected reddish halo surrounds the swirl. Best guess at present: The swirls are the scars of comets -- probably less than 100 million years old. (Anonymous; "Cometary Scars on the Moon," Sky and Telescope, 75:11, 1988.) Comment. Does nearby earth also bear cometary scars? Some think that the 1908 Tunguska Event was a cometary impact. (See ETC2 in our catalog: Caro lina Bays, Mima Mounds .) Also see the the item below under GEOLOGY about comets and the earth's oceans. Reference. Both catalog volumes mentioned above are described here . From Science Frontiers #56, MAR-APR 1988 . 1988-2000 William R. Corliss ...

... a major snowstorm or flooding rains would hit northeastern states within six days. Wollin contacted the weather people in the region, but they discounted the prediction because satellite pictures and conventional weather indicators implied nothing of the sort. A three-day storm began on January 25, depositing 3 feet of snow in northern New England and 4 inches of rain along the coast from Washington to Boston. Wollin has had similar successes, without even looking at a weather map! Obviously, Wollin's forecasting techniques are not yet part of the Weather Bureau's arsenal. This is not too surprising because even Wollin does not understand why major storms should be preceded by several days by nervous magnetometers. He talks in a tentative way about solar storms, which do affect terrestrial magnetism, dumping energy into the oceans and thence into the atmosphere. But this is mainly speculation. Historically, we do know that long-term changes in the earth's magnetic field are linked to global temperature levels (see graphs); but here, too, cause and effect are not obvious. (Gribbin, John; "Magnetic Pointers to Stormy Weather," New Scientist, p. 70, December 25, 1986.) Long-term changes in global temperature follow changes in geomagnetic intensity. From Science Frontiers #50, MAR-APR 1987 . 1987-2000 William R. Corliss ...

... caught in dead water, Nansen reported, Fram appeared to be held back, as if by some mysterious force, and she did not always answer the helm. In calm weather, with a light cargo, Fram was capable of 6 to 7 knots. When in dead water she was unable to make 1.5 knots. 'We made loops in our course', Nansen wrote, 'turned sometimes right around, tried all sorts of antics to get clear of it, but to very little purpose.'" Nansen asked the noted physicist and meteorologist V. Bjerknes to look into the frustrating phenomenon. Bjerknes found that the energy of the ship's propeller was, in essence, being siphoned off to create internal waves along the interface between the light fresh water and dense ocean water underneath rather than propelling the ship forward. (Walker, J.M .; "Farthest North, Dead Water and the Ekman Spiral," Weather, 46:158, 1991.) Reference. Dead water and "slippery seas" are cataloged in GHC5 in: Earthquakes, Tides. This book is described here . From Science Frontiers #80, MAR-APR 1992 . 1992-2000 William R. Corliss ...

... emerging from the thermal vents, 2200 meters below the surface...'The source of the light is still unclear,' said Joe Cann, a geologist from the University of Newcastle in Britain. The scientists suspect that the water itself is glowing." The water temperature is so high -- 350 C -- that bioluminescence is unlikely. The presence of the glow does, however, imply that photosynthesis is still possible in these sunless depths. Life forms do congregate around these vents. A curious shrimp found in the area where the glow was noted is eyeless but does possess photoreceptors on its back! (Dayton, Sylvia; "The Underwater Light Fantastic," New Scientist, p. 32, August 25, 1988. Also: Anonymous; "Mystery Glow Emanates from Ocean Bottom," Albuquerque Tribune, August 18, 1988. Cr. D. Eccles.) From Science Frontiers #60, NOV-DEC 1988 . 1988-2000 William R. Corliss ...

