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At least 1,117 records · Page 62Linked to original sources
USGS1999

Ground-water levels and flow directions in the glacial sediments and the Lockport Dolomite in southeastern Darke and northeastern Preble counties, Ohio, July 1998

During the summer of 1997, the U.S. Environmental Protection Agency (USEPA) began an emergency removal action at the Lewisburg Drum Site in northern Preble County, Ohio. The site is about 3 miles west-northwest of the village of Lewisburg. The USEPA removed about 1,200 drums of waste ink from the site, as well as 2,500 cubic yards of contaminated soil and 100,000 gallons of ground water. Because of the potential for off-site migration of ground-water contamination, USEPA sampled residential wells in the area; results from the samples collected by USEPA indicated that the quality of water in some privately owned wells may have been affected by contaminants from the site. However, the directions of ground-water flow in the area were not known. In 1998, the U.S. Geological Survey (USGS), in cooperation with the USEPA, measure water levels in the vicinity of the site. This map will aid in the interpretation of the water-quality data collected by USEPA.

Ohio↗
USGS1986

Geology of the platanares geothermal area, Departamento de Copan, Honduras

Platanares is located 16 km west of Santa Rosa de Copan, Honduras, along the Quebrada del Agua Caliente. The thermal manifestations are along faults in tuffs, tuffaceous sedimentary rocks, and lavas of the Padre Miguel Group. These tuffs are silicified near the faults, are fractured, and may provide the fracture permeability necessary for the hydrothermal system. Tuffs are overlain by a wedge of terrace gravels up to 60 m thick. Quaternary conglomerates of the Quebrada del Agua Caliente are cemented by silica sinter. The Platanares area contains numerous faults, all of which appear to be extensional. There are four groups of faults (N80/sup 0/E to N70/sup 0/W, N30/sup 0/ to 60/sup 0/W, N40/sup 0/ to 65/sup 0/E, and N00/sup 0/ to 05/sup 0/W). All hot springs at this site are located along faults that trend mostly northwest and north. Twenty-eight spring groups were described over an area of 0.2 km/sup 2/; half were boiling. Based on surface temperatures and flow rates, between 0.7 and 1.0 MW thermal energy is estimated for the area. The increased temperature of the stream flowing through the thermal area indicates that several megawatts of thermal energy are being added to the stream. We recommend that a dipole-dipole resistivity line be run along the Quebrada del Agua Caliente to identify zones of fracture permeability associated with buried faults and hot water reservoirs within those fault zones. A thermal gradient corehole should be drilled at Platanares to test temperatures, lithologies, and permeability of the hydrothermal system.

Journal of Volcanology and Geothermal Research↗
USGS1987

Construction, geologic, and hydrologic data for observation wells in the Reelfoot Lake area, Tennessee and Kentucky

Twenty-three observation wells were installed at 12 sites in the Reelfoot Lake area of Kentucky and Tennessee during July 1986. The wells were installed to supplement an existing water level network and to provide additional data on the hydraulic characteristics and vertical hydraulic gradients in the alluvial aquifer near Reelfoot Lake. Well yields ranged from less than 20 gallons per minute to about 140 gallons per minute. The specific capacities of the wells ranged from less than 1 to 17.1 gallons per minute per foot of drawdown. Three stratigraphic sequences were encountered during drilling. Clay and silty clay was about 40 feet deep near the southwest corner of Reelfoot Lake. Predominantly medium- to coarse grained sand occurred below about 15 feet of silt and clay near the west and northwest sides of Reelfoot Lake. Along the western limit of the study area, near Lake No. 9 and the Mississippi River, about 20 to 30 feet of silt and silty sand occurred below land surface.

