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Source-linked reports with geographic coverage including Texas.

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Geology of part of the Horseshoe atoll in Borden and Howard Counties, Texas

The Horseshoe atoll is an arcuate mass of deeply buried fossiliferous limestone of Pennsylvanian and early Permian age in the Midland basin of west Texas. The southern part of the atoll is in southern Borden and northern Howard Counties. From early Strawn until early Wolf camp time this atoll, which had some of the characteristics of a reef, was a prominent feature on the floor of the Midland basin. The crest of the atoll is a series of buried hills and saddles. In the area of this report, 10 oil fields have been found in the hills along the crest, 2 on spurs on the flank of the atoll, 2 in the distant seaward area, and 2 on the seaward flank occupied by the central lagoon. Calcilutite, calcarenite, and calcirudite comprise most of the reef rock, but there are a few thin beds of shale. The complex facies relations and stratigraphy of this reef are best explained as effects of oscillation of sea level during the time of reef growth. The cementation of the reef and subsequent development of porosity can be explained by the same oscillations of sea level, plus leaching by ground water during the periods of emergence. Reef growth was terminated in early Wolfcamp time when large volumes of fine-grained terrigenous sediments were deposited in the area. The oil probably accumulated during Wolfcamp time shortly after the atoll was covered by black shale. Some peculiarities in the observed distribution of oil in the atoll may be explained by the apparent stratification of porosity.

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Chapter 22: Environments and facies of existing bays on the central Texas coast

The estuaries and neritic waters along the central Texas coast are characterized by broad ranges of environmental factors, providing conditions favorable to temperate organisms in winter and tropical organisms in summer. Dredging in the coastal waters revealed a number of distinct faunal facies, the distribution of which appears to be controlled primarily by salinity. Characteristic assemblages are found in the following areas: closed bays, polyhaline bays, a highly saline lagoon, passes, beaches on the open Gulf, and shallow waters of the open gulf. In the closed bays three subfacies are recognized-one in the bay heads, one on the reefs, and one in the interreef areas; in the open gulf the assemblages living close to shore are differentiated from those found 2-4 miles off shore. In most stations each facies is characterized by an abundance of certain living forms. Dead shells and other skeletal parts are much more widely distributed, but many such strays may be recognized as transported elements by their rarity or by their eroded surfaces. Each group of organisms has one or more centers of maximum development in numbers of species. The Foraminifera, for example, attain their greatest development in the polyhaline bays and near the heads of passes, the ostracodes near the bay heads, mollusks in the polyhaline bays and in the Gulf, and diatoms under normal marine conditions in the Gulf. The reef assemblage of the closed bays is poor in numbers of species, but the individuals are so numerous that they form extensive deposits.

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Delivery of water from Belton Reservoir to the Brazos River gaging station at Richmond, Texas, by way of the Leon, Little, and Brazos River channels, 1956

Beginning November 1, 1956 and ending December 14, 1956, the Corps of Engineers, in cooperation with the Brazos River Authority released 73,000 acre-feet of water (as measured at the gaging station on Leon river near Belton) from the Belton Reservoir for industrial use in the vicinity of Freeport, Tex. (see fig. 1). The need for this water at Freeport came as a result of the prolonged drought conditions causing flows in the Brazos River in the vicinity of Freeport to be insufficient to satisfy the industrial and other uses of vital importance.

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Texas floods of September and October 1955

This report on the floods of September and and October 1955 in the Nueces, Brazos, and Pecos River basins, Texas, was prepared in the Texas District Office, Surface Water Branch, under the direction of Trigg Twichell, District Engineer. Records of discharge were collected and compiled in cooperation with the Texas State Board of Water Engineers, the Pecos River Commission, and other agencies. The isohyetal map of the upper Brazos River basin, which was the basis for figure 4, was furnished by the Corps of Engineers. The "bucket" survey of rainfall in the Nueces River basin was conducted by the U.S. Weather Bureau, and the "bucket" survey in the upper Brazos River basin was conducted by the U.S. Weather Bureau, the Corps of Engineers, and the U.S. Soil Conservation Service. The U.S. Conservation Service furnished "A Report describing the effects of the storm of September 23-25, 1955, on the Upper Brazos River Watershed, above Possum Kingdom Dam" from which some data in this report were taken.