... custom-arily explain drumlins as debris piled up and sculpted by the ice sheets them-selves, despite the fact they look like they might have been shaped by flowing water. As we all know, the word "flood" is an anathema in geology, probably because a provable episode of extensive flooding would lend credence to the Biblical Flood! (Actually, many cultures around the world have similar flood legends.) Canadian geologist J. Shaw is now trying to break out of this philosophical prison. "According to Shaw, heat from the Earth formed huge lakes of meltwater that remained trapped beneath the North American ice sheet. As the sheet began to retreat near the end of the glacial age, the water broke through and flowed in torrents down to the Gulf of Mexico and Atlantic Ocean. While flowing under the ice cap, water would have surged in vast, turbulent sheets that sculpted and scoured drumlins. Each flood lasted until the weight of the ice cap once again shut off the outlet of the covered lake, Shaw says." Shaw goes on to estimate that one large drumlin field in Saskatchewan was created when 84,000 cubic kilometers of water was discharged. Just this single episode would have raised global sealevels by about 10 inches in a few days or weeks. Imagine what happened as this water flowed across North America. Many geologists look askance at Shaw's theory of drumlin formation. (Monastersky, R.; "Hills Point to Catastrophic Ice Age Floods," Science News, 136:213, 1989.) Comment. The famous Channelled Scablands ...

... there and when? (2 ) Hydrothermal-vent communities have been discovered at a depth of about 400 meters in the northern part of the lake. These communities contain sponges, bacterial mats, snails, transparent shrimp, and fish; some of which are new to science. Baikal's thermal vents are the only ones known in freshwater lakes. Their rela tion to saltwater vent communities has not yet been explored. (Stewart, John Massey; "Baikal's Hidden Depths," New Scientist, p. 42, June 23, 1990. Also: Monastersky, R.; "Life Blooms on Floor of Deep Siberian Lake," Science News, 138:103, 1990.) Comment. Despite its inland position, the suspicion develops that Baikal was connected to the oceans in recent geological times. From Science Frontiers #72, NOV-DEC 1990 . 1990-2000 William R. Corliss ...

... shallow seas. Whether this outgassing of methane comes from shallow accumulations of organic matter or from deep within the crust is still debated. Here, geophysics merges with biology. Recently, a group of researchers discovered a large (540 square meters) patch of chemosynthetic mussels in a brine-filled pockmark, at a depth of 650 meters, off the Louisiana coast. The mussels grew in a ring around the concentrated brine. The mussels harbor symbionts which consume the methane still seeping up through the brine from a salt diapir (a massive fingerlike intrusion 500 meters below the brine pool. The origin of some diapirs is not well-understood.) The mussels get the oxygen they require from the ordinary seawater covering the dense brine. Like the biological communities surrounding the "black smokers" and other ocean-floor seeps, the brine-filled pockmark community includes several species of shrimp, crabs, and tube worms. We have here another example of the astounding ability of lifeforms to take advantage of unusual, even bizarre niches. (MacDonald, I. Rosman, et al; "Chemosynthetic Mussels at a BrineFilled Pockmark in the Northern Gulf of Mexico," Science, 248:1096, 1990.) Comment. Such examples of life's adaptability are so common one hesitates to label them as anomalous. Yet, one wonders how and why life acquired this property. Is the human urge to go to the planets a genetically derived extension of this urge to colonize new terri tories. From Science Frontiers #73, JAN-FEB 1991 . 1991-2000 William R. Corliss ...

... could not call itself a science if it permitted ideas like continental drift to run rampant. Of course, the situation has now been reversed as some scientists plead that data contradicting plate tectonics should no longer be accepted for publication! Happily, at least one publication is still open to heretics. In a 1997 number of New Concepts in Global Tectonics , we find S. Keshav, at Bombay's Indian Institute of Technology, asserting that plate tectonics is a "myth that has paralyzed our thinking." And he gives some reasons for his view: Plate tectonics incorporates many physically impossible processes, such as sediment subduction; i.e ., soft sediments should be scraped off plates as they dive beneath the continents. Plate tectonics does not completely explain the ophiolites (rocks resembling bits of ocean crust that are sometimes found in embarrassing places (far inland). Plate tectonics has difficulty accounting for some mountain belts; i.e ., those far from collisional sites, like Tibet's Kunlun mountains. Finally, Keshav observes: "On the continents this theory assumes mysterious character as many of the features go unexplained (as exemplified by inability to find a trace of the Asthenosphere/Moho) and truly depicts an act of escapism." (Keshav, Shantanu; "A Myth Called Plate Tectonics," New Concepts in Global Tectonics , p. 23, no. 3, June 1997.) Comment. Keshav's objections may be a bit technical, but they reveal cracks in the foundation of a major paradigm. From Science Frontiers #125, SEP- ...

