USGS Science⌕ Search

Geology topics

Research about Texas

Source-linked reports with geographic coverage including Texas.

At least 1,225 records · Page 68Linked to original sources
USGS1976

The water quality of Livingston Reservoir on the Trinity River, Southeastern Texas

The concentrations of dissolved solids, chloride, and sulfate in Livingstone Reservoir on the Trinity River in southeastern Texas usually average less than 250 mg/1 (milligrams per litre), 40 mg/1, and 50 mg/1, respectively. The water is usually hard or moderately hard (61 to 180 mg/1 as calcium carbonate). The concentrations of principal dissolved constituents in the reservoir are usually maximum during summer and fall when evaporation is high and inflow is low. Thermal stratification of the reservoir usually begins in March and persists until September or October. Neither the seasonal variation of dissolved constituents in inflow to the reservoir nor thermal stratification has resulted in significant stratification of the principal dissolved constituents. However, thermal stratification has resulted in significant seasonal and areal variations of dissolved oxygen, which results in higher concentration of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen.

Texas↗
USGS1976

Statistical analysis of water-level, springflow, and streamflow data for the Edwards Aquifer in south-central Texas

Water-level, springflow, and streamflow data were used to develop simple and multiple linear-regression equations for use in estimating water levels in wells and the flow of three major springs in the Edwards aquifer in the eastern San Antonio area. The equations provide daily, monthly, and annual estimates that compare very favorably with observed data. Analyses of geologic and hydrologic data indicate that the water discharged by the major springs is supplied primarily by regional underflow from the west and southwest and by local recharge in the infiltration area in northern Bexar, Comal, and Hays Counties.

Texas↗
USGS1976

Regional appraisal of the Wilcox Group in Texas for subsurface storage of fluid wastes: Part 1: Geology

Sandy beds of the Wilcox Group in Texas are underlain and overlain by clays of the Midway and Claiborne Groups. The Wilcox is divided by a persistent shale wedge. Contrasting delta systems described as high-constructive and high-destructive exist in the divisions. Merged high constructive deltas characterize the lower, while the upper Wilcox was deposited as a high destructive system. Maximum sand development occurs downdip parallel to regional depositional strike in the delta facies. Further downdip, shales replace sands, and sediments are (abnormally high pressured) geopressured. The structure o5 the updip port[on is that of a stable shelf. Downdip, greatly thickened beds are cut by large faults. These faults and the resultant deposits are recognized as being the result of a previously unnamed phenomenon--here termed hydrothermal tectonism. This process is keyed to the thermal diagenesis of the clay mineral montmorillonite and resultant transfer of overburden pressure from the rock framework to the contained fluid.

Texas↗
USGS1976

Chemical and bacteriological quality of water at selected sites in the San Antonio area, Texas, August 1968-January 1975

Urban development on or adjacent to the recharge zone of the Edwards aquifer is causing concern about the possible pollution of ground water in the aquifer, which is the principal source of water supply for the San Antonio area. Water-quality data for many wells and springs and for selected sites on streams that cross the recharge zone of the aquifer are being collected to provide background information and to detect any current pollution of ground water in the area. Water from the Edwards aquifer is very hard and of the calcium bicarbonate type. The concentrations of dissolved solids in samples from wells and springs ranged from about 200 to 470 mg/1 (milligrams per liter); the chloride and sulfate concentrations ranged from 6.5 to 62 mg/1 and from 0.0 to 65 mg/1, respectively. The nitrate and phosphate contents of the ground water ranged from 0.0 to 15 mg/1 and from 0.00 to 0. 37 mg/1. The concentrations of these and other constituents show that the chemical quality of water in the Edwards aquifer has not been degraded significantly by domestic, industrial, or agricultural effluents. However, variations in the number of coliforms, the concentrations of nitrate and phosphate, and the presence of fecal coliforms and fecal streptococci in samples from some wells show that fecal pollution is reaching the aquifer. Most of these wells, which are located in or just downdip from the recharge zone, are poorly sealed or inadequately cased. The areal variation in the locations of these wells indicates that pollution of ground water in the aquifer is very localized. Prllution results principally from runoff from the land surface and from effluent from septic tanks which enters the aquifer through fractures in the recharge zone or which infiltrates through the thin soil into poorly sealed or inadequately cased wells in or adjacent to the recharge zone. Trace amounts of several pesticides have been detected in samples from two wells in the San Antonio area. Field investigations showed the source of pesticides in these wells to be. surface drainage that entered the wellbores. Water-quality data collected at sites on streams that cross the recharge zone of the Edwards aquifer show the chemical composition of surface water to be very similar to that of ground water in the area. Water in most streams is very hard and of the calcium bicarbonate type. Limited data on the bacteriological quality show that coliforms were present at each of the site sampled and that fecal coliforms and fecal streptococci were present at most sites. Although the number of these bacteria varied greatly in both time and place, their density in samples from most sites were low for untreated surface water.

