Earth Sciences134
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Building the Best Story You Can
Reconstructing a shoreline history takes skill. Today we’re using altimeters to establish the elevation of Lago Cardiel’s former shorelines. We also continue to look for shells to help us date the lake’s past shorelines, a task that requires strong powers of observation. In one short stretch there might be a dime-sized snail shell almost indistinguishable…
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Searching for Snails
Today we’re looking for live snails so that we can measure how much carbon-14 they are incorporating into their calcite shells. Carbon-14 is a rare isotope of carbon that decays radioactively–organisms incorporate carbon-14 into their tissues and shells while they are alive, and as soon as they die, the carbon-14 starts decaying away. We can…
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Looking at Mud to Learn About Ice Sheets
The bottom of the seafloor shows us where ice used to flow. To pinpoint when the ice retreated, the geologists on board take samples of mud and sand from the seafloor. Using a weighted steel barrel lowered to the seafloor they bore their way through sand and mud. A catcher at the bottom of the…
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Risks and Rewards: funding a technical earthquake response
A rapid technical response to the damaging earthquakes in Malawi produces both humanitarian and scientific benefits, and we hoped that both scientific and international assistance agencies would support our effort. Our seismic field effort serves two purposes: (1) to provide badly needed seismic equipment and technical training to the Malawi Geological Survey department (MGSD); and…
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When Lago Cardiel Was Larger
The lake has grown and shrunk many times over the past 20,000 years. When it grows, it leaves behind a “bathtub ring” of residue around its edge: pebbles smoothed by wave action, carbonate tufas, the remnants of the things that lived at the shore. There are at least three distinct bathtub rings (each of which…
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Geology Marches Forward
For most of our drive, I stare out the window and ask Mike questions: “Is that a glacial moraine?” and “How tall were the Andes originally?” and “Why are those sediments white?” He can respond to a stunning number of these questions. I love being around field geologists; the way they make sense out of…
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More Dust, Lago Potrok Aike
Jay and Barbara took off this morning in a rugged-looking truck while Mike and I followed in a Honda CR-V that looks more appropriate for Route 9W than Patagonia’s gravel roads. We’re hopeful that nothing terrible will go wrong. Wish us luck! I was totally entranced by the geomorphology of this place: I must have…
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Some Thoughts About Dust, Rio Gallegos
I’ve been to Stewart Island, off the southern tip of New Zealand, but I’m pretty sure this is the furthest south I’ve been. Cool! We’re here in Rio Gallegos. We’ve just rendezvoused with Dr. Jay Quade, a geologist from the University of Arizona, and his wife Barbara. We’ve got two cars, a bunch of boxes…
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Assessing Continuing Quake Risks, by Sea
This week U.S. and Haitian scientists will start a 20-day research cruise off Haiti to address urgent questions about the workings of the great Jan. 12 earthquake, and the possibility of continuing threats. They hope to gather sonar images, sediments and other evidence from the seafloor that might reveal hidden structures, how they have moved,…
