GeoBlog |
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August 29, 2001
A Radiometric Dating Resource List. Another good resource.
Radiometric dating tables. I'm giving a lecture on this today and found this to be a useful site. Good for case examples.
August 27, 2001
Also from EurekAlert: Well preserved meteorite yields clues to carbon evolution in space. "The first results are in from the organic analysis of the Tagish Lake Meteorite, a rare, carbon-rich meteorite classified as a "carbonaceous chondrite" that fell on a frozen Canadian lake in January 2000 and is the most pristine specimen ever studied of this group of important space objects.
Carbonaceous chondrite meteorites contain vital clues to the evolution of carbon compounds in our solar system preceding the origin of life. The analysis, conducted by a team headed by chemist Sandra Pizzarello, a research scientist at Arizona State University, on 4.5 grams taken from the sealed interior of the meteorite, found organic compounds in the meteorite with some similarities to other known carbonaceous chondrites, but also clear differences -- most notably the near-absence of the amino acids found in some meteorites studied before. In an article scheduled to appear in the August 24 issue of the online journal Science Express (with publication in Science to follow) the team notes that the chemistry of the Tagish Lake Meteorite appears to preserve organics that accumulated or developed in the early history of the Solar System including molecular bubbles of carbon (fullerenes or "buckyballs") containing the noble gasses helium and argon in a ratio similar to the gas and dust cloud that formed the planets -- and thus perhaps reflects an early stage in a process of evolution of complex carbon compounds in space."
From EurekAlert!: Seismic doubleheader: Seismologist shows deep earthquakes come in pairs. "Seismologists now know that deep earthquakes like to do just like baseball immortal Ernie Banks liked to : "Play two today." Douglas A. Wiens, Ph.D., professor of earth and planetary sciences at Washington University in St. Louis, has seismic wave evidence that many deep earthquakes in the Tonga area occur at the same spot repeatedly and often occur in pairs.
The second earthquake generally has the same magnitude and follows the first within one day. These earthquake doubleheaders are seldom found for earthquakes at shallow depths, such as along the San Andreas Fault. These results may imply that earthquakes deeper than 300 miles do not represent brittle slip along a fault, as do shallow earthquakes that can be studied more readily. " August 24, 2001
From UniSci: Plausible Biological Cause For Major Climate Events. "The largest genetic study ever performed to learn when land plants and fungi first appeared on the Earth has revealed a plausible biological cause for two major climate events.
Those events are the Snowball Earth eras, when ice periodically covered the globe, and the era called the Cambrian Explosion, which produced the first fossils of almost all major categories of animals living today." Sounds very interesting! August 23, 2001
From EurekaAlert: Is Earth's magnetic field failing?. "It might even be a matter of life or death. The Earth's field is one of nature's great gifts, shielding us from lethal cosmic radiation and possibly stopping our atmosphere being stripped away by the ravages of the solar wind. If our magnetic field were to switch off entirely, the Earth could become as sterile as Mars.
Our protective shield is unlikely to fail permanently, but a temporary shutdown may be imminent. It could happen within as little as 2000 years. Measurements of the Earth's field show that it is getting weaker, and suggest that we are heading for a field reversal, in which the north and south magnetic poles will swap. When the reversal is in full swing, there will be a time when the field sinks almost to zero before cranking up again. This unprotected period might only last for a few years, or it could go on for thousands. To know for sure, we'll need a very precise model of the Earth's core. " August 22, 2001
From the New York Times: Ancient Coral May Hold Hint of Worsening Weather Cycle. "Reading chemical clues etched in coral up to 130,000 years old, geologists say it appears that El Niño and La Niña, the pulses of warm and cool Pacific waters that can lead to Indonesian droughts and Idaho blizzards, have almost never before reached the sustained intensity seen in the past century." This is kind of old news, but nonetheless it is interesting.
August 17, 2001
Roman Numeral and Date Conversion with Roman Calculator & Test. I know some physicists that would really go for this.
August 16, 2001
From the Washington Post: Planetary System Found Similar to the Sun's. I hadn't posted here in a long time, so I thought this would be a good article to get things going.
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