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At least 91 records · Page 5Linked to original sources
USGS2024

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within parts of Bandera and Kendall Counties, Texas

The karstic Edwards and Trinity aquifers are classified as major sources of water in south-central Texas by the Texas Water Development Board. During 2019–23 the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, mapped and described the geology and hydrostratigraphy of the rocks composing the Edwards and Trinity aquifers within parts of Bandera and Kendall Counties from field observations of the surficial expressions of the rocks. The thicknesses of the mapped lithostratigraphic and hydrostratigraphic units were also estimated from field observations in the study area. The Cretaceous rocks in the study area are part of the Trinity Group and Edwards Group. The groups, formations, and members are composed primarily of layers of marls, shales, and limestones. The limestones are composed of mudstone through grainstone, framestone and boundstone, dolomite, and argillaceous and evaporitic rocks. The principal structural feature in the study area is the Balcones fault zone. The Balcones fault zone is the result of late Oligocene and early Miocene extensional faulting and fracturing that was a result of the eastern Edwards Plateau uplift. In the Balcones fault zone, most of the faults in the study area are high-angle to vertical, en echelon, normal faults that are predominantly downthrown to the southeast. Hydrostratigraphically, the rocks exposed in the study area are those that contain the Edwards aquifer, the upper zone of the Trinity aquifer, and the middle zone of the Trinity aquifer. Descriptions of the hydrostratigraphic units, thicknesses, hydrologic function, porosity types, and field identification and observations are provided, including those for the informal Bandera and Love Creek hydrostratigraphic units of the Edwards aquifer, which were identified through the mapping for this study.

Texas↗
USGS2006

Geologic map of the Utukok River quadrangle, Alaska

This map is a product of the USGS Digital Geologic Maps of Northern Alaska project, which captures in digital format quadrangles across the entire width of northern Alaska. Sources include geologic maps previously published in hardcopy format and recent updates and revisions based on field mapping by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey. Individual quadrangles are digitized at either 1:125,000 or 1:250,000 depending on the resolution of source maps. The project objective is to produce a set of digital geologic maps with uniform stratigraphic nomenclature and structural annotation, and publish those maps electronically.

Alaska↗
USGS2008

Revised Geologic Map of the Fort Garland Quadrangle, Costilla County, Colorado

The map area includes Fort Garland, Colo., and the surrounding area, which is primarily rural. Fort Garland was established in 1858 to protect settlers in the San Luis Valley, then part of the Territory of New Mexico. East of the town are the Garland mesas (basalt-covered tablelands), which are uplifted as horsts with the Central Sangre de Cristo fault zone. The map also includes the northern part of the Culebra graben, a deep structural basin that extends from south of San Luis (as the Sanchez graben) to near Blanca, about 8 km west of Fort Garland. The oldest rocks exposed in the map area are early Proterozic basement rocks (granites in Ikes Creek block) that occupy an intermediate structural position between the strongly uplifted Blanca Peak block and the Culebra graben. The basement rocks are overlain by Oligocene volcanic and volcaniclastic rocks of unknown origin. The volcanic rocks were buried by a thick sequence of basin-fill deposits of the Santa Fe Group as the Rio Grande rift formed about 25 million years ago. The Servilleta Basalt, a regional series of 3.7?4.8 Ma old flood basalts, was deposited within sediment, and locally provides a basis for dividing the group into upper and lower parts. Landslide deposits and colluvium that rest on sediments of the Santa Fe Group cover the steep margins of the mesas. Exposures of the sediment beneath the basalt and within the low foothills east of the Central Sangre de Cristo fault zone are comprised of siltstones, sandstones, and minor fluvial conglomerates. Most of the low ground surrounding the mesas and in the graben is covered by surficial deposits of Quaternary age. The alluvial deposits are subdivided into three Pleistocene-age units and three Holocene-age units. The oldest Pleistocene gravel (unit Qao) is preserved as isolated remnants that cap high surfaces north and east of Fort Garland. The primary geologic hazards in the map area are from earthquakes, landslides, and localized flooding. The Central Sangre de Cristo fault zone shows evidence for latest Pleistocene to possible early Holocene movement. The landslides may have seismogenic origins; that is, they may be stimulated by strong ground shaking during large earthquakes. This revised geologic map is based on previous mapping by Wallace (1997) and new mapping, primarily of the Quaternary deposits, by Machette.