Kentucky, Tennessee↗
USGS1964

Geology and ground-water resources of Nobles County, and part of Jackson County, Minnesota

The area described in this report is in southwestern Minnesota, about 130 miles southwest of Minneapolis and St. Paul. It includes; Nobles County and the western tier of townships in Jackson County, a total of 864 square miles. Worthington, the Nobles County seat, is the largest city in the area, having a population of 9,015 persons (1960 census). Farming is the leading occupation, and food processing is the major industry. Critical water shortages have occurred in several parts of the area. The climate is characterized by mild, subhumid summers and relatively long, severe winters. Mean monthly temperatures range from 15.1 °F in January to 73.3 °F in July. The mean annual precipitation is 26.75 inches. The crest of the Coteau des Prairies, a broad highland belt, traverses Nobles County from northwest to southeast. Three glacial end moraines and their associated ground moraines trend south to southeast across the area. Altitudes range from about 1,820 feet on the crest of the coteau in the northwestern part of the area to about 1,390 feet above mean sea level in the Jack and Okabena Creek valleys in the northeast. The Mississippi-Missouri River drainage divide crosses the area from north to east. The Gary outer end moraine trends southeast through central Nobles County. East of this moraine the land is poorly drained and contains numerous lakes and swamps; west of this moraine the land is well drained and contains few, if any, undrained depressions. Within the area, granite and Sioux Quartzite of Precambrian age are overlain by Cretaceous strata, except locally in the northeast and northwest parts of the area where the quartzite is directly overlain by glacial drift. The Cretaceous strata are composed of interbedded shale, siltstone, and sandstone. The surface of the area is composed of Pleistocene deposits of glacial drift and some thin, patchy deposits of Recent age. Bedrock is not known to crop out in the area. The drift ranges in thickness from about 150 feet in the southwest and northeast corners to about 500 feet on the highest part of the Coteau des Prairies. The Precambrian granite is not a source of ground water in this area. The Sioux Quartzite yields moderate supplies in adjacent counties to the north and west, but because of its sporadic occurrence it does not constitute an important water source in this area. The Cretaceous sandstone units are a secondary source of ground water and yield adequate supplies 'to at least 24 farm wells, which range in depth from 283 to 586 feet below land surface. The primary source of ground water in the Nobles-Jackson County area is the glacial drift. Buried outwash deposits supply water to 7 of the 10 municipalities and to most of the farms in the area. Two Worthington city wells, completed in a buried outwash deposit underlying East Okabena dry lake bed, were tested for short periods at 500 gallons per minute. The estimated coefficient of transmissibility for the aquifer at one of the wells was 70,000 gpd (gallons per day) per ft. The buried outwash deposits may occur anywhere within the drift from about 15 feet below land surface to bedrock which is as much as 500 feet below land surface. The outwash ranges from a fraction of a foot to more than 25 feet in thickness where permeable; below the water table it generally will supply ample quantities of water to properly constructed wells. Surflcial outwash deposits fill the valley bottoms and form the terrace deposits associated with the present-day drainage channels. The thicker, more extensive, and continuous deposits occur in the proglacial stream channels that drained the fronts of the ice sheets rather than in those channels that now drain the backs of the moraines. The surflcial outwash deposits generally are made up of sand, gravel and some silt and clay, and range in thickness from 0 to more than 60 feet; they range in width from a few feet in the narrow tributaries to about one mile in the larger stream valleys. Four municipalities and many farms obtain part or all of their water supplies from surficial outwash. An Adrian municipal well, completed in this source, was pumped at a rate of 400 gpm. At the confluence of two streams which drain Ocheda Lake in southeastern Nobles County, the sand and gravel section is more than 60 feet thick in places. Results of a pumping test here showed an average coefficient of transmissibility of 150,000 gpd per ft. Coefficients of transmissibility may be as much as 500,000 gdp per ft in the thickest part of the deposit if the permeability of the sand and gravel is uniform. Recharge to the surflcial outwash deposits is relatively rapid; it is slower to the buried outwash deposits where the descending water must percolate through till of low permeability before entering the aquifers. The quality of water in the Precambrian crystalline rocks, the Cretaceous strata, and the buried Pleistocene aquifers is poor. Chemical analyses of 22 water samples showed that dissolved solids ranged from 1,100 ppm (parts per million) to 3,050 ppm. Water from the surficial outwash deposits is good by comparison; dissolved solids in water from these aquifers ranged from 425 to 870 ppm.

