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At least 397 records · Page 22Linked to original sources
USGS2018

Geologic map of the Washington West 30’ × 60’ quadrangle, Maryland, Virginia, and Washington D.C.

The Washington West 30’ × 60’ quadrangle covers an area of approximately 4,884 square kilometers (1,343 square miles) in and west of the Washington, D.C., metropolitan area. The eastern part of the area is highly urbanized, and more rural areas to the west are rapidly being developed. The area lies entirely within the Chesapeake Bay drainage basin and mostly within the Potomac River watershed. It contains part of the Nation's main north-south transportation corridor east of the Blue Ridge Mountains, consisting of Interstate Highway 95, U.S. Highway 1, and railroads, as well as parts of the Capital Beltway and Interstate Highway 66. Extensive Federal land holdings in addition to those in Washington, D.C., include the Marine Corps Development and Education Command at Quantico, Fort Belvoir, Vint Hill Farms Station, the Naval Ordnance Station at Indian Head, the Chesapeake and Ohio Canal National Historic Park, Great Falls Park, and Manassas National Battlefield Park. The quadrangle contains most of Washington, D.C.; part or all of Arlington, Culpeper, Fairfax, Fauquier, Loudoun, Prince William, Rappahannock, and Stafford Counties in northern Virginia; and parts of Charles, Montgomery, and Prince Georges Counties in Maryland. The Washington West quadrangle spans four geologic provinces. From west to east these provinces are the Blue Ridge province, the early Mesozoic Culpeper basin, the Piedmont province, and the Coastal Plain province. There is some overlap in ages of rocks in the Blue Ridge and Piedmont provinces. The Blue Ridge province, which occupies the western part of the quadrangle, contains metamorphic and igneous rocks of Mesoproterozoic to Early Cambrian age. Mesoproterozoic (Grenville-age) rocks are mostly granitic gneisses, although older metaigneous rocks are found as xenoliths. Small areas of Neoproterozoic metasedimentary rocks nonconformably overlie Mesoproterozoic rocks. Neoproterozoic granitic rocks of the Robertson River Igneous Suite intruded the Mesoproterozoic rocks. The Mesoproterozoic rocks are nonconformably overlain by Neoproterozoic metasedimentary rocks of the Fauquier and Lynchburg Groups, which in turn are overlain by metabasalt of the Catoctin Formation. The Catoctin Formation is overlain by Lower Cambrian clastic metasedimentary rocks of the Chilhowee Group. The Piedmont province is exposed in the east-central part of the map area, between overlapping sedimentary units of the Culpeper basin on the west and those of the Coastal Plain province on the east. In this area, the Piedmont province contains Neoproterozoic and lower Paleozoic metamorphosed sedimentary, volcanic, and plutonic rocks. Allochthonous mélange complexes on the western side of the Piedmont are bordered on the east by metavolcanic and metasedimentary rocks of the Chopawamsic Formation, which has been interpreted as part of volcanic arc. The mélange complexes are unconformably overlain by metasedimentary rocks of the Popes Head Formation. The Silurian and Ordovician Quantico Formation is the youngest metasedimentary unit in this part of the Piedmont. Igneous rocks include the Garrisonville Mafic Complex, transported ultramafic and mafic inclusions in mélanges, monzogranite of the Dale City pluton, and Ordovician tonalitic and granitic plutons. Jurassic diabase dikes are the youngest intrusions. The fault boundary between rocks of the Blue Ridge and Piedmont provinces is concealed beneath the Culpeper basin in this area but is exposed farther south. Early Mesozoic rocks of the Culpeper basin unconformably overlie those of the Piedmont and Blue Ridge provinces in the central part of the quadrangle. The north-northeast-trending extensional basin contains Upper Triassic to Lower Jurassic nonmarine sedimentary rocks. Lower Jurassic sedimentary strata are interbedded with basalt flows, and both Upper Triassic and Lower Jurassic strata are intruded by diabase of Early Jurassic age. The Bull Run Mountain fault, a major Mesozoic normal fault characterized by down-to-the-east displacement, separates rocks of the Culpeper basin from those of the Blue Ridge province on the west. On the east, the contact between rocks of the Culpeper basin and those of the Piedmont province is an unconformity, which has been locally disrupted by normal faults. Sediments of the Coastal Plain province unconformably overlie rocks of the Piedmont province along the Fall Zone and occupy the eastern part of the quadrangle. Lower Cretaceous deposits of the Potomac Formation consist of fluvial-deltaic gravels, sands, silts, and clays. Discontinuous fluvial and estuarine terrace deposits of Pleistocene and middle- to late-Tertiary age flank the modern Potomac River valley unconformable capping these Cretaceous strata and the crystalline basement where the Cretaceous has been removed by erosion. East of the Potomac River, the Potomac Formation is onlapped and unconformably overlain by a westward thinning wedge of marine sedimentary deposits of Late Cretaceous and early- and late-Tertiary age. Basement rooted Coastal Plain faults of Tertiary to Quaternary age occur along the Fall Zone and this part of the inner Coastal Plain. These Coastal Plain faults have geomorphic expression that appear to influence river drainage patterns. The geologic map of the Washington West quadrangle is intended to serve as a foundation for applying geologic information to problems involving land use decisions, groundwater availability and quality, earth resources such as natural aggregate for construction, assessment of natural hazards, and engineering and environmental studies for waste disposal sites and construction projects. This 1:100,000-scale map is mainly based on more detailed geologic mapping at a scale of 1:24,000.

