A U.S. study suggests northern Oregon's Blue Mountains may have originated from the Klamath Mountains of southern Oregon and the Sierra Nevada of California.
The finding comes from radioactive isotope dating of grains of the mineral zircon taken from Blue Mountain basins in northeastern Oregon. The approximate ages of the Blue Mountain zircon grains match the ages of rocks to the south in the Klamath and Sierra Nevada mountains.
University of Oregon doctoral student Todd LaMaskin said the westernmost chain of U.S. mountains and basins might have been continuous from California to Oregon millions of years ago.
"So we think at this point that we may have the most definitive evidence to date that during in Jurassic time there was a connection between the rocks of the Blue Mountains and the northern Sierra Nevadas and eastern Klamath ranges," said LaMaskin.
He and his adviser, Professor Rebecca Dorsey, along with Washington State University Professor Jeffrey Vervoort presented their findings Monday in Denver during the annual meeting of the Geological Society of America.
Copyright 2007 by United Press International
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