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Water has not run across Antarctica ’s Friis Hills for 14 million years , researchers cover Tuesday ( Oct. 29 ) at the Geological Society of America ’s annual merging in Denver .
The Friis Hills rise 2,000 foot ( 600 meters ) aboveAntarctica’sTaylor Valley , one of the " Dry Valleys " west of McMurdo Sound . Fossils show tundra moss and a lake once cover the directly - topped hills , when Earth ’s clime was warm more than 14 million class ago . Now , thanks to blocking by nearby great deal , cold-blooded temperature and strong winds that suck wet from the gentle wind , the capably named Dry Valleys receive little to no measurable pelting or Baron Snow of Leicester . ( Sometimes , snow float in from nearby hills . )
Friis Hills in Antarctica, one of the driest places on Earth.
To guess ancient rainfall amounts , Rachel Valletta , a graduate student at the University of Pennsylvania , looked for traces of a radioactive isotope calledberyllium-10 in lake sediments on the Friis Hills . This rarefied beryllium isotope , which has more neutron than the static translation , form when cosmic rays collide with O and nitrogen atoms . Beryllium-10 decays on a predictable time scale , allowing geochemists to estimate the long time of sediments take the isotope . [ The 10 Driest Places on Earth ]
Valletta tested the lake deposit for meteorological beryllium-10 — isotopes created in Earth ’s atmosphere and carried down to the airfoil by rainfall . She measured the levels at musical interval from the open down to 2 feet ( 60 cm ) below ground . At the deepest levels , the isotope was undetectable . This imply the beryllium-10 buried with the sediments zillion of geezerhood ago has completely decompose away , and no body of water has filter into the flat coat to replace it .
" We would have expected greater concentrations of Be had there been water flow over the surface , " Valletta recount LiveScience ’s OurAmazingPlanet . " Concentrations this Sir David Low do indeed support the fact that there has been no Earth’s surface weewee present tense " since the sediment were deposited , she said .
Friis Hills in Antarctica, one of the driest places on Earth.
The termination also suggest that this part ofTaylor Valleyhas been extremely dry for a very long clock time . Other evidence for little to no rainfall or snowfall falling on Friis Hills let in ash layer with no chemical weathering triggered by urine , Valletta allege . " I ca n’t say that there has been no precipitation , " Valletta aver . " But hastiness has been extremely low in this area . "
Valetta plan to use the beryllium-10 data point to help track erosion rates at Friis Hills and better estimate the starting time of Antarctica ’s current cold , dry climate .
Fossils found in ancient lake sediments on Antarctica’s Friis Hills.
