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At least 1,459 records · Page 81Linked to original sources
USGS2001

Geologic map and map database of the Spreckels 7.5-minute Quadrangle, Monterey County, California

Introduction The Spreckels quadrangle lies at the north end of the Sierra de Salinas and extends from the Salinas Valley on the northeast across Los Laurelles Ridge south to Carmel Valley, an intermontane valley that separates the Santa Lucia Range from the Sierra de Salinas (fig. 1). The Toro Regional Park occupies the east-central part of the quadrangle, whereas the former Fort Ord Military Reservation covers the northwestern part of the area and is the probable locus of future development. Subdivisions largely occupy the older floodplain of Toro Creek and the adjacent foothills, with less dense development along the narrower canyons of Corral de Tierra and San Benancio Gulch to the south. The foothills southwest of the Salinas River are the site of active residential development. Geologically, the study area has a crystalline basement of Upper Cretaceous granitic rocks of the Salinian block and older metasedimentary rocks of the schist of the Sierra de Salinas of probable Cretaceous age. Resting nonconformably upon these basement rocks is a sedimentary section that ranges in age from middle Miocene to Holocene and has a composite thickness of as much as 1,200 m. One of the purposes of the present study was to investigate the apparent lateral variation of the middle to upper Miocene sections from the typical porcelaneous and diatomaceous Monterey Formation of the Monterey and Seaside quadrangles to the west (Clark and others, 1997) to a thick marine sandstone section in the eastern part of the Spreckels quadrangle. Liquefaction, which seriously affected the Spreckels area in the 1906 San Francisco earthquake (Lawson, 1908), and landsliding are the two major geological hazards of the area. The landslides consist mainly of older large slides in the southern and younger debris flows in the northern part of the quadrangle. This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (skmf.txt, skmf.pdf, or skmf.ps), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗
USGS1994

Geologic map of science study area 4, Chasma Boreale Region of Mars

This map is one is a series of 1:500,000 scale maps initiated by the National Aeronautics and Space Administration to investigate Science Study Areas (selected area of scientific interest) on Mars (fig. 1). The Chasma Boreale region merits detailed geologic study because it contains parts of (1) the north polar ice cap, which is composed of water ice with lesser amounts of carbon dioxide; (2) the layered terrain that recorded climatic and atmospheric changes on Mars during the Amazonian Period; and (3) the enigmatic low-lying polygonal patterned terrain. The map was compiled on a composite of three 1:500,000-scale photomosaic bases (U.S. Geological Survey, 1986a, b, c), each of which is the summer scene of a two-sheet set that includes a spring scene. (Summer scenes, acquired when the north polar ice cap is smallest, show the greatest extent of underlying materials. However, spring scenes that show more detail in specific areas were also used.) Map units (including crater materials) and contacts are generally consistent with those of Howard and others (1982), Dial (1984), and Tanaka and Scott (1987) except where revised on the basis of higher resolution Viking images. Several Viking images were computer enhanced for our mapping.

IMAP↗
USGS1999

Geologic map of the Galaxias quadrangle (MTM 35217) of Mars

The Galaxias region (MTM 35217) is one of a series of 1:500,000-scale science study areas on Mars sponsored by NASA's Planetary Geology and Geophysics Program. Situated near the northern limit of lava flows associated with Elysium Mons, this region includes a mixture of volcanic and nonvolcanic terrains. The region is also of interest for the fluvial systems that originate along the distal margins of the Elysium lava flows. Resolution of Viking Orbiter images used to prepare the base map ranges from 40 to 160 m/pixel. High-resolution frames (40 to 80 m/pixel) are found in the southeastern part of the map area and along the north edge of the quadrangle, but over half the quadrangle is included in medium-resolution frames (150 m/pixel). Two 8 m/pixel, very high resolution scenes are available (see fig. 1). Interpretation is complicated by variable resolution and sun angles that vary from east to west illumination on different images. Mapping methods and principles are adapted from those developed for lunar photogeologic mapping by Shoemaker and Hackman (1962), refined by Wilhelms (1972), and successfully applied by many workers to a variety of planetary surfaces. Mapping units are distinguished by topography and texture and are ranked by relative age on the basis of superposition and transection relations. Material units are assigned to time-stratigraphic systems defined by Scott and Carr (1978) and Tanaka (1986). This area is included within earlier maps that used Mariner 9 images at 1:5,000,000 scale (Elston, 1979) and globally at 1:25,000,000 scale (Scott and Carr, 1978). Regional maps based on the much higher resolutions of Viking Orbiter allowed more detailed discrimination of materials by Greeley and Guest (1987) at 1:15,000,000 scale and Tanaka and others (1992) at 1:5,000,000 scale. Some map units on this 1:500,000-scale map correspond to, or are partially equivalent to, units on the larger scale maps of Greeley and Guest (1987) and Tanaka and others (1992). Established terminology is used where feasible, but the scale of this map requires that some new units be introduced and that some previous terminology be redefined. Photogeologic methods are limited; therefore, more than one geologic explanation is given for some material units that do not readily lend themselves to an unequivocal interpretation.