... sky either, which although virtually cloudless was very dark, and certainly darker than the atmosphere at the level of the ship. The only conclusion that the observers could come to was that this was a faint example of (to quote The Marine Observer's Handbook ), 'luminescence in the air a few feet above the sea surface when there is no light in the water'. This form lasted for about 30 minutes, whereas the bright flashes continued for three or four hours before they too eventually ceased." (Thompson, P.C .; "Bioluminescence," Marine Observer, 62:14, 1992.) Comment. Many cases of aerial marine light displays have been cataloged. It is assumed by scientists that bioluminescent particles are somehow carried into the air from the ocean, but there is no evidence at all for this. It is quite possible that some marine phosphorescent displays are electrical rather than biological. Additional examples and discussion of possible aerial phosphores-cent displays available in GLW3 in our catalog: Lightning, Auroras. To order, visit: here . From Science Frontiers #80, MAR-APR 1992 . 1992-2000 William R. Corliss ...

... Science Frontiers ONLINE No. 128: MAR-APR 2000 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Ganymede Magnetic Paradox In December 1995, the Galileo space-craft was injected into orbit around Jupiter, thereby becoming the first known artificial satellite of this giant planet. In the five years that have transpired, Galileo has radioed back voluminous data about Jupiter itself and its four large Calilean satellites. These natural satellites have turned out to be a disparate bunch. Three have iron cores, but Callisto breaks the mold with an unusual core of mixed ice and rock. Europa probably possesses an ocean, and Callisto might also. Only one of Jupiter's large satellites, Ganymede, boasts a magnetic field. In fact, Ganymede is apparently the only satellite in the solar system to display an intrinsic, dipole magnetic field like the earth's . Although Ganymere's magnetic field is like that produced by a permanent bar magnet, its core is much too hot for permanent magnetism. Again like the earth, Ganymede's field is theorized to be generated by the convection of electrically conducting liquid in its core -- a dynamo of sorts. All well and good, but Ganymede is so small that it should have cooled off billions of years ago thereby freezing its metallic core. So then, whence its magnetic field? One way out of this box it to suppose that about a billion years ago Ganymede was circling Jupiter in an orbit that took it much closer to this ponderous planet. Then, Jupiter's powerful ...

... W. Sager and A. Koppers, have plotted 27 ancient pole positions dated between 120 and 30 million years ago. Using rock samples brought up from submerged Pacific sea-mounts, they find that the earth's magnetic poles shifted 15-20-deg about 84 million years ago. The north magnetic pole was not slowly drifting, it was lurching. It took just a couple million years to shift 700 miles or more; that's more than ten times the rate of continental drift. The earth from afar must have seemed to be a disturbed top---on a geological time scale, of course! What could have perturbed the earth? One suggestion blames a sudden shifting of the planet's mass distribution, some sort of subterranean indigestion, like a subducted ocean plate suddenly plunging through into the lower mantle. (Kerr, Richard A.; "Did the Dinosaurs Live on a Topsy-Turvy Earth?" Science, 287:406, 2000.) The biological consequences of such a sudden tilting could have been severe. The event -- known as rapid true polar wander -- may have been accompanied by worldwide volcanic upheavals and reorganization of tectonic plates that would have played havoc with anything living in the Late Cretaceous period, 65 million to 99 million years ago. Although the notion that an asteroid was the immediate cause of dinosaur extinction about 65 million years ago has won wide acceptance, many paleontologists have argued that volcanic activity may have played a role in changing the climate and sending populations of the giant creatures into decline. (Bowman ...

... almost immediately while the fluid containing the parent atoms passes on. R.V . Gentry objects that mica is almost im permeable and that we must consider the possibility that our concepts of geological time are grotesquely wrong. York energetically defends established Geology using radioactive dating and paleontological arguments. His contempt of Gentry's position is scarcely veiled. This paper is an excellent review of the piechroic halo problem as well as a classic defense of the scientific status quo. (York, Derek; "Polonium Halos and Geochronology," EOS, 60:617, 1979.) Comment. York does not mention Gentry's years of careful work that led him to his heresy, nor are the many objections to radioactive dating discussed. It reminds one of the confident assertions of the permanency of the ocean basins made only a few years ago. York might be correct, but the "we now know that" approach is disturbing. From Science Frontiers #9 , Winter 1979 . 1979-2000 William R. Corliss ...