Minnesota↗
USGS2012

Preliminary geologic map of the Big Costilla Peak area, Taos County, New Mexico, and Costilla County, Colorado

This map covers the Big Costilla Peak, New Mex.‒Colo. quadrangle and adjacent parts of three other 7.5 minute quadrangles: Amalia, New Mex.‒Colo., Latir Peak, New Mex., and Comanche Point, New Mex. The study area is in the southwesternmost part of that segment of the Sangre de Cristo Mountains known as the Culebra Range; the Taos Range segment lies to the southwest of Costilla Creek and its tributary, Comanche Creek. The map area extends over all but the northernmost part of the Big Costilla horst, a late Cenozoic uplift of Proterozoic (1.7-Ga and less than 1.4-Ga) rocks that is largely surrounded by down-faulted middle to late Cenozoic (about 40 Ma to about 1 Ma) rocks exposed at significantly lower elevations. This horst is bounded on the northwest side by the San Pedro horst and Culebra graben, on the northeast and east sides by the Devils Park graben, and on the southwest side by the (about 30 Ma to about 25 Ma) Latir volcanic field. The area of this volcanic field, at the north end of the Taos Range, has undergone significantly greater extension than the area to the north of Costilla Creek. The horsts and grabens discussed above are all peripheral structures on the eastern flank of the San Luis basin, which is the axial part of the (about 26 Ma to present) Rio Grande rift at the latitude of the map. The Raton Basin lies to the east of the Culebra segment of the Sangre de Cristo Mountains. This foreland basin formed during, and is related to, the original uplift of the Sangre de Cristo Mountains which was driven by tectonic contraction of the Laramide (about 70 Ma to about 40 Ma) orogeny. Renewed uplift and structural modification of these mountains has occurred during formation of the Rio Grande rift. Surficial deposits in the study area include alluvial, mass-movement, and glacial deposits of middle Pleistocene to Holocene age.

New Mexico↗
USGS1953

Pre-Cambrian geology of the Norway Lake area, Dickinson County, Michigan

The Norway Lake area straddles the south margin of the Sagola basin, an embayment of Ruronian sedimentary rocks into the west side of a complex of crystalline and sedimentary rocks of pre-Ruronian age. The north part of the Norway Lake area is underlain by the Randville dolomite, an unnamed succession of slates, Vulcan iron-formation, and interbedded slates and graywackes of the Sagola basin. The Sturgeon quartzite has not been definitely recognized in the Norway Lake area. The Handville dolomite is more than 800 feet thick and can be subdivided into upper and lower dolomite members separated by a slate member. The Vulcan iron-formation and the footwall slates are exposed only in the Deerhunt exploration. A thick section of red and gray slates with interbedded graywacke, of probable Upper Huronian age, underlies the northwest part of the mapped area. The south part of the Norway Lake area is underlain by granite gneiss, an arkose series, and schists, all of pre-Huronian age. The principal structural elements of the Norway Lake area are high angle faults, and such faults form most of the boundary between Huronian and pre-Huronian rocks in the area. The structure of the Huronian rocks. particularly in the vicinity of the Deerhunt exploration, cannot be determined with certainty on the basis of information now available. Magnetic anomalies were found to be associated with the slate member of the Randville dolomite, basalt interbedded with the arkose series, and a magnetite-bearing member in hornblende schist. It is possible that economic deposits of iron ore occur within the mapped area. However, exploration will be tedious and costly because of the structural complexity of the area and the paucity of exposures. Furthermore, the absence of strong magnetic anomalies, such as typically are present in areas known to be underlain by Vulcan iron-formation, suggests that the iron-formation is not present in abundance; in fact, it may be limited to the immediate vicinity of the Deerhunt exploration. Field mapping and petrographic examination do not provide data to determine whether the granite gneiss formed from a magma. Chemical analysis of one sample suggests that it was formed from rocks of the earth's crust rather than by fractional crystallization of a basaltic magma. The original feldspars of the granite gneiss were probably anorthoclase and analbite. During uplift and denudation these were changed to microcline microperthite and albite. These feldspars were contributed to the arkose series. During regional metamorphism of the granite gneiss and arkose replacement type microperthite and secondary perthite were formed, probably by redistribution of feldspars already present tither than by metasomatism.

