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Person

James E O'connor

Acting Center Director
Geology, Minerals, Energy, and Geophysics Science Center

Email: oconnor@usgs.gov
Office Phone: 503-251-3222
Fax: 503-251-3470
ORCID: 0000-0002-7928-5883

Supervisor: Eric G Reichard
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This data release provides access to a low-altitude aeromagnetic survey flown over a part of the Cascade Range of the US Pacific Northwest, approximately centered over the town of Cascade Locks, Oregon. The Cascade Locks magnetic survey encompasses two large stratovolcanoes of the Cascade Range: Mt. Hood (3426 m) in Oregon and Mt. Adams (3742 m) in Washington. Data were acquired between October 17, 2021, and February 26, 2022, by KBM Resources Group, Thunder Bay, Ontario, Canada, working under contract to the U.S. Geological Survey. The survey is underlain by a diverse magnetic terrane, including Miocene flood basalts of the Columbia River Basalt Group and Tertiary to Quaternary volcanic and intrusive rocks of the...
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Forty years ago, the demolition of large dams was mostly fiction, notably plotted in Edward Abbey's novel The Monkey Wrench Gang. Its 1975 publication roughly coincided with the end of large-dam construction in the United States. Since then, dams have been taken down in increasing numbers as they have filled with sediment, become unsafe or inefficient, or otherwise outlived their usefulness ( 1) (see the figure, panel A). Last year's removals of the 64-m-high Glines Canyon Dam and the 32-m-high Elwha Dam in northwestern Washington State were among the largest yet, releasing over 10 million cubic meters of stored sediment. Published studies conducted in conjunction with about 100 U.S. dam removals and at least 26...
Categories: Publication; Types: Citation
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This data release consists of high quality georeferenced orthophoto mosaics of a 160 kilometer long portion of the Columbia River between Portland and The Dalles, Oregon created from aerial photographs collected in 1935 by the U.S. Army Corps of Engineers. The dataset comprises three GeoTIFF files, each covering about 40-60 kilometers. This metadata document summarizes the entire data release. See attached metadata records for information on the individual mosaics.
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Recent decades have seen a marked increase in the number of dams removed in the United States. Investigations following a number of removals are beginning to inform how, and how fast, rivers and their ecosystems respond to released sediment. Though only a few tens of studies detail physical responses to removals, common findings have begun to emerge. They include: (1) Rivers are resilient and respond quickly to dam removals, especially when removals are sudden rather than prolonged. Rivers can swiftly evacuate large fractions of reservoir sediment (≥50% within one year), especially when sediment is coarse grained (sand and gravel). The channel downstream typically takes months to years--not decades--to achieve a...
Categories: Publication; Types: Citation
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This dataset represents a variety of scientific measurements of basalt rock outcrops in central Oregon, United States. It consists of field observations, geochemical measurements, paleomagnetic directional measurements, magnetic susceptibility, and geochronology data (Ar-Ar methodology). This dataset was collected from 2014-2022 by the authors.
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