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High-Resolution Aeromagnetic Survey of the Cle Elum Area, Washington

May 25, 2020

This data release provides access to a low-altitude, aeromagnetic survey of a part of central Washington centered approximately 22 km west-southwest of Ellensburg. The survey includes the cities of Ellensburg, Cle Elum, and Yakima and is referred to as the Cle Elum aeromagnetic survey. The Cle Elum aeromagnetic survey extends from the Columbia Plateau westward to the eastern Cascade Range and illuminates magnetic anomalies associated with folds and faults of the Yakima folds, including the Umtanum Ridge, Saddle Mountains, and Frenchman Hills anticlines. These data were acquired during August and September, 2008, by Firefly Aviation, Ltd., working under contract to the U.S. Geological Survey. Total magnetic field values were acquired using a fixed-wing aircraft flown at a target elevation 150 m above terrain. The nominal flying height was based on a best fit, pre-planned, three-dimensional draped surface 155 m above terrain, subject to aircraft climb and descent limitations. Flight lines were spaced 400 m apart and directed east-west. Tie lines were spaced 4000 m apart, and directed north-south. A total of 26,680 line-kilometers were acquired. The details of the Cle Elum aeromagnetic survey are described in the document, CleElem_Tech_report.pdf available for download in this data release.