Michigan↗
USGS1998

Geologic map of Paleozoic rocks in the Calico Hills, Nevada Test Site, southern Nevada

The Calico Hills area in the southwestern part of the Nevada Test Site, Nye County, Nevada, exposes a core of pre-Tertiary rocks surrounded by middle Miocene volcanic strata. This map portrays the very complex relationships among the pre-Tertiary stratigraphic units of the region. The Devonian and Mississippian rocks of the Calico Hills are distinct from age-equivalent carbonate-shelf or submarine-fan strata in other parts of the Nevada Test Site. The Calico Hills strata are interpreted to have been deposited beyond the continental shelf edge from alternating silicic and carbonate clastic sources. Structures of the Calico Hills area record the compounded effects of: 1) eastward-directed, foreland-vergent thrusting; 2) younger folds, kink zones, and thrusts formed by hinterland-vergent deformation toward northwesterly and northerly directions; and 3) low-angle normal faults that displaced blocks of Middle Paleozoic carbonate strata across the contractionally deformed terrane. All of these structures are older than any of the middle Miocene volcanic rocks that were erupted across the Calico Hills.

Nevada↗
USGS2013

Characterization of hydrodynamic and sediment conditions in the lower Yampa River at Deerlodge Park, east entrance to Dinosaur National Monument, northwest Colorado, 2011

The Yampa River in northwestern Colorado is the largest, relatively unregulated river system in the upper Colorado River Basin. Water from the Yampa River Basin continues to be sought for a number of municipal, industrial, and energy uses. It is anticipated that future water development within the Yampa River Basin above the amount of water development identified under the Upper Colorado River Endangered Fish Recovery Implementation Program and the Programmatic Biological Opinion may require additional analysis in order to understand the effects on habitat and river function. Water development in the Yampa River Basin could alter the streamflow regime and, consequently, could lead to changes in the transport and storage of sediment in the Yampa River at Deerlodge Park. These changes could affect the physical form of the reach and may impact aquatic and riparian habitat in and downstream from Deerlodge Park. The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, began a study in 2011 to characterize the current hydrodynamic and sediment-transport conditions for a 2-kilometer reach of the Yampa River in Deerlodge Park. Characterization of channel conditions in the Deerlodge Park reach was completed through topographic surveying, grain-size analysis of streambed sediment, and characterization of streamflow properties. This characterization provides (1) a basis for comparisons of current stream functions (channel geometry, sediment transport, and stream hydraulics) to future conditions and (2) a dataset that can be used to assess channel response to streamflow alteration scenarios indicated from computer modeling of streamflow and sediment-transport conditions.

Colorado↗
USGS2017

Overview for geologic field-trip guides to Mount Mazama, Crater Lake Caldera, and Newberry Volcano, Oregon

These field-trip guides were written for the occasion of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial scientific assembly in Portland, Oregon, in August 2017. The guide to Mount Mazama and Crater Lake caldera is an updated and expanded version of the guide (Bacon, 1989) for part of an earlier IAVCEI trip to the southern Cascade Range. The guide to Newberry Volcano describes the stops included in the 2017 field trip. Crater Lake and Newberry are the two best-preserved and most recent calderas in the Cascades Volcanic Arc. Although located in different settings in the arc, with Crater Lake on the arc axis and Newberry in the rear-arc, both volcanoes are located at the intersection of the arc and the northwest corner region of the extensional Basin and Range Province.

Oregon↗
USGS1996

Three-dimensional crustal structure of the southern Sierra Nevada from seismic fan profiles and gravity modeling

Traveltime data from the 1993 Southern Sierra Nevada Continental Dynamics seismic refraction experiment reveal low crustal velocities in the southern Sierra Nevada and Basin and Range province of California (6.0 to 6.6 km/s), as well as low upper mantle velocities (7.6 to 7.8 km/s). The crust thickens from southeast to northwest along the axis of the Sierra Nevada from 27 km in the Mojave Desert to 43 km near Fresno, California. A crustal welt is present beneath the Sierra Nevada, but the deepest Moho is found under the western slopes, not beneath the highest topography. A density model directly derived from the crustal velocity model but with constant mantle density satisfies the pronounced negative Bouguer anomaly associated with the Sierra Nevada, but shows large discrepancies of >50 mgal in the Great Valley and in the Basin and Range province. Matching the observed gravity with anomalies in the crust alone is not possible with geologically reasonable densities; we require a contribution from the upper mantle, either by lateral density variations or by a thinning of the lithosphere under the Sierra Nevada and the Basin and Range province. Such a model is consistent with the interpretation that the uplift of the present Sierra Nevada is caused and dynamically supported by asthenospheric upwelling or lithospheric thinning under the Basin and Range province and eastern Sierra Nevada.