Maryland, Virginia↗
USGS1997

Digital data sets that describe aquifer characteristics of the Central Oklahoma Aquifer in central Oklahoma

ARC/INFO export files The data sets in this report include digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Central Oklahoma aquifer in central Oklahoma. This area encompasses all or part of Cleveland, Lincoln, Logan, Oklahoma, Payne, and Pottawatomie Counties. The Central Oklahoma aquifer includes the alluvial and terrace deposits along major streams, the Garber Sandstone and Wellington Formations, and the Chase, Council Grove, and Admire Groups. The Quaternary-age alluvial and terrace deposits consist of unconsolidated clay, silt, sand, and gravel. The Permian-age Garber Sandstone and Wellington Formations consist of sandstone with interbedded siltstone and mudstone. The Permian-age Chase, Council Grove, and Admire Groups consist of sandstone, shale, and thin limestone. The Central Oklahoma aquifer underlies about 3,000 square miles of central Oklahoma where the aquifer is used extensively for municipal, industrial, commercial, and domestic water supplies. Most of the usable ground water within the aquifer is from the Garber Sandstone and Wellington Formations. Substantial quantities of usable ground water also are present in the Chase, Council Grove, and Admire Groups, and in alluvial and terrace deposits associated with the major streams. The aquifer boundaries, hydraulic conductivity and recharge values, and ground-water level elevation contours are from previously published reports.

Oklahoma↗
USGS2016

Potash—A vital agricultural nutrient sourced from geologic deposits

This report summarizes the primary sources of potash in the United States. Potash is an essential nutrient that, along with phosphorus and nitrogen, is used as fertilizer for growing crops. Plants require sufficient potash to activate enzymes, which in turn catalyze chemical reactions important for water uptake and photosynthesis. When potassium is available in quantities necessary for healthy plant growth, disease resistance and physical quality are improved and crop yield and shelf life are increased. Potash is a water-soluble compound of potassium formed by geologic and hydrologic processes. The principal potash sources discussed are the large, stratiform deposits that formed during retreat and evaporation of intracontinental seas. The Paradox, Delaware, Holbrook, Michigan, and Williston sedimentary basins in the United States are examples where extensive potash beds were deposited. Ancient marine-type potash deposits that are close to the surface can be mined using conventional underground mining methods. In situ solution mining can be used where beds are too deep, making underground mining cost-prohibitive, or where underground mines are converted to in situ solution mines. Quaternary brine is another source of potash that is recovered by solar evaporation in manmade ponds. Groundwater from Pleistocene Lake Bonneville (Wendover, Utah) and the present-day Great Salt Lake in Utah are sources of potashbearing brine. Brine from these sources pumped to solar ponds is evaporated and potash concentrated for harvesting, processing, and refinement. Although there is sufficient potash to meet near-term demand, the large marine-type deposits are either geographically restricted to a few areas or are too deep to easily mine. Other regions lack sources of potash brine from groundwater or surface water. Thus, some areas of the world rely heavily on potash imports. Political, economic, and global population pressures may limit the ability of some countries from securing potash resources in the future. In this context, a historical perspective on U.S. potash production in a global framework is discussed.

Open-File Report↗
USGS2021

Geologic and hydrogeologic characteristics of the White River Formation, Lance Formation, and Fox Hills Sandstone, northern greater Denver Basin, southeastern Laramie County, Wyoming

