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Appalachian sands covered North America

Appalachian sands covered North America
trefwoorden: VS - Appalachen - zand - Navajo
The vast and mysterious Sahara-like sea of sand that once covered much of western North America came from an Amazon-like river that brought sand from the far-off Appalachians, not the Rockies, geologists said.
Thick remnants of the 190 million-year-old sand sea are found today in the scenic, buff-colored Navajo Sandstone cliffs of Utah, New Mexico, Arizona and Colorado. By studying durable minerals in the sandstone called zircons, Yale University geologist Jeffrey Rahl and his colleagues have found a chemical signature that reveals their surprisingly distant Appalachian origin. Rahl's report is in the September issue of the journal Geology.
"People had speculated that the early Rockies were the source [of the Navajo Sandstone]," said geologist Jeffrey Rahl of Yale University. "This was definitely not what we were expecting."

Lees verder bij: Discovery News (12 september 2003)