California↗
USGS2023

Bedrock-surface elevation and overburden thickness maps of the five boroughs, New York City, New York

Digital maps of bedrock elevation and overburden thickness (depth to bedrock) were constructed for the five boroughs of New York City by the U.S. Geological Survey, in cooperation with the New York City Department of Design and Construction, from a compilation of historical and newly acquired data. Raster surfaces were interpolated from a point database containing data from more than 14,000 locations collected from a variety of sources. These data were collected between 1905 and 2021. These maps were constructed to supplement existing tools for the evaluation of potential construction of geothermal heat pump technology for buildings in New York City. The bedrock underlying the study area ranges from easily weathered to very resistant to weathering. This differential susceptibility to erosion, along with numerous north-northwest-trending faults, is believed to control the shape of the bedrock surface. Glacial scouring of the bedrock during the Pleistocene Epoch is the most recent control on the topography of bedrock surfaces. Overburden thickness is an important consideration for evaluation and construction of geothermal systems. Bedrock-surface elevation ranges from about 360 feet above sea level (in central Staten Island and northern Bronx) to 1,200 feet below sea level (in southern Queens) (North American Vertical Datum of 1988). The overburden thickness ranges from 0 foot thick at surface outcrops on Staten Island, Manhattan, and the Bronx, to 1,280 feet thick in southeastern Queens.

Data Report↗
USGS2016

Gravity and magnetic studies of the eastern Mojave Desert, California and Nevada

Introduction From May 2011 to August 2014, the U.S. Geological Survey (USGS) collected gravity data at more than 2,300 stations and physical property measurements on more than 640 rock samples from outcrops in the eastern Mojave Desert, California and Nevada. Gravity, magnetic, and physical-property data are used to study and locate regional crustal structures as an aid to understanding the geologic framework related to mineral resources of the eastern Mojave Desert. The eastern Mojave Desert is host to a world-class rare earth element carbonatite deposit located at Mountain Pass, California. Carbonatites are typically defined as magmatic rocks with high modal abundances of primary carbonate minerals >50 weight percent and elevated abundances of rare earth elements (REEs) (Nelson and others, 1988; Woolley and Kempe, 1989). The “Sulphide Queen” carbonatite ore deposit is a composite, tabular body made up of sills and dikes of REE-bearing sovites and beforsites that occurs just south of the Clark Mountain Range along a north-northwest trending fault-bounded block that extends along the northeast edge of the Mescal Range and northwestern extent of Ivanpah Mountains. This early to middle Proterozoic block is composed of a 1.7 Ga metamorphic complex of gneiss and schist that underwent widespread metamorphism and associated plutonism during the Ivanpah orogeny (Miller and others, 2007). Subsequently, these rocks were intruded by a series of granitoids, which included the 1.4 Ga (DeWitt and others, 1987) ultrapotassic alkaline suite of intrusions that are spatially and temporally associated with hundreds of dikes, outcrops, and a carbonatite ore body. The relative age sequence of this intrusive suite of alkaline rocks from oldest to youngest includes shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, and late shonkinite dikes (Olson and others, 1954; Wooden and Miller, 1990; Haxel, 2005; Miller and others, 2007).

California, Nevada↗
USGS2002

An integrated geophysical and hydraulic investigation to characterize a fractured-rock aquifer, Norwalk, Connecticut