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Development of ground water from the Carrizo sand and Wilcox group in Dimmit, Zavala, Maverick, Frio, Atacosa, Median, Bexar, Live Oak, McMullen, La Salle, and Webb Counties, Texas

The development of ground water for irrigation from the Carrizo sand south and southwest of San Antonio, Tex., has increased rapidly during the past few years. Declining pumping water levels in irrigation wells, caused by increased withdrawals, have caused considerable concern among the residents of the area. In response, the Nueces River Conservation and Reclamation District entered into a cooperative agreement with the Texas Board of Water Engineers and the United States Geological Survey to determine the extent of development and the rate of withdrawal that has cause the decline. All wells that discharged more than 150 gallons per minute for extended periods of time in 1955 from either the Carrizo sand or sands of the Wilcox group were studied and are shown on [late 1. Estimates were made of the total withdrawals by county and are given in table 2. Similar estimates of withdrawals in some of the counties for the irrigation years 1929-30, 1938-39, 1944-45, and 1947-48 are presented for comparison in table 3. Although the Carrizo sand is the principal source of ground water pumped in the area, estimate of withdrawals of water from the Wilcox were included in this inventory because (1) the formation appears to be hydraulically connected to the Carrizo sand, (2) the quality of water generally is good in the outcrop area of the Wilcox, and (3) appreciable withdrawals are being made from the Wilcox for irrigation in a few areas. The investigation covered an area of about 7,500 square miles and included all or parts of the following counties: Dimmit, Zavala, Maverick, Frio, Atascosa, Medina, Bexar, Live Oak, McMullen, La Salle, and Webb (fig. 1).

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Salt water and its relation to fresh ground water in Harris County, Texas

Harris County, in the West Gulf Coastal Plain in southeastern Texas, has one of the heaviest concentrations of ground-water withdrawal in the United States. Large quantities of water are pumped to meet the requirements of the rapidly growing population, for industry, and for rice irrigation. The water is pumped from artesian wells which tap a thick series of sands ranging in age from Miocene (?) to Pleistocene. The water-bearing sands, many of which contained slightly saline water, are interbedded with clays. Subsequent artesian circulation has flushed the sands, probably to the limit determined by the Ghyben-Herzberg principle. The base of the fresh-water sands ranges in depth from about 100 feet over the salt dome near Hockley to more than 3,000 feet in the northeastern part of the county. Before large-scale ground-water withdrawals were begun, the hydraulic gradient sloped gently toward the coast. Then, as large quantities of water were withdrawn a large cone of depression was established, the hydraulic gradient was reversed, and salt water began to move slowly toward the centers of pumping. The rate of movement of the salt water is very slow and the closest salt water is probably 5 miles from centers of pumping in the deeper sands. However, the threat of salt-water intrusion is present and the rate of advance of the salt water should be watched by means of strategically placed observation wells. Other less probable potential sources of salt-water contamination which are discussed include upward movement of salt water from below, vertical movement around salt domes or along faults, downward seepage from surface sources, and contamination through leaking wells.

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Some uranium occurrences in west Texas

Uranium minerals have been found at several localities in west Texas. In the King Mountain area in southwestern Upton County carnotite forms coatings along joint planes and in borings in marine Cretaceous limestone. In the Hueco Mountains area in El Paso and Hudspeth Counties carnotite and similar secondary uranium minerals form coatings in caliche and collavium of Pleistocene(?) or Recent age, and along joints and bedding planes in Permian limestone. No uranium ore has been produced, however, from either area. In the King Mountain area, coatings of carnotite and tyuyamunite have observed from about 2 feet to a maximum of 7 1/2 feet below the surface of the ground in the Edwards limestone of Early Cretaceous age. One channel sample of the limestone in this area contained 0.002 percent U and 0.004 percent eU, and a small, selected sample of the mineral coatings contained 8.52 percent U and an estimated 3.7 percent eU. In the Hueco Mountains area, coatings of carnotite and tyuyamunite have been found on boulders in colluvial deposits, on fractures in a caliche matrix of the colluvium, and on joints and bedding planes in the underlying Hueco limestone and Permian age. In the colluvium, the coatings have been found to depths of 20 feet below the surface, and in the Hueco limestone they extend to depths of 12 to 15 feet below the surface, maximum depths penetrated by the prospect pits. Selected samples from the colluvial deposits contained as much as 0.01 percent eU and 0.023 percent U. Uranium minerals are reported in other widely scattered prospect pits along the west side of the Hueco Mountains. In both areas the minerals seem to have been deposited by ground water and are found in a zone generally less than 20 feet below the surface of the ground. Analyses show that in both areas the uranium is out of equilibrium with its decomposition products; the fact that normally uranium is greater than equivalent uranium suggests that the mineralization is relatively recent.