Texas↗
USGS1976

Progress report on geology of the Edwards aquifer, San Antonio area, Texas, and preliminary interpretation of borehole geophysical and laboratory data on carbonate rocks

This report describes the geology and porosity of the rocks of the Edwards aquifer, with particular attention to the eastern half of the San Antonio area. The data were obtained from geologic and geophysical studies of nine cored test holes, from laboratory analyses of samples of the aquifer materials, and from recent stratigraphic studies by other investigators. The Georgetown Formation and the Edwards Group or their equivalent stratigraphic units are extensively exposed in central Texas and they occur in the subsurface throughout southern Texas. They consist of a complex sequence of carbonate rocks deposited during Early Cretaceous time under different depositional conditions. Within the study area, the thickness of the carbonate rocks ranges from less than 400 feet (122 m) in the eastern part of the area to more than 600 feet (183 m) in the southwestern part. The depositional environments significantly affected the texture and the composition of the sediments. The Maverick Basin in the southwestern part of the study area was a euxinic basin surrounded by a barrier rudistid reef. Fine-grained carbonates and some associated evaporites occur within this basin. The San Marcos Platform in the eastern part of the study area was intermittently submerged by a transgressing continental sea. Much of the sediments are extensively reworked and burrowed by marine organisms. Several thick sequences of dolomites, evaporites, and associated collapsed deposits occur on the San Marcos Platform. The carbonates of the San Marcos Platform are extensively dissolved within the fresh-water zone. Much of the dissolution is selective of beds containing evaporites or porous dolomites. The dominant structural feature of the study area is a broad homocline that extends from nearly flat-lying beds on the Edwards Plateau to steeply dipping beds of the deep subsurface of the Gulf Coastal Plain. The homocline is interrupted by the Balcones Fault Zone, which is a zone of normal faults that extend across the study area. The intensity and complexity of faulting increases eastward as part of a progression from gentle flexures in the southwestern part of the study area to a complex pattern of tilted fault blocks on the San Marcos Platform.

Texas↗
USGS1976

Time of travel of solutes in the East Fork Trinity River, November 1975; and Elm Fork Trinity River, December 1975; Trinity River basin, Texas

The U.S. Geological Survey, in cooperation with the North Central Texas Council of Governments, the Trinity River Authority of Texas, and the Texas Water Development Board, conducted two time-of-travel studies in the Trinity River basin in November and December, 1975. Field data were collected on the East Fork Trinity River during November 18-22, 1975, and on the Elm Fork Trinity River during December 8-13, 1975. The purpose of these two studies was to provide data that could be used by the Trinity River Authority and the Texas Water Quality Board in the development of a mathematical water-quality model of the two streams. The model is to be used in a comprehensive water-quality management plan for the Trinity River basin.

Texas↗
USGS1976

Hydrologic data for Little Elm Creek, Trinity River basin, Texas, 1976

This report contains rainfall, runoff, and storage data collected during the 1976 water year for a 75.5 sq mi area above the stream-gaging station Little Elm Creek near Aubrey, Texas. Floodflows from 35.7 sq mi of the area are regulated by 16 floodwater-retarding structures constructed by the Soil Conservation Service. During the 1976 water year, five storm periods were selected for detailed computations and analyses. Beginning with the 1975 water year, water-quality data is given for Little Elm Creek. Investigations in the Little Elm Creek watershed were terminated on September 30, 1976.

Texas↗
USGS1976

Hydrologic data for urban studies in the San Antonio, Texas metropolitan area, 1976

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Dallas, Dallas County, Fort Worth, Houston, and San Antonio. The Geological Survey, in cooperation with the Texas Department of Water Resources, expanded the existing streamflow network in the San Antonio metropolitan area in May 1968 to begin urban hydrology studies in this area. In September 1968, the program was further expanded to include the collection of water-quality data.

