June 3, 2010

Ancient Meteorite Discovered In Oregon

Scientists recently announced that a 40-pound ancient meteorite has been discovered in north central Oregon.

According to researchers studying the stone, the rock found in a ditch along a stretch of road is from outer space and traveled across millions of miles and billions of years to reach Earth.

Donald Wesson and his wife Debbie picked up the cone-shaped meteorite during the fall of 1999 as they drove through Oregon's wheat country on their way home to Washington.  This is the fifth meteorite discovered in the northwestern state.

The space rock remained unidentified for another decade as it rested in Wesson's garden.

After sitting anonymously on Earth's surface for thousands of years, the space rock stayed beneath a deck at the Wesson's house, visited a country fair and passed through two universities before its true identity was seen.

"It was probably plowed up by a farmer and tossed to the side of the road," said Dick Pugh, a geologist at Portland State University in Oregon. "There is even evidence that the rock was hit by a plow."

Wesson became curious after watching a television show about meteorites.  He then spoke with a member of the Southern Washington Mineralogical Society at a local country fair in Castle Rock, Washington in the summer of 2009.

The Cascadia Meteorite Laboratory at Portland State University later classified the Morrow Country meteorite as an L6 ordinary chondrite that had been highly shocked (S5) but minimally weathered (W1).

According to Melinda Hutson, a planetary scientist at Portland State University, the latest find represents a relatively common type of meteorite.  She added that it has several intriguing features.

"The meteorite isn't significantly weathered, but it has a distinctive yellow tint caused by weathering unlike that seen in meteorites recovered from deserts in Africa or Antarctica," Hutson told Space.com. "Also, it has beautiful shock veins and glass, caused by a major collision in space."

The Nomenclature Committee of the Meteoritical Society approved both the name and classification of the meteorite.  A type sample now resides with Portland State University.

Meteorites can easily blend in with Oregon's terrain.  Previously, only four meteorites had been discovered in Oregon, including Sam's Valley, found in 1984; Willamette, found in 1902; Klamath Falls, found in 1952; and Salem, found in 1981.  Three of these are iron meteorites, while Salem is a stony meteorite.

"In a way, I'm not surprised at all by this discovery," Alex Ruzicka, a planetary scientist at Portland State University told Space.com. "With our vigorous outreach effort I always knew the lab would help to recover more meteorites from Oregon, I just didn't know when. Maybe this will be the start of many more to come"


Image 1: A closer view of the Morrow County meteorite, showing the sculpted surface texture caused by passage through the Earth's atmosphere. The meteorite has a distinctive yellowish color caused by mild weathering on Earth. A portion of the meteorite at bottom right has been removed for study. At the top, another portion is missing, which was removed before Mr. Wesson found the rock, possibly by a farm plow. Credit: Portland State University

Image 2: Morrow County as observed in a thin section with a polarizing microscope. The brightly colored minerals at center are composed of olivine. Credit: Portland State University


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