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The rise of the Appalachian Mountains may have caused a major ice age approximately 450 million years ago, an Ohio State University study has found. The weathering of the mountains pulled carbon dioxide (CO2) from the atmosphere, causing the opposite of a greenhouse effect -- an "icehouse" effect. Scientists have suspected that our current ice age, which began 40 million years ago, was caused by the rise of the Himalayas. This new study links a much earlier major ice age --one that occurred during the Ordovician period -- to the uplift of the early Appalachians . It also reinforces the...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 August 28 3D Mars: Northern Terra Meridiani Credit: Malin Space Science Systems, MGS, JPL, NASA Explanation: In this spectacular 3D stereoscopic view from orbit, steep-sided, flat-topped hills stand above the Terra Meridiani region of Mars. Seen best with red/blue glasses (red for the left eye), the structures are reminiscent of buttes and mesas found in southwestern areas of the North American continent on planet Earth. Like their...