In cooperation with the Wyoming State Engineer’s Office, the U.S. Geological Survey studied the geologic and hydrogeologic characteristics of Cenozoic and Upper Cretaceous strata at a location in southeastern Laramie County within the Wyoming part of the Cheyenne Basin, the northern subbasin of the greater Denver Basin. The study aimed to improve understanding of the aquifers/aquifer systems in these strata, motivated in part by declining groundwater levels and interest in exploring future groundwater supplies. Based on detailed geologic characterization using information obtained by drilling and coring a 960-foot-(ft) deep exploratory borehole, and comparisons with previously published descriptions, identified Cenozoic lithostratigraphic units included 40 ft of Quaternary older alluvial fan deposits consisting of an unconsolidated mixture of sand and gravel with lesser quantities of silt and clay in varying proportions and the underlying 407.3-ft-thick White River Formation of late Eocene-Oligocene age consisting largely of mudrocks with sparse thin beds of sandstone, muddy gravel, and conglomeratic mudrocks. Identified Upper Cretaceous lithostratigraphic units included the 351.6-ft-thick Lance Formation, consisting of terrestrial sedimentary rocks including mudrocks (muddy shale and silty and sandy shale, siltstone, claystone, and mudstone) interbedded with much smaller quantities of very fine- to medium-grained muddy and silty sandstone and coal; the 79.6-ft-thick Fox Hills Sandstone, consisting of a transitional marine sequence of muddy or silty sandstone present in five individual beds; and 86.7 ft of the upper transition member of the Pierre Shale, consisting largely of marine sedimentary rocks such as muddy shale. Beds of the upper and lower Fox Hills Sandstone were separated by tongues of the Lance Formation and upper transition member of the Pierre Shale, respectively. The White River hydrogeologic unit, consisting of the entire White River Formation or Group at the study site, did not contain any substantial secondary permeability features in the mudrocks that composed almost all the unit. A monitoring well (BR–1) was completed in the White River aquifer with the well screen open to the only coarse-grained unit (muddy sandstone) that had sufficient thickness and permeability to be considered as an aquifer. Sampling of the well for a broad suite of constituents indicated groundwater generally was of excellent quality except dissolved arsenic was detected at a concentration greater than the U.S. Environmental Protection Agency (EPA) Maximum Contaminant Level, and dissolved sodium was measured at a concentration greater than several EPA Drinking Water Advisory Levels (DWAs) for the constituent. Well development, well purging for groundwater sampling, and calculated aquifer properties indicated the sandstone aquifer screened by monitoring well BR–1 was not very productive. Analysis of the well water-level responses in BR–1 to atmospheric loading and Earth tides indicated the responses were consistent with a confined-aquifer response with wellbore-storage effects. Hydraulic properties estimated based on these responses yielded values of hydraulic conductivity ( K , 0.057 foot per day [ft/d]), specific storage ( Ss , 1.6×10 −6 per foot [ft −1 ]) and porosity ( n , 0.43). Water levels filtered to remove the effects of atmospheric loading and Earth tides indicated an upward trend (+1.13 foot per year [ft/yr]) during the period analyzed, September 5, 2014, to September 30, 2017. Lithologic characteristics of the Lance hydrogeologic unit, consisting of the entire Lance Formation at the study site, indicated a potential aquifer in a “sandy” interval in the upper part of the unit. Most of the Lance hydrogeologic unit below the “sandy” interval consisted of various low-permeability lithologies unlikely to yield substantial quantities of water. This lower part of the hydrogeologic unit likely functions as a confining unit separating the underlying Lance-Fox Hills aquifer. A geologic cross section constructed for this study indicated fine-grained sediments composed most of the Lance Formation/hydrogeologic unit not only at the study location, but also throughout southern Laramie County along the line of section and throughout the Wyoming and Colorado parts of the Cheyenne Basin. A monitoring well (LN–1) completed in a sandstone bed in the “sandy” interval of the Lance hydrogeologic unit produced a mean of about 23 gallons per minute (gal/min) during well development, indicating sandstone beds can form moderately productive confined subaquifers in this part of the hydrogeologic unit. Analysis of the well water-level responses in well LN–1 to atmospheric loading and Earth tides indicated the responses were consistent with a confined-aquifer response. Hydraulic properties estimated based on these responses yielded values for a lower bounding K of 0.60 ft/d, Ss of 1.6×10 −6 ft −1 , and n of 0.38. Water levels filtered to remove the effects of atmospheric loading and Earth tides indicated a downward trend (−0.86 ft/yr) during the period analyzed (November 8, 2014, to September 30, 2017). Analyses for a broad suite of constituents in samples from well LN–1 indicated groundwater quality generally was excellent, although dissolved sodium was measured at a concentration greater than two EPA DWA levels for the constituent. Because of the absence of any overlying or intertonguing sandstone beds belonging to the lower/basal part of the Lance Formation, the Lance-Fox Hills aquifer at the study site consisted only of the five sandstone beds of the Fox Hills Sandstone. The cross section constructed for this study illustrated how the Fox Hills Sandstone, and thus, most of the Lance-Fox Hills aquifer, consists of a series of sandstone bodies that overlap (shingle) upward to the east across southern Laramie County. These bodies collectively form a fairly continuous body of sandstone, thus potentially forming an areally extensive aquifer across southern Laramie County, and by extension, throughout most of the formation’s extent in the Wyoming part of the Cheyenne Basin, as is the case in the Colorado part of the basin. A monitoring well (FH–1) completed in part of the thickest sandstone bed of the Lance-Fox Hills aquifer was moderately to highly productive and easily produced 25 to 30 gal/min after development. Substantially larger water production rates likely could be obtained by penetrating the full thickness of this bed and by completing a well open to the other overlying and underlying sandstone beds of the aquifer. Analysis of the water-level responses in well FH–1 to atmospheric loading and Earth tides indicated the responses were consistent with a confined-aquifer response. Hydraulic properties computed based on these responses yielded values for a lower bounding estimate for K of 0.26 ft/d, for Ss of 1.0×10 −6 ft −1 , and for n of 0.41. Water levels filtered to remove the effects of atmospheric loading and Earth tides indicated a downward trend (−1.74 ft/yr) during the period analyzed, December 19, 2014, to September 30, 2017. Sampling of monitoring well FH–1 and two production wells completed in the Fox Hills Sandstone in other parts of Laramie County indicated groundwater quality generally is excellent, although pH exceeded a recommended EPA aesthetic drinking-water standard (Secondary Maximum Contaminant Level) in two of three sampled wells, total dissolved solids concentrations exceeded the Secondary Maximum Contaminant Level in one of the two sampled production wells, and dissolved sodium was measured in all three sampled wells at a concentration greater than two EPA DWA levels for the constituent. The Wyoming Class II agricultural (irrigation) sodium adsorption ratio standard of 8 was exceeded in all three sampled wells, indicating these waters are not suitable for irrigation use. Computed vertical hydraulic gradients indicated a strong potential for downward flow throughout the groundwater system at the study site, including from the low-yielding aquifer in the upper White River Formation/hydrogeologic unit (monitoring well BR–1) to the sandstone subaquifer in the Lance Formation/hydrogeologic unit (monitoring well LN–1), and from the Lance subaquifer (monitoring well LN–1) to the sandstone bed/aquifer that composes much of the Lance-Fox Hills aquifer thickness at the study site (monitoring well FH–1). However, large hydraulic-head differences between wells indicated high resistance to vertical flow attributable to the low vertical hydraulic conductivity of intervening strata, which consisted almost entirely of low-permeability mudrocks. The confined nature of the sandstone aquifers monitored by the various wells coupled with dissimilarities between groundwater-level fluctuations and trends in groundwater levels indicated downward flow through the intervening strata (primarily mudrocks in the various lithostratigraphic/hydrogeologic units) between the examined sets of wells likely was small.