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The outlook for ground-water resources in Texas

The future of ground-water supplies in Texas presents a problem that is very important to the economy of Texas and to the well-being of almost every citizen of the state. It is of particular importance to more than 580 municipalities using ground water as the sole source of water supply; to many thousands of farmers using ground water for irrigation and also to others living in irrigated areas or dependent on irrigated agriculture for their livelihood, to more than 2 million people living in rural areas who are dependent on ground water for domestic supply, and to a large number of industries throughout the State, including some o the biggest ones.

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Geology of the Canyon Reservoir site on the Guadalupe River, Comal County, Texas

In response to a request by Colonel Harry O. Fisher, District Engineer of the Fort Worth District of the Corps of Engineers, United States Army (letter of Dec. 13, 1954), a reconnaissance investigation was made of the geology of the Canyon (F-1) reservoir site on the Guadalupe River in Comal County, Tex. The purpose of the investigation was to study the geology in relation to possible leakage - particularly leakage of water that might then be lost from the drainage area of the Guadalupe River - and to add to the general knowledge of the ground-water hydrology of the San Antonio area. The dam (F-1) was originally designed for flood control and conservation only, with provision for the addition of a power unit if feasible. Since the completion of the investigation by the Corps of Engineers, the city of San Antonio has expressed an interest in the reservoir as a possible source of public water supply. The Corps of Engineers has made a thorough engineering and geologic study of the dam site (Corps of Engineers, 1950), which has Congressional approval. The geology and water resources of Comal County have been studied by George (1952). The rocks studied are those within the reservoir area and generally below the 1,000-foot contour as shown on the Smithson Valley quadrangle of the U.S. Geological Survey.

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Double Moutain Fork Brazos River between Lubbock and Buffalo Lakes, Texas

The purpose of this investigation was to study quantity, quality, and possible sources of the low flow and spring inflow of the Double Mountain Fork of the Brazos River between the Lubbock sewage disposal plant, 3 miles southeast of Lubbock, and a County Road crossing about 15 miles downstream and 4.2 miles northeast of Slaton, Lubbock County (fig. 1).

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Diversions from Red River to Lake Dallas, Texas; and related channel losses, February and March 1954

During the period Feb. 10 to Mar. 3, 19541 the City of Dallas pumped 1,363 acre-feet of water from its Red River plant into Pecan Creek (a tributary of Elm Fork Trinity River) 3.5 miles above Gainesville; 1,272 acre-feet of this diversion reached the head of Lake Dallas. Discharge records were obtained at four points along the channels. This water was transported down the channels of Pecan Creek and Elm Fork Trinity River to Lake Dallas, a distance of about 31 miles.

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Peak discharge on Bull Creek and tributaries, Scurry and Borden Counties, Texas, flood of April 12, 13, 1954

This report contains a description of the rainfall pattern producing the flood of April 12, 13, 1954, in the Bull Creek watershed, the results of indirect determinations of peak discharges and estimates of flows at several points in that watershed, and a comparison of the peak stage at the discontinued gaging station on Bull Creek near Ira, Tex., with other floods on record. Field work consisted of transit-stadia surveys at five locations to develop high-water profiles and cross-sections, performed within two weeks after flood occurred.

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Floods in Devils and Pecos River basins of Texas, June 27-28, 1954 - miscellaneous data

Record-breaking floods occurred June 27, 28, 1954, in the Devils and lower Pecos Rivers and in some tributaries to those streams, caused by heavy rainfall of June 26-28. At the time of the flood the geological Survey was not operating a gaging station in the Devils River basin or in the Pecos river basin below Girvin. Continuous records of the flow of Devils River were obtained by the Geological Survey at the station at Baker's Crossing near Juno from May 1925 to September 1949 and on the Pecos River near Sheffield from October 1921 to April 1925 and from October 1939 to September 1949. Records of the great flood flows near the mouths of the Devils and Pecos Rivers mentioned above were obtained by the International Boundary and Water Commission, United States and Mexico, at gaging stations maintained by that agency on the Devils River near Del Rio and the Pecos River near Comstock. The outstanding nature of the flood in the lower Pecos River is shown by the fact that the maximum stage reached at the Comstock gaging station was 97.8 ft on June 27, 1954, whereas the maximum stage reached at this gage between the beginning of record in 1900 and 1954 was only 38.2 ft.

