Iridium-rich layers and catastrophismKyte et al have discovered a 2.3-million year-old sedimentary layer under the Antarctic Ocean that contains iridium and gold concentrations comparable to those in the Cretaceous-Tertiary boundary. The noble metals are mostly contained in millimeter-sized grains that resemble ablation debris from a large extraterrestrial object. Unlike the Cretaceous-Tertiary episode, however, the newly found layer is not accompanied by evidence of mass biological extinctions.
William R. Corliss
No. 18: Nov-Dec 1981When Antarctica Was GreenPeter Webb and his coworkers have found pollen and the remains of roots and stems of plants in an area stretching some 1300 kilometers along the Transantarctic Mountains. The Antarctic wood is so recent that it floats and burns with ease. Webb's group postulates that a shrub-like forest grew in Antarctica as recently as 3 million years ago... Nevertheless, these deposits of fresh-looking wood do suggest that trees recently grew only 400 miles from the South Pole. Also of interest is the fact that the sedimentary layers containing the wood have been displaced as much as 3000 meters by faults, indicating recent large-scale geological changes.
William R. Corliss
No. 45: May-Jun 1986An Antarctic Bone BedW. Zinsmeister was accustomed to scoff at the idea that the Age of Dinosaurs ended violently with the impact of a giant asteroid some 65 million years ago. He always asked: "Where's the layer of burnt and twisted dinosaur bones?" His certainty was shaken, however, when he began mapping fossil deposits on Seymour Island, Antarctica. He didn't find the dinosaur bones but rather a giant bed of fish bones at least 50 square kilometers in area. Some sort of catastrophe must have annihilated untold millions of fish. And guess what? This great bone bed was deposited directly on top of that layer of extraterrestrial iridium that marks the 65-million-year-old Cretaceous Tertiary boundary at many sites around the world.
William R. Corliss
No. 104: Mar-Apr 1996
Earth in the BalanceGregory Jenkins, a meteorologist at Pennsylvania State University [writes that] 3.8 million to 2.5 billion years ago, its surface was warm enough for life even though the young sun was much fainter than it is today. Jenkins found he could explain the balmy temperatures if Earth had been rotating sideways at the time. Recently, geologists have found evidence of glaciers at Earth's equator between 800 million and 540 million years ago. When Jenkins modeled what the climate would have been like during that time if Earth's axis were tilted at a steep, 70-degree angle, ice appeared at the equator.
by Jessica Gorman
DISCOVER Vol. 21 No. 4 (April 2000)
According to the theory, Earth remained off kilter until around the beginning of the Cambrian Period, 540 million years ago, when a buildup of continents near the south pole flipped our planet to its present 23-degree tilt. The switch to a less extreme climate could explain the remarkable diversification of life at that time. "This is radically different than what most of us think about Earth," Jenkins says.Earth's Core Spins Independently Of The Rest Of The PlanetColumbia scientists Xiadong Song and Paul Richards have combined computer simulations with measurements of seismic waves traveling through the Earth to deduce the rotational behavior of the planet's deep interior. What they find is that the solid inner core---which might consist of a single immense crystal of iron 2400 km across---rotates slightly faster than the rest of the world. The tiny differential spin amounts to about one degree a year. This means that the equator of the inner core swivels past the inside of the outer core at a rate of tens of km per year, 100,000 times faster than the fastest tectonic plates move past each other up near the Earth's surface. A better understanding of how the core gimbals about would in turn provide insights into the nature of Earth's magnetic field, which has reversed itself many times over geological time. (Nature, 18 July 1996.)
by Phillip F. Schewe and Ben Stein
Physics News Update
Number 280 (Story #1), July 22, 1996