Wyoming↗
USGS1978

Mercury analysis of sediments from cores in Clear Lake, Lake County, California

Cores of late Quaternary sediments were collected from several sites in Clear Lake (fig. 1). Samples from two of these cores (fig. 2, 3) have been analyzed for their mercury content as part of a study on the time of emplacement of the mercury ore body at the nearby Sulphur Bank mine (fig. 1). The samples were analyzed in laboratories of the U.S. Geological Survey by the mercury vapor detector method (Vaughn and McCarthy, 1964; Vaughn, 1967). The analyses of core 6, except samples 332, 341, 343, 386, 406, and 462, were done by Mr. Kam Leong (Table 1); the remaining analyses were done by Mr. Allen Meier. Analyses of core 10 (table 2) were done by Mr. Meier. Meier reported interference by organic material in the samples he analyzed. Because the two sets of data are not in agreement, most of the samples submitted to Leong and Meier are being reanalyzed.

California↗
USGS1998

Quaternary geology and liquefaction susceptibility, Napa, California 1:100,000 quadrangle: A digital database

Earthquake-induced ground failures such as liquefaction have historically brought loss of life and damage to property and infrastructure. Observations of the effects of historical large-magnitude earthquakes show that the distribution of liquefaction phenomena is not random. Liquefaction is restricted to areas underlain by loose, cohesionless sands and silts that are saturated with water. These areas can be delineated on the basis of thorough geologic, geomorphic, and hydrologic mapping and map analysis (Tinsley and Holzer, 1990; Youd and Perkins, 1987). Once potential liquefaction zones are delineated, appropriate public and private agencies can prepare for and mitigate seismic hazard in these zones. In this study, we create a liquefaction susceptibility map of the Napa 1:100,000 quadrangle using Quaternary geologic mapping, analysis of historical liquefaction information, groundwater data, and data from other studies. The study is atterned after state-of-the-art studies by Youd (1973) Dupre and Tinsley (1980) and Dupre (1990) in the Monterey-Santa Cruz area, Tinsley and others (1985) in the Los Angeles area, and Youd and Perkins (1987) in San Mateo County, California. The study area comprises the northern San Francisco Metropolitan Area, including the cities of Santa Rosa, Vallejo, Napa, Novato, Martinez, and Fairfield (Figure 1). Holocene estuarine deposits, Holocene stream deposits, eolian sands, and artificial fill are widely present in the region (Helley and Lajoie, 1979) and are the geologic materials of greatest concern. Six major faults capable of producing large earthquakes cross the study area, including the San Andreas, Rodgers Creek, Hayward, West Napa, Concord, and Green Valley faults (Figure 1).

California↗
USGS1994

User's guide to revised method-of-characteristics solute-transport model (MOC--version 31)

