Object Record

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Catalog Number 2005.012.0034
Accession number 2005.012.
Object Name Tephra
Description A small clear glass baby food jar with blue metal lid filled with Mount St. Helens volcanic ash. "Mt. Saint Helens Eruption / May 18, 1980 / Collected at Moses Lake, Wa." on typed label affixed to jar.

From http://volcanoes.usgs.gov: "Small jagged pieces of rocks, minerals, and volcanic glass the size of sand and silt (less than 2 millimeters (1/12 inch) in diameter) erupted by a volcano are called volcanic ash. Very small ash particles can be less than 0.001 millimeters (1/25,000th of an inch) across. Volcanic ash is not the product of combustion, like the soft fluffy material created by burning wood, leaves, or paper. Volcanic ash is hard, does not dissolve in water, is extremely abrasive and mildly corrosive, and conducts electricity when wet. Volcanic ash is formed during explosive volcanic eruptions. Explosive eruptions occur when gases dissolved in molten rock (magma) expand and escape violently into the air, and also when water is heated by magma and abruptly flashes into steam. The force of the escaping gas violently shatters solid rocks. Expanding gas also shreds magma and blasts it into the air, where it solidifies into fragments of volcanic rock and glass. Once in the air, wind can blow the tiny ash particles tens to thousands of kilometers away from the volcano."
Collection JoAn O'Leary Collection
Date 05/18/1980
Source O'Leary, JoAn
Collector George O'Leary
Material Glass/Metal/Ash
People O'Leary, George
O'Leary, JoAn
Search Terms Moses Lake
Mount St. Helens