Scientific Investigations Map↗
USGS2007

Water-level altitudes 2007 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2006 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

This report, done in cooperation with the Harris-Galveston Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District, is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston, Texas, region. The report contains 18 sheets and 17 tables: 3 sheets are maps showing current-year (2007) water-level altitudes for each aquifer, respectively; 3 sheets are maps showing 1-year (2006-07) water-level changes for each aquifer, respectively; 3 sheets are maps showing 5-year (2002-07) water-level changes for each aquifer, respectively; 4 sheets are maps showing long-term (1990-2007 and 1977-2007) water-level changes for the Chicot and Evangeline aquifers, respectively; 1 sheet is a map showing long-term (2000-2007) water-level change for the Jasper aquifer; 2 sheets are revisions of previously published water-level-altitude maps for the Jasper aquifer for 2000 and 2002, respectively; 1 sheet is a map showing site locations of borehole extensometers; and 1 sheet comprises graphs showing measured compaction of subsurface material at the sites from 1973 or later through 2006, respectively. Tables listing the data used to construct the aquifer-data maps and the compaction graphs also are included.

Texas↗
USGS2008

Geologic map of the Clark Peak quadrangle, Jackson and Larimer Counties, Colorado

The Clark Peak quadrangle encompasses the southern end of the Medicine Bow Mountains and the northernmost end of the Mummy Range. The Continental Divide traverses the map area and Highway 14 cross the Divide at Cameron Pass, in the southeastern corner of the map. Approximately the eastern half of the map, and a few areas to the west, are underlain by Early Proterozoic plutonic and metamorphic rocks. Most of these basement rocks are part of the ~1,715 Ma Rawah batholith, composed mostly of pinkish, massive to moderately foliated monzogranite and granodiorite intruded by numerous, large pegmatite- aplite bodies. The metamorphic rocks, many of which form large inclusions in the granitic rocks of the Rawah batholith, include biotite-hornblende gneiss, hornblende gneiss, amphibolite, and biotite schist. The crystalline basement rocks are thrust westward along the Medicine Bow thrust over a sequence of sedimentary rocks as old as the Upper Permian Satanka Shale. The Satanka Shale, Middle and Lower Triassic Chugwater group, and a thin sandstone tentatively correlated with the Lower Jurassic and Upper Triassic Jelm Formation are combined as one map unit. This undivided unit is overlain sequentially upward by the Upper Jurassic Sundance Formation, Upper Jurassic Morrison Formation, Lower Cretaceous Dakota Group, Upper and Lower Cretaceous Benton Group, Upper Cretaceous Niobrara Formation, and the Eocene and Paleocene Coalmont Formation. The Late Cretaceous to early Eocene Medicine Bow thrust is folded in places, and several back thrusts produced a complicated thrust pattern in the south part of the map. Early Oligocene magmatism produced rhyolite tuff, dacite and basalt flows, and intermediate dikes and small stocks. A 40Ar/39Ar date on sanidine from one rhyolite tuff is ~28.5 Ma; a similar whole-rock date on a trachybasalt is ~29.6 Ma. A very coarse, unsorted probably pre-Quaternary ridge-top diamicton crops out in the southern part of the quadrangle. Numerous glacial deposits (mostly of Pinedale age), rock glaciers, block-slope deposits, landslide deposits, talus deposits, fan deposits, colluvium, and alluvium comprise the surficial deposits of the map area.

Colorado↗
USGS2016

Geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles, Clark County, Washington, and Multnomah County, Oregon

Introduction This is a 1:24,000-scale geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles in the States of Washington and Oregon. The map area is within the Portland Basin and includes most of the city of Vancouver, Washington; parts of Clark County, Washington; and a small part of northwestern Multnomah County, Oregon. The Columbia River flows through the southern part of the map area, generally forming the southern limit of mapping. Mapped Quaternary geologic units include late Pleistocene cataclysmic flood deposits, eolian deposits, and alluvium of the Columbia River and its tributaries. Older deposits include Miocene to Pleistocene alluvium from an ancestral Columbia River. Regional geologic structures are not exposed in the map area but are inferred from nearby mapping.

