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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 865 records · Page 48Linked to original sources
USGS1989

Draft generalized geologic map of the Chandler Lake Quadrangle, north-central Alaska

Release of this map in open-file is in response to recent requests for geological information in the central Brooks Range and adjacent Arctic foothills. Upcoming State of Alaska oil and gas lease sales, the White Hills Sale Area 61 (January, 1992), the North Slope Foothills Sale Area 57 (September, 1993), and the Nanushuk Sale Area 77 (May, 1993) are stimulating interest in the geology of the central Arctic foothills. Geological field programs in preparation for lease sales are beginning this summer. Western Geophysical Company has made 800 line miles of reflection seismic data available for the upcoming lease sales, 400 line miles shot during the winter of 1986-87 and 400 line miles shot during the winter of 1988-89. The recently completed geophysical and ongoing geological surveys have prompted requests for timely release of geological information on the central Arctic foothills.

Alaska↗
USGS2002

Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data

A high-resolution aeromagnetic survey of the Puget Lowland shows details of the Seattle fault zone, an active but largely concealed east-trending zone of reverse faulting at the southern margin of the Seattle basin. Three elongate, east-trending magnetic anomalies are associated with north-dipping Tertiary strata exposed in the hanging wall; the magnetic anomalies indicate where these strata continue beneath glacial deposits. The northernmost anomaly, a narrow, elongate magnetic high, precisely correlates with magnetic Miocene volcanic conglomerate. The middle anomaly, a broad magnetic low, correlates with thick, nonmagnetic Eocene and Oligocene marine and fluvial strata. The southern anomaly, a broad, complex magnetic high, correlates with Eocene volcanic and sedimentary rocks. This tripartite package of anomalies is especially clear over Bainbridge Island west of Seattle and over the region east of Lake Washington. Although attenuated in the intervening region, the pattern can be correlated with the mapped strike of beds following a northwest-striking anticline beneath Seattle. The aeromagnetic and geologic data define three main strands of the Seattle fault zone identified in marine seismic-reflection profiles to be subparallel to mapped bedrock trends over a distance of >50 km. The locus of faulting coincides with a diffuse zone of shallow crustal seismicity and the region of uplift produced by the M 7 Seattle earthquake of A.D. 900-930.

Washington↗
USGS1973

Stratigraphic studies: Part D: geologic map of the northern Crisium region

Apollo 17 metric photographs (fig. 29-26) provide the best available coverage for geologic interpretation of northern Mare Crisium and the northern Crisium basin. The area was covered previously by low-resolution telescopic and Lunar Orbiter IV photographs and by oblique, high-illumination, or low-resolution photographs from earlier Apollo missions. One region in particular, between Alhazen Crater and longitude 66° E, had previously been covered very poorly. The Apollo 17 photographs provide excellent monoscopic (fig. 29-26) as well as stereoscopic viewing because of the favorably low Sun illuminations (15° to 49°). These new photographic data allow the geology of the basin, the mare, and other nearby terrains to be reevaluated. This reexamination together with data from continuing Moon-wide photogeologic studies and analyses of returned rocks from Apollo landing sites, has produced a simple evolutionary picture of the region, expressed by fewer map units and explained by fewer basic processes than previously thought necessary (refs. 29-35 and 29-45 to 29-48).

Book chapter↗