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Fluorspar deposits of the Eagle Mountains, Trans-Pecos Texas

The Eagle Mountains are in the southeastern part of Hudspeth County, Tex., about 17 miles southwest of Van Horn and 100 miles southeast of El Paso, Tex. The fluorspar deposits are in the northern and northeastern parts of the mountains, except for the Rocky Ridge deposits, which are near the center of the mountainous mass. A good all-weather road leads south from Allamoore on U. S. Highway 80 to the mine and mill at Spar Valley. With the exception of the Rocky Ridge deposits, all deposits can be reached by ranch roads from the main Spar Valley road. Fluorspar was first found in the Eagle Mountains in 1919, but no development was undertaken until 1942. Since then, mining has been done at Eagle Spring and at the various deposits in Spar Valley. Many other deposits have been found in the area. About 12,000 tons of fluorspar had been shipped previous to January 1949, most of which came from the North ore body in Spar Valley. A mill was built near the deposits In 1945. With the exception of the Eagle Spring and Tank Canyon deposits, both of minor importance, the fluorspar deposits as of 1950 are all controlled by Texas Fluorspar Mines, Inc., of Van Horn, Tex. Cretaceous sedimentary rocks, which crop out on the flanks of the mountains, are overlain by a thick series of Tertiary volcanics that make up much of the central part of the mountains. Low on the northeast side, the Cretaceous rocks are underlain by Permian (?) limestones and the pre-Cambrian Carrizo Mountain schist. The Cretaceous sedimentary rocks range from the Yucca formation of Early Cretaceous (lower Trinity) age through the Eagle Ford formation of Late Cretaceous age. The rocks on the northeast side of the mountains dip southwest, and those on the southwest and west sides dip east-northeast and northeast. The axis of the large syncline thus formed roughly parallels the axis of the range. The igneous rocks occur within the trough of the syncline. Both intrusive and extrusive rocks are present. The extrusive rocks have been separated into three divisions : the lower rhyolitic series, trachyte porphyry, and the upper rhyolitic series. Both rhyolitic series consist of flows, flow breccias, volcanic breccias, and tuffaceous sediments, all predominantly of rhyolitic composition, although tending toward andesite locally. These volcanics have been intruded by a small stock of syenite, named in this report the Eagle Peak syenite, which crops out in the central, higher parts of the mountains. Rhyolite sills have invaded the sedimentary rocks near the margin of the volcanics, and diabase and late rhyolite dikes have intruded both sedimentary and volcanic rocks. Faults are common in the area, and six series of faults have been recognized. Thrusting from the southwest occurred both before and after the igenous activity and the subsequent downwarping of the central part of the mountains. The early thrust faults were followed by high-angle normal and reverse faults that trend northeastward and cut the volcanics. Later normal and reverse faults trending northwestward, and faults with large horizontal displacements trending roughly eastward, also are present, in addition to very late faults trending in a general northwesterly direction. Fluorspar occurs in the Eagle Mountains both as replacement deposits in limestone and as fissure veins, chiefly in rhyolite. Chief among the fissure veins are those occurring along the Rhyolite fault, the Wind Canyon fault, the vein at Shaft 4, and the veins on Fox claims 9 and 10. The most important replacement deposits are in the Rocky Ridge area and in Spar Valley. • At the North ore body in Spar Valley, the fluorine-bearing solutions replaced a series of sandy limestones in the upper beds of the lower part of the Finlay formation. Structural conditions limited the extent of the replaceable beds and consequently of the fluorspar mineralization. The fluorine-bearing solutions represent a very late stage of the igneous activity of the area. The large east-trending faults with their wide zones of gouge and breccia, typified by the Rhyolite and Wind Canyon faults, acted as the major channels for the solutions in their upward course. From these faults, the solutions spread outward into other faults and fractures, chiefly those with a northeasterly trend, and into the adjoining limestones. The physical and chemical nature of the surrounding rock, as well as structural conditions affecting the presence of openings in the rock, were the major controlling factors governing the size, extent, and position of the fluorspar deposits.

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