Oregon, Washington↗
USGS2017

Geologic map of the northern White Hills, Mohave County, Arizona

Introduction The northern White Hills map area lies within the Kingman Uplift, a regional structural high in which Tertiary rocks lie directly on Proterozoic rocks as a result of Cretaceous orogenic uplift and erosional stripping of Paleozoic and Mesozoic strata. The Miocene Salt Spring Fault forms the major structural boundary in the map area. This low-angle normal fault separates a footwall (lower plate) of Proterozoic gneisses on the east and south from a hanging wall (upper plate) of faulted middle Miocene volcanic and sedimentary rocks and their Proterozoic substrate. The fault is part of the South Virgin–White Hills Detachment Fault, which records significant tectonic extension that decreases from north to south. Along most of its trace, the Salt Spring Fault dips gently westward, but it also has north-dipping segments along salients. A dissected, domelike landscape on the eroded footwall, which contains antiformal salients and synformal reentrants, extends through the map area from Salt Spring Bay southward to the Golden Rule Peak area. The “Lost Basin Range” represents an upthrown block of the footwall, raised on the steeper Lost Basin Range Fault. The Salt Spring Fault, as well as the normal faults that segment its hanging wall, deform rocks that are about 16 to 10 Ma, and younger deposits overlie the faults. Rhyodacitic welded tuff about 15 Ma underlies a succession of geochemically intermediate to progressively more mafic lavas (including alkali basalt) that range from about 14.7 to 8 Ma, interfingered with sedimentary rocks and breccias in the western part of the map area. Upper Miocene strata record further filling of the extension-formed continental basins. Basins that are still present in the modern landscape reflect the youngest stages of extensional-basin formation, expressed as the downfaulted Detrital Valley and Hualapai Wash basins in the western and eastern parts of the map area, respectively, as well as the north-centrally located, northward-sagged Temple Basin. Pliocene fluvial and piedmont alluvial fan deposits record postextensional basin incision, refilling, and reincision driven by the inception and evolution of the westward-flowing Colorado River, centered north of the map area.

Arizona↗
USGS2018

Geologic map of the Nepenthes Planum Region, Mars

This map product contains a map sheet at 1:1,506,000 scale that shows the geology of the Nepenthes Planum region of Mars, which is located between the cratered highlands that dominate the southern hemisphere and the less-cratered sedimentary plains that dominate the northern hemisphere. The map region contains cone- and mound-shaped landforms as well as lobate materials that are morphologically similar to terrestrial igneous or mud vents and flows. This map is part of an informal series of small-scale (large-area) maps aimed at refining current understanding of the geologic units and structures that make up the highland-to-lowland transition zone. The map base consists of a controlled Thermal Emission Imaging System (THEMIS) daytime infrared image mosaic (100 meters per pixel resolution) supplemented by a Mars Orbiter Laser Altimeter (MOLA) digital elevation model (463 meters per pixel resolution). The map includes a Description of Map Units and a Correlation of Map Units that describes and correlates units identified across the entire map region. The geologic map was assembled using ArcGIS software by Environmental Systems Research Institute ( http://www.esri.com ). The ArcGIS project, geodatabase, base map, and all map components are included online as supplemental data.

Scientific Investigations Map↗
USGS2025

Geologic map of MTM −15032 and −20032 quadrangles, western Ladon basin, Mars

Our mapping efforts focused on the geomorphic terrains and geologic units contained within Mars Transverse Mercator (MTM) −15032 and −20032 quadrangles. These two quadrangles are located along the west side of Ladon basin and span lat −12.5° N. to −22.5° N. and long 325° E. to 330° E. The western part of Ladon basin and its bounding basin ring structures to the west preserved features that help to understand the long history of drainage across the Margaritifer Terra region of Mars. Our geologic map provides new insight into the extent of aqueous activity across western Ladon basin and the adjoining highlands, which includes the northern part of Ladon Valles, Arda Valles, numerous small valleys in the western highlands, and light-toned layered deposits associated with these fluvial features. The Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared (IR) daytime mosaic (100 meters per pixel) was used as the primary base map. We constructed the geologic map of western Ladon basin at 1:1,000,000 scale. We identified 20 geologic units in the map area, which we divided into the following groups: crater units; volcanic units; chaotic units; basin fill units; crater, valley, and channel units; and plateau and highlands units. We observed the following sequence of events: (1) formation of Ladon and Holden impact basins in the middle Noachian, producing a mountainous unit; (2) landscape degradation and infilling during the Late Noachian to Late Hesperian forming terra units; (3) formation of Ladon Valles in the Late Noachian to Early Hesperian by catastrophic flooding, producing channel units; (4) accumulation of sediments in the Late Noachian to Early Amazonian, forming basin fill units; (5) formation of a smooth crater fill unit during the Early to Late Hesperian; (6) deposition during the Late Hesperian to Early Amazonian, creating light-toned layered units within Ladon Valles, Ladon basin, and other smaller valley networks along the western uplands, as well as formation of a light-toned unit along some crater floors; (7) formation a of chaotic unit in the Early to Middle Amazonian, formation of alluvial fans in the Early Amazonian, and eruption of a volcanic unit in the Middle Amazonian; and (8) formation of craters throughout the geologic history of the map region.