The U.S. Geological Survey computer model to simulate two-dimensional solute transport and dispersion in ground water (Konikow and Bredehoeft, 1978; Goode and Konikow, 1989) has been modified to improve management of input and output data and to provide progressive run-time information. All opening and closing of files are now done automatically by the program. Names of input data files are entered either interactively or using a batch-mode script file. Names of output files, created automatically by the program, are based on the name of the input file. In the interactive mode, messages are written to the screen during execution to allow the user to monitor the status and progress of the simulation and to anticipate total running time. Information reported and updated during a simulation include the current pumping period and time step, number of particle moves, and percentage completion of the current time step. The batch mode enables a user to run a series of simulations consecutively, without additional control. A report of the model's activity in the batch mode is written to a separate output file, allowing later review. The user has several options for creating separate output files for different types of data. The formats are compatible with many commercially available applications, which facilitates graphical postprocessing of model results. Geohydrology and Evaluation of Stream-Aquifer Relations in the Apalachicola-Chattahoochee-Flint River Basin, Southeastern Alabama, Northwestern Florida, and Southwestern Georgia By Lynn J. Torak, Gary S. Davis, George A. Strain, and Jennifer G. Herndon Abstract The lower Apalachieola-Chattahoochec-Flint River Basin is underlain by Coastal Plain sediments of pre-Cretaceous to Quaternary age consisting of alternating units of sand, clay, sandstone, dolomite, and limestone that gradually thicken and dip gently to the southeast. The stream-aquifer system consism of carbonate (limestone and dolomite) and elastic sediments, which define the Upper Floridan aquifer and Intermediate system, in hydraulic connection with the principal rivers of the basin and other surface-water features, natural and man made. Separate digital models of the Upper Flori-dan aquifer and Intermediate system were constructed by using the U.S. Geological Survey's MODular Finite-Element model of two dimensional ground-water flow, based on concep- tualizations of the stream-aquifer system, and calibrated to drought conditions of October 1986. Sensitivity analyses performed on the models indicated that aquifer hydraulic conductivity, lateral and vertical boundary flows, and pumpage have a strong influence on groundwater levels. Simulated pumpage increases in the Upper Floridan aquifer, primarily in the Dougherty Plain physiographic district of Georgia,. caused significant reductions in aquifer discharge to streams that eventually flow to Lake Seminole and the Apalachicola River and Bay. Simulated pumpage increases greater than 3 times the October 1986 rates caused drying ofsome stream reaches and parts of the Upper Floridan aquifer in Georgia. Water budgets prepared from simulation results indicate that ground- water discharge to streams and recharge by horizontal and vertical flow are the principal mechanisms for moving water through the flow system. The potential for changes in ground-water quality is high in areas where chemical constituents can be mobilized by these mechanisms. Less than 2 percent of ground-water discharge to streams comes from the Intermediate system; thus, it plays a minor role in the hydrodynamics of the stream- aquifer system.

Water-Resources Investigations Report↗
USGS2003

Structure of the Tucson Basin, Arizona from gravity and aeromagnetic data

Interpretation of gravity and high-resolution aeromagnetic data reveal the three-dimensional geometry of the Tuscson Basin, Arizona and the lithology of its basement. Limited drill hole and seismic data indicate that the maximum depth to the crystalline basement is approximately 3600 meters and that the sedimentary sequences in the upper ~2000 m of the basin were deposited during the most recent extensional episode that commenced about 13 Ma. The negative density contrasts between these upper Neogene and Quaternary sedimentary sequences and the adjacent country rock produce a Bouguer residual gravity low, whose steep gradients clearly define the lateral extent of the upper ~2000m of the basin. The aeromagnetic maps show large positive anomalies associated with deeply buried, late Cretaceous-early Tertiary and mid-Tertiary igneous rocks at and below the surface of the basin. These magnetic anomalies provide insight into the older (>13 Ma) and deeper structures of the basin. Simultaneous 2.5-dimensional modeling of both gravity and magnetic anomalies constrained by geologic and seismic data delineates the thickness of the basin and the dips of the buried faults that bound the basin. This geologic-based forward modeling approach to using geophysical data is shown to result in more information about the geologic and tectonic history of the basin as well as more accurate depth to basement determinations than using generalized geophysical inversion techniques.

Open-File Report↗
USGS2020

Geologic map of the Paeroa Fault block and surrounding area, Taupo Volcanic Zone, New Zealand

The Taupo Volcanic Zone (TVZ), New Zealand, is the most productive area of explosive silicic volcanism in the world. Faulted early and middle Pleistocene volcanic products are generally concealed beneath voluminous, generally unfaulted, younger volcanic products. An exception is the southeast margin of the TVZ where the two parallel, northeast-trending Paeroa and Te Weta Fault blocks expose Quaternary volcanic products consisting predominantly of caldera-related, rhyolitic ignimbrites and lacustrine sediments. The Taupo-Reporoa Basin is situated along the eastern part of the map area, and its northernmost part underwent collapse to form Reporoa Caldera. The Paeroa Fault block is the largest exposed fault block within the TVZ, and it encompasses early and middle Pleistocene ignimbrites and sedimentary deposits that are buried throughout the Taupo-Reporoa Basin to the east. This map displays the volcanic and sedimentary geology of ~430 km 2 of the Paeroa Fault block and the adjacent Te Weta Fault block at a scale of 1:50,000. Volcanic and sedimentary rocks are divided into the Reporoa Group, Whakamaru Group, and Huka Group (from oldest to youngest), which are overlain by relatively unfaulted late Pleistocene and Holocene surficial volcanic and sedimentary deposits.

Open-File Report↗
USGS1999

Preliminary geologic map of the San Guillermo Mountain Quadrangle, Ventura County, California

