Geonews Clips – April 28, 2008

• The argon-argon age analysis method is used to determine the age of rocks over a wide time span. However, Paul Renne, director of the Berkeley Geochronology Center and an adjunct professor of earth and planetary science at UC Berkeley, has contended that this method had systematic errors that resulted in uncertainties of about 2.5 percent in age analyses. Recent refinements to this technique have greatly improved precision in age analyses.

• The National Seismic Hazard Maps just published by the U.S. Geological Survey provides assessment of earthquake hazards estimation for the United States.

• Carbon dioxide levels were well regulated for hundreds of thousands of years by the Earth's natural feedback mechanism say scientists in the journal Nature Geoscience. They also state that human activity is now the cause for elevated CO2 emissions such that the planet's natural balancing mechanism cannot keep up.
  
  Go to www.earthmaps.com/geology_news.htm for links to these topics.

Geonews Clips – April 15, 2008

• Is the Grand Canyon millions of years old? New research on the Grand Canyon formation suggests that parts of the canyon were formed more than 50 million years earlier than previously thought. Most researchers pegged the canyon’s formation at about 6 million years ago. Age analyses of rocks based upon uranium-thorium-helium dating, however, indicate that rocks from both the rim and floor of the Upper Granite Gorge cooled at the same time – about 55 million years ago – supporting the premise that the gorge formed from pre-existing canyons.

• An intact, frozen baby woolly mammoth found in the Russian Arctic last year underwent computer tomography scans recently. The scans revealed the first in-depth internal information of an extinct mammal.

• Vanishing lake? It happened in Chile where melt water from a glacier filled a lake thereby increasing pressure on the associated ice sheet. The lake water finally emptied into a nearby river – the emptying lake water initiated a tsunami that rolled through the nearby river.

• Reduction in cloud cover boosted Cretaceous warming spell? Scientists suggest that although atmospheric levels of carbon dioxide were 4 times higher than today’s levels, it was still not enough to produce the tropical temperatures that existed during the Cretaceous. The lack of cloud cover could result in increased temperatures – and if this is correct, it has implications for today’s global warming models.

Links to these news clips are posted at: www.earthmaps.com/geology_news.htm