The U.S. Geological Survey conducted an integrated geophysical and hydraulic investigation at the Norden Systems, Inc. site in Norwalk, Connecticut, where chlorinated solvents have contaminated a fractured-rock aquifer. Borehole, borehole-to-borehole, surface-geophysical, and hydraulic methods were used to characterize the site bedrock lithology and structure, fractures, and transmissive zone hydraulic properties. The geophysical and hydraulic methods included conventional logs, borehole imagery, borehole radar, flowmeter under ambient and stressed hydraulic conditions, and azimuthal square-array direct-current resistivity soundings. Integrated interpretation of geophysical logs at borehole and borehole-to-borehole scales indicates that the bedrock foliation strikes northwest and dips northeast, and strikes north-northeast to northeast and dips both southeast and northwest. Although steeply dipping fractures that cross-cut foliation are observed, most fractures are parallel or sub-parallel to foliation. Steeply dipping reflectors observed in the radar reflection data from three boreholes near the main building delineate a north-northeast trending feature interpreted as a fracture zone. Results of radar tomography conducted close to a suspected contaminant source area indicate that a zone of low electromagnetic (EM) velocity and high EM attenuation is present above 50 ft in depth - the region containing the highest density of fractures. Flowmeter logging was used to estimate hydraulic properties in the boreholes. Thirty-three transmissive fracture zones were identified in 11 of the boreholes. The vertical separation between transmissive zones typically is 10 to 20 ft. Open-hole and discrete-zone transmissivity was estimated from heat-pulse flowmeter data acquired under ambient and stressed conditions. The open-hole transmissivity ranges from 2 to 86 ft2/d. The estimated transmissivity of individual transmissive zones ranges from 0.4 to 68 ft2/d. Drawdown monitoring in nearby boreholes under pumping conditions identified hydraulic connections along a northeast-southwest trend between boreholes as far as 560 ft apart. The vertical distribution of fractures can be described by power law functions, which suggest that the fracture network contains transmissive zones consisting of closely spaced fractures surrounded by a less fractured and much less permeable rock mass.

Connecticut↗
USGS2010

Rejuvenation of the Kuqa Foreland Basin, northern flank of the Tarim Basin, northwest China

The Kuqa depression along the northern flank of the Tarim basin is filled with a thick sequence of Neogene and Quaternary coarse elastic continental sediments. This structural depression is part of a large foreland basin that lies south of the Tianshan—an orogenic belt of intracontinental convergence resulting from the northward propagation of stress following the collision of India with the southern margin of Eurasia.

Kuqa Foreland Basin, Tarim Basin↗
USGS1990

Variations in fluvial deposition on an alluvial plain: An example from the Tongue River Member of the Fort Union Formation (Paleocene), southeastern Powder River Basin, Wyoming, U.S.A.

The Tongue River Member of the Paleocene Fort Union Formation is an important coal-bearing sedimentary unit in the Powder River Basin of Wyoming and Montana. We studied the depositional environments of a portion of this member at three sites 20 km apart in the southeastern part of the basin. Six lithofacies are recognized that we assign to five depositional facies categorized as either channel or interchannel-wetlands environments. (1) Type A sandstone is cross stratified and occurs as lenticular bodies with concave-upward basal surfaces; these bodies are assigned to the channel facies interpreted to be the product of low-sinuosity streams. (2) Type B sandstone occurs in parallel-bedded units containing mudrock partings and fossil plant debris; these units constitute the levee facies. (3) Type C sandstone typically lacks internal structure and occurs as tabular bodies separating finer grained deposits; these bodies represent the crevasse-splay facies. (4) Gray mudrock is generally nonlaminated and contains ironstone concretions; these deposits constitute the floodplain facies. (5) Carbonaceous shale and coal are assigned to the swamp facies. We recognize two styles of stream deposition in our study area. Laterally continuous complexes of single and multistoried channel bodies occur at our middle study site and we interpret these to be the deposits of sandy braided stream systems. In the two adjacent study sites, single and multistoried channel bodies are isolated in a matrix of finer-grained interchannel sediment suggesting deposition by anastomosed streams. A depositional model for our study area contains northwest-trending braided stream systems. Avulsions of these systems created anastomosed streams that flowed into adjacent interchannel areas. We propose that during late Paleocene a broad alluvial plain existed on the southeastern flank of the Powder River Basin. The braided streams that crossed this surface were tributaries to a northward-flowing, basin-axis trunk stream that existed to the west.