New 1:24,000-scale geologic mapping in the Cuyama 30' x 60' quadrangle, in support of the USGS Southern California Areal Mapping Project (SCAMP), is contributing to a more complete understanding of the stratigraphy, structure, and tectonic evolution of the complex junction area between the NW-striking Coast Ranges and EW-striking western Transverse Ranges. The 1:24,000-scale geologic map of the San Guillermo Mountain quadrangle is one of six contiguous 7 1/2' quadrangle geologic maps in the eastern part of the Cuyama map area being compiled for a more detailed portrayal and reevaluation of geologic structures and rock units shown on previous geologic maps of the area (e.g., Dibblee, 1979). The following observations and interpretations are based on the new San Guillermo Mountain geologic compilation: (1) The new geologic mapping in the northern part of the San Guillermo Mountain quadrangle allows for reinterpretation of fault architecture that bears on potential seismic hazards of the region. Previous mapping had depicted the eastern Big Pine fault (BPF) as a northeast-striking, sinistral strike-slip fault that extends for 30 km northeast of the Cuyama River to its intersection with the San Andreas fault (SAF). In contrast the new mapping indicates that the eastern BPF is a thrust fault that curves from a northeast strike to an east strike, where it is continuous with the San Guillermo thrust fault, and dies out further east about 15 km south of the SAF. This redefined segment of the BPF is a south-dipping, north-directed thrust, with dominantly dip slip components (rakes > 60 deg.), that places Middle Eocene marine rocks (Juncal and Matilija Formations) over Miocene through Pliocene(?) nonmarine rocks (Caliente, Quatal, and Morales Formations). Although a broad northeast-striking fault zone, exhibiting predominantly sinistral components of slip (rakes < 45 deg.), extends to the SAF as previously mapped, the fault zone does not connect to the southwest with the BPF but instead curves into a southwest-directed thrust fault system a short distance north of the BPF. Oligocene to Pliocene(?) nonmarine sedimentary and volcanic rocks of the Plush Ranch, Caliente, and Morales(?) Formations are folded on both sides of this fault zone (informally named the Lockwood Valley fault zone [LVFZ] on the map). South-southeast of the LVFZ overturned folds have southward vergence. Several moderate-displacement (< 50 m), mainly northwest-dipping thrust and reverse faults, exhibiting mostly sinistral-oblique slip, flank and strike parallel to the overturned folds. The fold vergence and thrust direction associated with the LVFZ is opposite to that of the redefined BPF, providing further evidence that the two faults are distinct structures. These revised fault interpretations bring into question earlier estimates of net sinistral strike-slip displacement of as much as 13 km along the originally defined eastern BPF, which assumed structural connection with the LVFZ. Also, despite sparse evidence for repeated Quaternary movement on the LVFZ (e.g., Dibblee, 1982), the potential for a large earthquake involving coseismic slip on both the LVFZ and the central BPF to the southwest may not be as great as once believed. (2) Several generations of Pleistocene and younger dissected alluvial terrace and fan deposits sit at various levels above modern stream channels throughout the quadrangle. These deposits give testimony to the recent uplift and related fault deformation that has occurred in the area. (3) A vast terrane of Eocene marine sedimentary rocks (Juncal and Matilija Formations and Cozy Dell Shale) exposed south of the Big Pine fault forms the southern two-thirds of the San Guillermo Mountain quadrangle. Benthic foraminifers collected from various shale intervals within the Juncal Formation indicate a Middle Eocene age (Ulatisian) for the entire formation (K. McDougall, unpub. data, 1998) and deposition at paleodepths as great as 2,000 m (i.e., lowe

California↗
USGS2017

Last interglacial climates

The last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial unit MIS 5d. The age of the stage is determined by correlation to uranium-thorium dates of raised coral reefs. The most detailed proxy record of interglacial climate is found in the Vostok ice core where the temperature reached current levels 132,000 yr ago and continued rising for another two millennia. Approximately 127,000 yr ago the Eemian mixed forests were established in Europe. They developed through a characteristic succession of tree species, probably surviving well into the early glacial stage in southern parts of Europe. After ca. 115,000 yr ago, open vegetation replaced forests in northwestern Europe and the proportion of conifers increased significantly farther south. Air temperature at Vostok dropped sharply. Pulses of cold water affected the northern North Atlantic already in late MIS 5e, but the central North Atlantic remained warm throughout most of MIS 5d. Model results show that the sea surface in the eastern tropical Pacific warmed when the ice grew and sea level dropped. The essentially interglacial conditions in southwestern Europe remained unaffected by ice buildup until late MIS 5d when the forests disappeared abruptly and cold water invaded the central North Atlantic ca. 107,000 yr ago. ?? 2002 University of Washington.

Quaternary Research↗
USGS2018

Cenozoic geology of Fort Irwin and vicinity, California

The geology of the Fort Irwin National Training Center in the north-central Mojave Desert, California, provides insights into the hydrology and water resources of the area. The Fort Irwin area is underlain by rocks ranging in age from Proterozoic to Quaternary that have been deformed by faults as young as Quaternary. Pre-Tertiary sedimentary, igneous, and metamorphic bedrock and Miocene volcanic and sedimentary rocks are exposed in the mountains and ridges, between which are basins containing Quaternary to Pliocene deposits. During the Miocene, in the western part of Fort Irwin, development of the Eagle Crags volcanic field resulted in a complex assemblage of lava flows, pyroclastic flow and fallout tephra deposits, and volcaniclastic sedimentary rocks that were deposited in alluvial, fluvial, and locally lacustrine environments; in the eastern part of Fort Irwin, epiclastic sedimentary rocks and minor tuffaceous rocks were deposited in alluvial, fluvial, and locally lacustrine environments. In the Pliocene and Quaternary, sandstone and conglomerate were deposited in alluvial and fluvial environments, and locally fine-grained materials were deposited in lacustrine, eolian, playa, and groundwater discharge environments. The Fort Irwin area is transected by Neogene to Holocene northwest- and east-striking (and fewer northeast-striking) strike-slip, normal, and locally thrust faults. Structural blocks between faults are broadly warped, and locally rocks adjacent to the faults are folded and sheared. Many of these faults influenced the formation or modification of basins, especially after about 11 million years, when the Eastern California Shear Zone developed in this area. The three-dimensional geologic framework produced by the late Cenozoic stratigraphic and structural history is represented by the continuity or spatial limitations of lithostratigraphic and correlative hydrogeologic properties. The continuity or limitations of rocks and properties influence how water moved (and moves) through the hydrogeologic system.

