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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 1,585 records · Page 88Linked to original sources
USGS1994

Geologic maps of the Olympus Mons region of Mars

Olympus Mons is one of the broadest volcanoes and certainly the tallest in the Solar System. It has been extensively described and analyzed in scientific publications and frequently noted in the popular and nontechnical literature of Mars. However, the first name given to the feature-Nix Olympica (Schiaparelli, 1879)-was based on its albedo, not its size, because early telescopic observations of Mars revealed only albedo features and not topography (lnge and others, 1971). After Mariner 9 images acquired in 1971 showed that this albedo feature coincides with a giant shield volcano (McCauley and others, 1972), the name Olympus Mons was adopted for the shield to distinguish it from the albedo feature. Olympus Mons is one of the most photographed features on the planet. The Mariner 9 spacecraft obtained 126 images of Olympus Mons with resolutions of 60 m/pixel to 2.5 km/pixel. Later, the two Viking orbiters greatly enlarged this dataset, acquiring more than 2,150 images of the Olympus Mons region at various resolutions and altitudes; 925 images have resolutions of better than 50 m/pixel. More than 150 of the Viking images provide stereoscopic coverage of the shield region (Blasius and others, 1982).

IMAP↗
USGS1995

Geologic map of the Duncan Peak and southern part of the Cisco Grove 7 1/2' quadrangles, Placer and Nevada Counties, California

This map covers an area of 123 km 2 on the west slope of the Sierra Nevada, an uplifted and west-tilted range in eastern California (fig. 1). The area is located 20 km west of Donner Pass, which lies on the east escarpment of the range, and about 80 km east of the Great Valley Province. Interstate Highway 80 is the major route over the range at this latitude and secondary roads, which spur off from this highway, provide access to the northern part of the area. None of the secondary roads crosses the deep canyon cut by the North Fork of the American River, however, and access to the southern part of the area is provided by logging roads that spur off from the Foresthill Divide Road that extends east from Auburn to the Donner Pass area (fig. 1).

California↗