Wyoming↗
USGS1964

Subsurface geology of the upper Cretaceous Kirtland and Fruitland formations of the San Juan Basin, New Mexico and Colorado

The San Juan Basin is an asymmetrical structural basin in northwestern New Mexico and southwestern Colorado. The basin contains sedimentary rocks ranging from Cambrian through Recent in age and attaining a maximum thickness between 14,000 and 15,000 feet. The Upper Cretaceous sedimentary rocks exceed 8,000 feet in thickness and can be divided into two groups: the lower Upper Cretaceous which is composed of the non marine and non-marine rocks and the upper Upper Cretaceous which is composed of the non-marine Kirtland and Fruitland Formations. The Kirtland Shale is subdivided into the lower shale, Farmington Sandstone, and upper shale members. The rocks of the Kirtland and Fruitland Formations consist of fluviatile and flood plain deposits and range in thickness from 1750 feet in the northwest part of the basin to 0 feet on the eastside of the basin. The thinning of the Kirtland and Fruitland Formations from west to east is primarily the result of erosion following tilting of the San Juan Basin area toward the west after either part or all of the upper shale member had been deposited. The overlying Ojo Alamo Sandstone rests on progressively older rocks across the basin overstepping the under lying upper shale member, Farmington Sandstone Member, Fruitland Formation, and finally resting on the Lewis Shale on the east side of the basin. The source area for the rocks of the Kirtland and Fruitland Formations was probably to the north or northwest of the San Juan Basin area. The Kirtland and Fruitland rocks have produced minor amounts of oil and gas. The Fruitland Formation contains large coal deposits some of which are currently being strip mined near Fruitland, New Mexico

Colorado, New Mexico↗
USGS2011

Regional-scale stratigraphy of surface units in Tyrrhena and Iapygia Terrae, Mars: Insights into highland crustal evolution and alteration history

The compositional, thermophysical and geologic characteristics of surface units in Iapygia and Tyrrhena Terra (60°E–100°E, 0°–30°S) provide new insights into the compositional stratigraphy of the region. Intercrater plains are dominated by two surface units. The older unit (unit 1) is deficient in olivine and more degraded and likely consists of a mixture of impact, volcanic and sedimentary materials. The younger unit (unit 2) is enriched in olivine, exhibits a resistant morphology and higher thermal inertia, and likely represents volcanic infilling of plains. Units 1 and 2 bear a strong resemblance to those previously mapped in Mare Serpentis, a section of highlands crust located northwest of Hellas Basin. Thus, the two major intercrater plains units are even more widespread than previously thought and therefore likely constitute important components of Mars' highland stratigraphy. Many craters in the region contain high thermal inertia deposits (unit 3) that are compositionally identical to unit 2. These may have formed via volcanic infilling or may represent sedimentary materials that have been eroded from crater walls and lithified. Less common units include olivine and/or pyroxene‐rich massifs and crater central peaks. These are primarily found within Hellas Basin rim units and may represent mantle materials brought toward the surface during the Hellas impact. Putative chloride deposits are primarily associated with olivine‐deficient surfaces (unit 1) that may be heavily degraded occurrences of unit 2. The observations raise a variety of questions related to Martian crustal evolution and alteration that may have more widespread implications outside the study region.

Journal of Geophysical Research - Planets↗
USGS1967

Preliminary geologic section from Pahute Mesa, Nevada Test Site, to Enterprise, Utah

The 154-mile long geologic cross section trends nearly perpendicular to the structural grain of the Basin-Range province in Nevada, and in Utah extends eastward into the transition zone between the Basin-Range and Colorado Plateau provinces. The structure is characterized by complex thrust: faults, involving uppermost Precambrian to lower Mesozoic sedimentary rocks, and normal faults which cut: the thick sequence of Tertiary volcanic rocks as well as older rocks. Some of the normal faults are the result of caldera collapse. The principal normal faults trend northerly west: of Delamar, Nev., and form north-trending basins and ranges. Farther east the principal faults trend northwesterly, and form a moderately rugged highland rather than distinct basins and ranges. The uppermost Precambrian-Paleozoic strata thin markedly eastward across the region. The pre-Pennsylvanian sedimentary rocks vary from 32,500 feet: in thickness at the Nevada Test: Site (Harley Barnes, E. N. Hinrichs, F. A. McKeown and P. P. Orkild, written commun., 1963) to 4,500 feet: in the Beaver Dam Mountains in western Utah (Cook, 1960). Thick Mesozoic deposits, similar to those of the Colorado Plateau, are present in western Utah, but are represented in eastern Nevada by only thin patches of Triassic rock.

Nevada, Utah↗