California↗
USGS1983

Hydrology of area 54, northern Great Plains, and Rocky Mountain coal provinces, Colorado and Wyoming

A nationwide need for information characterizing hydrologic conditions in mined and potential mine areas has become paramount with the enactment of the Surface Mining Control and Reclamation Act of 1977. This report, one in a series covering the coal provinces nationwide, presents information thematically by describing single hydrologic topics through the use of brief texts and accompanying maps, graphs, or other illustrations. The summation of the topical discussions provides a description of the hydrology of the area. Area 54, in north-central Colorado and south-central Wyoming, is 1 of 20 hydrologic reporting areas of the Northern Great Plains and Rocky Mountain coal provinces. Part of the Southern Rocky Mountains and Wyoming Basin physiographic provinces, the 8,380-square-mile area is one of contrasting geology, topography, and climate. This results in contrasting hydrologic characteristics. The major streams, the North Platte, Laramie, and Medicine Bow Rivers, and their principal tributaries, all head in granitic mountains and flow into and through sedimentary basins between the mountain ranges. Relief averages 2,000 to 3,000 feet. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, which produces deep snowpacks. Snowmelt in spring and summer provides most streamflow. Precipitation in the basins averages 10 to 16 inches annually, insufficient for sustained streamflow; thus, streams originating in the basins are ephemeral. Streamflow quality is best in the mountains where dissolved-solids concentrations generally are least. These concentrations increase as streams flow through sedimentary basins. The increases are mainly natural, but some may be due to irrigation in and adjacent to the flood plains. In the North Platte River, dissolved-solids concentrations are usually less than 300 milligrams per liter; in the Laramie and the Medicine Bow Rivers, the concentrations may average 500 to 850 milligrams per liter. However, water-quality stations on the Laramie and the Medicine Bow Rivers are farther removed from the mountain sources than the stations in the North Platte drainage. Because of the semiarid climate of the basins, soils are not adequately leached. Consequently, flow in ephemeral streams usually has a larger concentration of dissolved solids than that in perennial streams, averaging 1,000 to 1,600 milligrams per liter. Aquifers containing usable ground water are combined into three groups: (1) consolidated and unconsolidated non-coal-bearing Quaternary and Upper Tertiary deposits, (2) Mesozoic and Paleozoic sedimentary rocks, and (3) Lower Tertiary and Upper Cretaceous sedimentary rocks containing coal. These aquifers are used for municipal, domestic, irrigation, and stock supplies. Well yields range from about 5 to 1,000 gallons per minute, and depend on type of aquifer, saturated thickness, and degree of fracturing. The best quality ground water usually comes from the non-coal-bearing Quaternary and Upper Tertiary rocks or the Mesozoic and Paleozoic rocks; often it is dominated by calcium and bicarbonate ions. The coal-bearing formations have a large variability in water chemistry; dominant ions may be bicarbonate or sulfate and sodium, calcium, or magnesium. Dissolved-solids concentrations are generally larger than in the former two groups. The U.S. Geological Survey operates a network of hydrologic stations to observe the streamflow and groundwater conditions. This network currently includes 31 surface-water stations and 35 observation wells; information is available for many other sites observed in the past. Data available include rate of flow, water levels, and water quality; much of the data are available in published reports or from computer storage through the National Water Data Exchange (NAWDEX) or the National Water Data Storage and Retrieval System (WATSTORE). Five formations of Late Cretaceous and early Tertiary age contain coal.

Colorado, Wyoming↗
USGS2009

Water-Level Data for the Albuquerque Basin and Adjacent Areas, Central New Mexico, Period of Record Through September 30, 2008

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin are currently (2008) obtained soley from ground-water resources. An increase of about 20 percent in the population from 1990 to 2000 also resulted in an increased demand for water. A network of wells was established to monitor changes in ground-water levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2008), the network consists of 144 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 125 sites through water-year 2008. In addition, data from 19 wells (Sites 127-30, 132-134, 136, 138-142 and 144-149) owned, maintained, and measured by Sandia National Laboratories are presented in this report.

Open-File Report↗
USGS2006

Water-Level Data for the Albuquerque Basin and Adjacent Areas, Central New Mexico, Period of Record Through 2004

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the Albuquerque Basin are obtained solely from ground-water resources. An increase of approximately 20 percent in the population from 1991 to present also resulted in an increased demand for water. From April 1982 through September 1983, a network of wells was established to monitor changes in ground-water levels throughout the Albuquerque Basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. Currently (2004), the network consists of 234 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 155 sites through 2004. Water-level and other data for 71 sites are collected by other agencies. Water-level data for 8 sites of the 155 sites measured by the U.S. Geological Survey were not available for this report.

