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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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ScienceShot: Underground Rain Gauge?
12 June 2012 5:25 pm
Cave formations known as stalactites are often pretty, but they also may provide clues about past climates. In some instances, the surfaces of these icicle-like accumulations of minerals sport series of rings, ripples, and ridges (image) which are typically spaced between 5 and 10 millimeters apart. A new analysis suggests that the ridges develop when the steady flow of mineral-rich water is disturbed as it runs over tiny imperfections in a stalactite's surface. Small eddies in the flow lead to increased deposition of calcium carbonate at certain regularly spaced locations, researchers reported online this month in Physical Review Letters. Cross sections through stalactites reveal that even though water is flowing downward, these regular ridges, or crenulations, migrate upward as years pass because deposition of minerals tends to take place on the upstream side of the ridges. According to the team's model, the rate at which the crenulations migrate upward doesn't depend on the temperature in the cave or the concentration of dissolved minerals in the water. However, the migration rate does depend on the flow rate of the water across a stalactite's surface—a hint that scientists might be able to use crenulated stalactites as rain gauges for past eras, since the amount of water dripping down a stalactite's surface typically depends on the precipitation falling on the surface above the cave.
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