Texas↗
USGS1976

Digital model for simulated effects of ground-water pumping in the Hueco Bolson, El Paso Area, Texas, New Mexico, and Mexico

The Hueco Bolson provides a substantial part of the municipal and industrial water supply of the El Paso area of Texas, New Mexico, and Mexico. Although the supply 6f fresh ground water in the bolson is large, about 10.6 million acre-feet (13,070 hm 3 ) in 1973 in the Texas part of the bolson alone, the supply is being depleted. A two-layer digital model of the Hueco Bolson was developed to duplicate the historic changes in water levels and the predevelopment (1903) water surface, and'to predict the response of the hydrologic system to any plan of water development. The model study showed that a proposed plan of development for 1973-91, in which pumping would be increased by 29 percent in the Texas part of the bolson and by 34 percent in Ciudad Juarez, would cause additional waterlevel declines of as much as 45 feet (13.7 m) in the vicinity of El Paso and 70 feet (21.3 m) in Ciudad Juarez. The study also showed that nearly 60 percent of the water would come from storage in the water-table part of the bolson aquifer (model layer 2) and 28 percent from leakage from the alluvium (model layer 1). By the end of the period, 9.84 million acrefeet (12,133 hm 3 ) of fresh water would be in storage in the Texas part of the bolson, as compared to 10.6 million acre-feet (13,070 hm 3 ) in storage in 1973.

Texas↗
USGS1976

Land-surface subsidence in the area of Moses Lake near Texas City, Texas

Removal of water, oil, and gas from the subsurface in Harris and Galveston Counties has caused declines in fluid pressures, which in turn have resulted in subsidence of the land surface. Subsidence of the land surface at Moses Lake in due principally to the removal of ground water in adjacent areas. Significant subsidence of the land surface at Moses Lake began after 1900, and as much as 1.8 feet of subsidence had occurred in the ara by 1973. Probable future subsidence was calculated by two methods for two loading situations. In the first loading situation, the artesian head in the middle Chicot aquifer, in the Alta Loma Sand (Rose, 1943), and in the Evangeline aquifer would continue to decline at respective rates of 1, 3, and 3 feet per year until 1980 and then cease. In the second loading situation, the artesian head in the middle Chicot aquifer, in the Alta Loma Sand, and in the Evangeline aquifer would continue to decline at respective rates of 1, 3, and 3 feet per year until 1990 and then cease.

Texas↗
USGS1976

Textural distribution of sea-floor sediments, south Texas Outer Continental Shelf

The general texture of sea-floor sediments along the south Texas Outer Continental Shelf was evaluated in terms of gravel, sand, silt, and clay components. The gravel component is quantitatively minor and is concentrated mainly in the southern sector; it consists, for the most part, of relict biogenic detritus dominated by molluscan shells. The sand component consists of terrigenous and biogenic detritus. Modern sand is localized along the shoreface sector, whereas palimpsest and relict sands characterize the northern and southern sectors, which are the respective locations of the ancestral Brazos-Colorado 'and Rio Grande deltas. The central sector contains an extensive modern mud blanket that appears to be migrating southward over relict deposits of the ancestral Rio Grande delta. The silt fraction is the highly dominant component of the mud blanket; silt appears to be hydraulically trapped within the shelf environment and constitutes the most abundant detrital component within the Outer Continental Shelf region. The subordinate clay component of the mud blanket is concentrated toward the shelf break and may be largely escaping into deeper water environments.

Texas↗
USGS1976

Sedimentary depositional environments of uranium and petroleum host rocks of the Jackson Group, south Texas