Open-File Report↗
USGS2014

Glacial and Quaternary geology of the northern Yellowstone area, Montana and Wyoming

This field guide focuses on the glacial geology and paleoecology beginning in the Paradise Valley and progressing southward into northern Yellowstone National Park. During the last (Pinedale) glaciation, the northern Yellowstone outlet glacier flowed out of Yellowstone Park and down the Yellowstone River Valley into the Paradise Valley. The field trip will traverse the following Pinedale glacial sequence: (1) deposition of the Eightmile terminal moraines and outwash 16.5 ± 1.4 10Be ka in the Paradise Valley; (2) glacial recession of ~8 km and deposition of the Chico moraines and outwash 16.1 ± 1.7 10Be ka; (3) glacial recession of 45 km to near the northern Yellowstone boundary and moraine deposition during the Deckard Flats readjustment 14.2 ± 1.2 10Be ka; and (4) glacial recession of ~37 km and deposition of the Junction Butte moraines 15.2 ± 1.3 10Be ka (this age is a little too old based on the stratigraphic sequence). Yellowstone's northern range of sagebrush-grasslands and bison, elk, wolf, and bear inhabitants is founded on glacial moraines, sub-glacial till, and outwash deposited during the last glaciation. Floods released from glacially dammed lakes and a landslide-dammed lake punctuate this record. The glacial geologic reconstruction was evaluated by calculation of basal shear stress, and yielded the following values for flow pattern in plan view: strongly converging—1.21 ± 0.12 bars (n = 15); nearly uniform—1.04 ± 0.16 bars (n = 11); and strongly diverging—0.84 ± 0.14 bars (n = 16). Reconstructed mass balance yielded accumulation and ablation each of ~3 km3/yr, with glacial movement near the equilibrium line altitude dominated by basal sliding. Pollen and charcoal records from three lakes in northern Yellowstone provide information on the postglacial vegetation and fire history. Following glacial retreat, sparsely vegetated landscapes were colonized first by spruce parkland and then by closed subalpine forests. Regional fire activity increased significantly with the development of closed subalpine forests as a result of increased fuel biomass and warmer summers. Warm dry conditions prevailed at low elevations during the early Holocene, as indicated by the presence of steppe and open mixed conifer forest. At the same time, closed subalpine forests with low fire frequency were present at higher elevations, suggesting relatively wet summer conditions. Douglas fir populations expanded throughout northern Yellowstone in the middle Holocene as a result of effectively drier conditions than before, and a decline of mesophytic plant taxa during the late Holocene imply continued drying, even though fire frequency decreased in recent millennia.

Montana;Wyoming↗
USGS1980

Quaternary stratigraphic sections with radiocarbon dates, Wiseman Quadrangle, Alaska

The Wiseman quadrangle contains a rich stratigraphic record of alluvial, glacial, and periglacial events of the late Quaternary in the south-central Brooks Range. The numerous bluffs along the Koyukuk River and its tributaries expose drift sheets of the late Pleistocene Itkillik I glacial phase (table 1), and outwash and other proglacial deposits of the succeeding Itkillik II phase. During Itkillik I time, glaciers flowed south through virtually all of the valleys of the south-central Brooks Range to terminate in piedmont lobes within the Koyukuk lowland (Hamilton, 1978, 1979a). Outwash covered the Koyukuk Valley floor beyond the ice limits. Glaciers of Itkillik II age were more restricted; the largest reached positions near the south margin of the range, but many mountain valleys of the Wiseman quadrangle remained unglaciated. Lower alluvial terraces of Holocene age record alternating episodes of aggradation and soil development. Some of these events were controlled locally by mass movements and perhaps by faulting, but others may be related to regional climatic reversals and to fluctuations of cirque glaciers at valley heads.

Alaska↗
USGS1980

Ground-water conditions at Beale Air Force Base and vicinity, California

Ground-water conditions were studied in a 168-square-mile area between the Sierra Nevada and the Feather River in Yuba County, Calif. The area is in the eastern part of the Sacramento Valley and includes most of Beale Air Force Base. Source, occurrence, movement, and chemical quality of the ground water were evaluated. Ground water occurs in sedimentary and volcanic rocks of Tertiary and Quaternary age. The base of the freshwater is in the undifferentiated sedimentary rocks of Oligocene and Eocene age, that contain water of high dissolved-solids concentration. The ground water occurs under unconfined and partly confined conditions. At Beale Air Force Base it is at times partly confined. Recharge is principally from the rivers. Pumpage in the study area was estimated to be 129,000 acre-feet in 1975. In the 1960's, water levels in most parts of the study area declined less rapidly than in earlier years or became fairly stable. In the 1970's, water levels at Beale Air Force Base declined only slightly. Spacing of wells on the base and rates of pumping are such that excessive pumping interference is avoided. Water quality at the base and throughout the study area is generally good. Dissolved-solids concentrations are 700 to 900 milligrams per liter in the undifferentiated sedimentary rocks beneath the base well field. (USGS)

Open-File Report↗