IMAP↗
USGS2014

Geologic map of the Gila Hot Springs 7.5' quadrangle and the Cliff Dwellings National Monument, Catron and Grant Counties, New Mexico

The Gila Hot Springs quadrangle is of geologic interest with respect to four major features, which are: 1) The caves of the Gila Cliff Dwellings National Monument 2) The hot springs associated with the faults of the Gila Hot Springs graben 3) The Alum Mountain rhyolite dome and eruptive center 4) A proposed segment of the southeastern wall of the Gila Cliff Dwellings caldera The Gila Cliff Dwellings National Monument consists of two tracts. The caves that were inhabited by the Mogollon people in the 14th century are in the main tract near the mouth of Cliff Dweller Canyon in the Little Turkey Park 7.5' quadrangle adjoining the northwest corner of the Gila Hot Springs quadrangle. The second tract includes the Cliff Dwellings National Monument Visitor Center at the confluence of the West and Middle Forks of the Gila River in the northwest corner of the Gila Hot Springs quadrangle. Both quadrangles are within the Gila National Forest and the Gila Wilderness except for a narrow corridor that provides access to the National Monument and the small ranching and residential community at Gila Center in the Gila River valley. The caves in Cliff Dweller Canyon were developed in the Gila Conglomerate of probable Miocene? and Pleistocene? age in this area by processes of lateral corrosion and spring sapping along the creek in Cliff Dweller Canyon. The hot springs in the Gila River valley are localized along faults in the deepest part of the Gila Hot Springs graben, which cuts diagonally northwest-southeast across the central part of the quadrangle. Some of the springs provide domestic hot water for space heating and agriculture in the Gila River valley and represent a possible thermal resource for development at the Cliff Dwellings National Monument. The Alum Mountain rhyolite dome and eruptive center in the southwestern part of the quadrangle is a colorful area of altered and mineralized rocks that is satellitic to the larger Copperas Canyon eruptive center, both being part of the composite Copperas Creek volcano, or volcanic complex in the Copperas Peak quadrangle to the south. The altered rocks of the Alum Mountain eruptive center have been prospected by means of several short adits, or tunnels, for alum, a mixture of the iron and aluminum sulfate minerals: alunite and halotrichite. A fault on the west side of the Gila River, opposite the hot springs in the south-central part of the map area, just north of Alum Mountain, is tentatively interpreted as a segment of the wall of the Gila Cliff Dwellings caldera. The fault, which dips about 55 degrees northwest, has a footwall of the andesitic and dacitic lava flows and flow breccias of Gila Flat. The hanging wall consists of Bloodgood Canyon Tuff overlain by Bearwallow Mountain Andesite flows. However, these rocks are not faulted against the older rocks, but apparently abut and locally overlap the footwall. These are the major geologic features of the quadrangle, about three quarters of which is covered by Bearwallow Mountain Andesite lava flows and overlying volcaniclastic rocks of the Gila Conglomerate.

New Mexico↗
USGS2011

Geologic map of the eastern half of the Vail 30' x 60' quadrangle, Eagle, Summit, and Grand Counties, Colorado

Recent mapping and geochronologic studies for the eastern half of the Vail 1:100,000-scale quadrangle have significantly improved our understanding of (1) Paleoproterozoic history of the basement rocks of the Gore Range and Williams Fork Mountains (western margin of the Front Range), (2) the Late Paleozoic history of the Gore fault system, (3) Laramide contractional tectonism, including deformation along the Gore fault and Williams Range thrust, (4) Oligocene and younger extensional history of the Blue River half graben (The northern extent of the Rio Grande rift), and (5) late Neogene and Quaternary surficial history. The recently active Gilman mining district, a major producer of zinc and lead, is in the southwestern corner of the map area. Marine sediments and mafic to felsic volcanic rocks deposited between about 1,740 and 1,780 m.y. were generally metamorphosed to amphibolite grade and intruded and deformed by mostly calc-alkalic granitic rocks during an orogenic episode that lasted about 110 m.y. The distribution of well-studied Upper Cambrian to thick Upper Cretaceous platform sediments is now greatly improved, which allows a better definition of the late Paleozoic uplift, erosion, and flanking sedimentation of the ancestral Front Range. Detailed mapping has also better defined the geometry of Late Cretaceous to early Tertiary Laramide deformation along both the Gore fault system and Williams Range thrust, as well as increased understanding of the details of mostly Neogene extension along the Blue River normal fault system (the western margin of the Blue River half graben). Scarps along the latter fault system indicate movement may be as young as Holocene. Detailed mapping of surficial deposits has defined and described (1) six ages of terrace alluvium, (2) three general ages of landslides, (3) glacial and periglacial deposits, and (4) fan, pediment, talus, and debris-flow deposits. The map is intended as a database for a variety of land-use and scientific purposes, including (1) assessment of geologically stable building sites, (2) planning for road and highway construction, (3) assessment of groundwater resources, (4) assessment of mineral resources, (5) determining geologic-hazard potential (flooding, landslide, rockfall, and seismic risk), (6) evaluating the structure of the northern Rio Grande rift in the Blue River valley, (7) improvement in understanding of the sedimentary section, which spans the period from the Cambrian to the Holocene, and (8) new insights into the geologic history of the Proterozoic basement rocks, including a number of new radiometric dates.

Scientific Investigations Map↗