Determination of depositional environments in rocks of the Jackson Group of late Eocene age aids in the exploration for uranium and petroleum in south Texas. During deposition of the Jackson Group, conditions were similar to those existing along the modern Gulf Coast of Texas except for a less arid climate and a greater supply of volcanic sediment. Sedimentary depositional environments recognized in both the modern coast and the Jackson rocks, in order from sea toward land, are: shoreface, beach, lagoon and bay, and paludal. Sediment deposited in these environments in places is interbedded with or transected by fluvial sediment. Both uranium and petroleum are found in the shoreface, beach, and fluvial facies. These facies are characterized by permeable well-sorted sandstone, which is commonly overlain and underlain by less permeable mudstone. A typical vertical sequence in ascending order through a unit containing a beach sandstone facies is (1) lagoonal or paludal clay stone and siltstone, (2) crossbedded fine-grained beach sandstone which contains Ophiomorpha burrows and, which, in places, is locally interbedded with lacustrine or lagoonal mudstone, (3) weakly laminated beach sandstone which contains root impressions at the top and Ophiomorpha , and (4) lagoonal or paludal claystone and siltstone. Gulfward, the beach sandstone apparently grades into highly burrowed, generally finer grained, more poorly sorted, less porous shoreface rocks. The beach facies may include barrier island beaches and mainland beaches, some of which were probably cheniers. Beach facies sandstone units extend many miles along the depositional strike, which nearly parallels the present outcrop strike, but extend only a mile or two (2-3 km) normal to the depositional strike into the subsurface. Recognition of the various facies in outcrops and drill holes is necessary for determination of true stratigraphic relations and for aid in exploration for beach and fluvial sandstone favorable for uranium and petroleum accumulations.

Texas↗
USGS1976

Geology of the Brysch uranium mine, Karnes County, Texas

Approximately 13,700 tons (12,400 tonnes) of oxidized uranium ore, averaging about 0.1 percent U 2 O 8 , was mined during 1966 and 1967 from the lower unit of the Deweesville Sandstone Member of the upper Eocene Whitsett Formation, from depths of 75 to 90 feet (23-27 m). The mine is in the Karnes County uranium area, 3 miles (5 km) east of Falls City, Tex. Meta-autunite, Ca(UO 2 ) 2 (PO 4 ) 2 2-6H 2 O, and meta-tyuyamunite, Ca(UO 2 ) 2 (PO 4 ) 2 3-5H 2 O, were identified in samples of the ore. The host rock is light-colored, medium-grained, well-sorted feldspathic sandstone that contains fossil wood and Ophiomorpha . It also contains clinoptilolite, cristobalite, and montmorillonite that probably formed as alteration products of volcanic grains in the original sediment. The host rock was deposited in a beach environment near or on a delta formed at the mouth of a stream channel oriented roughly normal to the beach. The Deweesville can be traced for many miles on the surface and represents in general the point of maximum transgression in a transgressive-regressive cycle. The upper unit of the Deweesville, which overlies the host rock, is now exposed in the mine and contains, in ascending order, storm-beach, shoreface, beach, and tidal-flat facies. The shape of the ore body suggests that it originated as an unoxidized ore roll. The ore-bearing fluids may have entered through porous fluvial rock extending updip. Plant material, abundant in the original host sediment, probably supplied reductant necessary for the roll formation.

Texas↗
USGS1975

Organochlorine insecticide residues in the free-tailed bat (Tadarida brasiliensis) at Bracken Cave, Texas

Fifty-nine free-tailed bats ( Tadarida brasiliensis mexicana ) were collected at Bracken Cave, Texas, and analyzed for organochlorine insecticides and polyehiorinated biphenyls (PCBs). Residues of DDE in the brain were greater in 12 young collected from the floor than in 15 young taken from the ceiling, but food deprivation, not higher residues in the brain, apparently caused young to fall. Among 18 pregnant females, residues of DDE and DDT were highest in yearlings. The first lactation by yearlings caused their residue loads to drop sharply. Thereafter, increasing age was accompanied by increasing residues but amounts generally did not exceed those in yearlings. Residue levels in embryos were a function both of levels in the female parent and degree of embryonic development. Residues accumulated rapidly in nursing young, and lactating females may excrete from 1.3 to 16.2 (mean = 4.3) micrograms of DDE in milk per day. Maximum individual residue loads may be attained toward the end of nursing, and mobilization of these residues during southward migration may subject Bracken Cave free-tails to maximum lifetime residues in the brain. Comparison of our data with residue data for the free-tail population at Eagle Creek Cave (Arizona) in 1970 produced the following conclusions: (1) residues of DDE appeared similar in pregnant females, embryos, lactating females, and fallen young for the two populations; (2) residues of DDT and dieldrin appeared greater in pregnant females at Bracken Cave; (3) DDE and DDT occurred at greater levels in guano samples from Bracken Cave. On this basis, the population decline observed at Eagle Creek Cave between 1963 and 1969 does not appear to be related to the residues observed in the 1970 samples taken from that cave.

Texas↗