Acasta Gneiss
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The Acasta Gneiss is a rock outcrop of Archaean tonalite gneiss in the Northwest Territories, Canada. It is the oldest known crustal rock outcrop in the world. The Acasta Gneiss is named for the nearby Acasta River east of Great Slave Lake some 350 km north of Yellowknife. The rock exposed in the outcrop formed just over four billion (4 x 109) years ago; an age based on radiometric dating of zircon crystals.
In 2003 a team from the Smithsonian Institute collected a four-tonne boulder of Acasta Gneiss for display outside the National Museum of the American Indian in Washington, D.C.
The Acasta outcrop is found in a remote area of the Tlicho land settlement.
See also
External links
- [Ancient rock begins pilgrimage to museum]
- [ANCIENT CONTINENT OPENS WINDOW ON THE EARLY EARTH Science, December 17,1999]
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