Scientific Investigations Map↗
USGS2013

Geologic map of the Jam Up Cave and Pine Crest quadrangles, Shannon, Texas, and Howell Counties, Missouri

The Jam Up Cave and Pine Crest 7.5-minute quadrangles are located in south-central Missouri within the Salem Plateau region of the Ozark Plateaus physiographic province. About 2,400 to 3,100 feet (ft) of flat-lying to gently dipping Lower Paleozoic sedimentary rocks, mostly dolomite, chert, sandstone, and orthoquartzite, overlie Mesoproterozoic igneous basement rocks. Unconsolidated residuum, colluvium, terrace deposits, and alluvium overlie the sedimentary rocks. Numerous karst features, such as sinkholes, caves, and springs, have formed in the carbonate rocks. Many streams are spring fed. The topography is a dissected karst plain with elevations ranging from about 690 ft where the Jacks Fork River exits the northeastern corner of the Jam Up Cave quadrangle to about 1,350 ft in upland areas along the north-central edge and southwestern corner of the Pine Crest quadrangle. The most prominent physiographic feature is the valley of the Jacks Fork River. This reach of the upper Jacks Fork, with its clean, swiftly-flowing water confined by low cliffs and bluffs, provides one of the most beautiful canoe float trips in the nation. Most of the land in the quadrangles is privately owned and used primarily for grazing cattle and horses and growing timber. A large minority of the land within the quadrangles is publicly owned by the Ozark National Scenic Riverways of the National Park Service. Geologic mapping for this investigation was conducted in 2005 and 2006.

Missouri↗
USGS2008

Flood-plain study of the Upper Iowa River in the vicinity of Decorah, Iowa

The city of Decorah, Iowa, has experienced severe flooding from the Upper Iowa River resulting in property damage to homes and businesses. Streamflow data from two U.S. Geological Survey (USGS) streamflow-gaging stations, the Upper Iowa River at Decorah, Iowa (station number 05387500), located upstream from the College Drive bridge; and the Upper Iowa River near Decorah, Iowa (station number 05388000), at the Clay Hill Road bridge (locally known as the Freeport bridge) were used in the study. The three largest floods on the Upper Iowa River at Decorah occurred in 1941, 1961, and 1993, for which the estimated peak discharges were 27,200 cubic feet per second (ft3/s), 20,200 ft3/s, and 20,500 ft3/s, respectively. Flood-discharge information can be obtained from the World Wide Web at URL (uniform resource locator) http://waterdata.usgs.gov/nwis/ . In response to the need to provide the City of Decorah and other flood-plain managers with an assessment of the risks of flooding to properties and facilities along an 8.5-mile (mi) reach of the Upper Iowa River, the USGS, in cooperation with the City of Decorah, initiated a study to map 100- and 500-year flood-prone areas.

Iowa↗
USGS2012

Flood-inundation maps for the Suncook River in Epsom, Pembroke, Allenstown, and Chichester, New Hampshire

Digital flood-inundation maps for a 16.5-mile reach of the Suncook River in Epsom, Pembroke, Allenstown, and Chichester, N.H., from the confluence with the Merrimack River to U.S. Geological Survey (USGS) Suncook River streamgage 01089500 at Depot Road in North Chichester, N.H., were created by the USGS in cooperation with the New Hampshire Department of Homeland Security and Emergency Management. The inundation maps presented in this report depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage at Suncook River at North Chichester, N.H. (station 01089500). The current conditions at the USGS streamgage may be obtained on the Internet (http://waterdata.usgs.gov/nh/nwis/uv/?site_no=01089500&PARAmeter_cd=00065,00060). The National Weather Service forecasts flood hydrographs at many places that are often collocated with USGS streamgages. Forecasted peak-stage information is available on the Internet at the National Weather Service (NWS) Advanced Hydrologic Prediction Service (AHPS) flood-warning system site (http://water.weather.gov/ahps/) and may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. These maps along with real-time stream stage data from the USGS Suncook River streamgage (station 01089500) and forecasted stream stage from the NWS will provide emergency management personnel and residents with information that is critical for flood-response activities, such as evacuations, road closures, disaster declarations, and post-flood recovery. The maps, along with current stream-stage data from the USGS Suncook River streamgage and forecasted stream-stage data from the NWS, can be accessed at the USGS Flood Inundation Mapping Science Web site http://water.usgs.gov/osw/flood_inundation/.

New Hampshire↗