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Mineral Resources of University Lands, Exclusive of Oil and Gas
(1971) Groat, C. G.; Rodda, Peter U.
This report describes and evaluates mineral resources, other than oil and gas, occurring on or beneath lands belonging to The University of Texas. The data utilized were derived from geologic mapping, field examination and sampling, laboratory analysis of samples, and compilation of available pertinent literature on the geology and mineral resources of University Lands and adjacent areas. The results of this study are presented in maps, sections, tables, and descriptive text that stress characteristics important in determining industrial or other economic use of the mineral resources.
Land-surface Subsidence and Active Faulting in the Texas Coastal Zone
(1974) Kreitler, Charles W.
Land-surface subsidence characterizes much of the Texas Coastal Zone, but is most common in the upper part of the Zone and especially in the greater Houston area. The degree of subsidence ranges from acute to that discernible only with precise instrument leveling. A number of factors can result in surface subsidence; however, the major cause in affected portions of the Texas Coastal Zone is the lowering of pressure heads due to the withdrawal of ground water. In local areas, subsidence has also been a function of the removal of oil and gas, and the solution mining of sulfur and salt. Other causes, significant in other areas, are insignificant in the Texas Coastal Zone.
Establishment of Operational Guidelines for Texas Coastal Zone Management
(1974) Kier, R. S.; White, William Allen, 1939-
A multidisciplinary team has been functioning at The University of Texas at Austin since 1971 to develop, apply, and evaluate methodology for considering environmental and economic effects of alternative Coastal Zone Management policies. The region encompassed by the Coastal Bend Council of Governments served as the test site for this project; special emphasis has been in the area around Corpus Christi Bay--Nueces, San Patricio, Aransas, and Refugio Counties. The principal purpose of the Bureau of Economic Geology task force of the multidisciplinary team was to provide an environmental baseline against which to measure the effects of economic and demographic development in the Corpus Christi area and probable differences among several hypothetical management policies. Operational criteria, which form this baseline, the systematic approach by which the locational effects of expansion were determined, and examples of the environmental impact of development are contained in this report. Forty land and water areas have been delineated in the Corpus Christi area, each with like capabilities to withstand similar kinds and rates of use or activity without losing an acceptable level of environmental quality. These data have been augmented by: (1) documenting the kinds, rates, and impetus of changes in dynamic shoreline environments; (2) relating engineering test results gathered by public agencies and private firms to physically defined land capability units on the Coastal Plain and in the bays; and (3) determining the distribution, amount, and quality of ground water available in the Corpus Christi area, and possible consequences of withdrawal of the ground water. Land and water resource data and current (1970) land-use data were digitized for automated processing from maps at a scale of 1:125,000. Environmental assessment is in terms of the kinds, amounts, and relative percentages of land and water resources and land-use types affected by growth in the Corpus Christi area.
Establishment of Operational Guidelines for Texas Coastal Zone Management in Corpus Christi Area, Texas, Resource capability units II: land resources of the Coastal Bend region, Texas
(1974) Kier, R. S.; White, William Allen, 1939-
Establishment of operational guidelines for effective management of the Texas Coastal Zone depends on comprehensive knowledge of the characteristics and distribution of natural and man-made environments. Forty-three land and water areas, each with like capabilities to withstand similar kinds and rates of use or activity without losing an acceptable level of environmental quality, have been delineated in the region encompassed by the Coastal Bend Council of Governments. Qualitative data on land and water capability derived from mapping surface and near-surface environments in the 13 counties of the COG have been augmented by: (1) documenting the kinds, rates, and impetuses of changes in dynamic shoreline environments; (2) relating engineering test results gathered by public agencies and private firms to physically defined land capability units of four of the counties; (3) determining the distribution, amount, and quality of ground water available in the Coastal Bend region, and areas most favorable for future development of ground water resources. Additional information has been gathered on the subsurface configuration of natural capability units and mineral resources in the region. This body of environmental data provided a basis for developing operational criteria against which the consequences of man's activities, future economic and demographic growth, and the effects of potential management policies were measured. Procedures used to evaluate the consequences of growth in the Corpus Christi area and the effects of implementing three land management policies in the Coastal Zone are discussed in a companion report: Environmental Impact of Economic and Demographic Expansion in the Corpus Christi Area--Methodology.
Depositional Framework of the Lower Dockum Group (Triassic), Texas Panhandle
(1975) McGowen, J. H.; Granata, G.; Seni, Steven J.
The Late Triassic Dockum Group of Texas and New Mexico is composed of 200 to 2,000 feet of complexly interrelated terrigenous clastic facies ranging from mudstone to conglomerate. The lower 200 to 1,000 feet of the Dockum accumulated in a fluvial-lacustrine basin defined by the Amarillo Uplift-Bravo Dome on the north and Glass Mountains on the south, and is the topic of this paper. Outcrop and subsurface data indicate that (1) the basin was filled peripherally, (2) sediment sources were in Oklahoma, Texas, and New Mexico, and (3) relict Paleozoic structures in concert with alternating humid and arid climatic cycles exerted considerable influence on the depositional style of the Dockum. An unconformity between the Permian and Triassic is obvious in the northern part of the basin, but physical evidence of an unconformity is lacking in the central basin area. Arid Permian conditions gave way gradually to more humid conditions of the Triassic. Initial deposits of the Dockum, which record these humid conditions, accumulated in: (1) braided and meandering streams; (2) alluvial fans and fan deltas; (3) high constructive lobate deltas; and (4) lakes. Alluvial fans and fan deltas were best developed in northern and southern parts of the basin, whereas central basin areas were dominated by high constructive lobate deltas. A change from humid to arid conditions produced (1) lowering of base level; (2) erosion (cannibalization) of older Dockum deposits; (3) replacement of meandering fluvial systems by headwardly eroding valleys and braided streams; and (4) development of small fan deltas. Several depositional cycles are recognized in the area defined by Dickens, Crosby, Kent, and Garza Counties. A cycle comprises facies that accumulated during one high- and one low-stand of lake level. Thin progradational delta and attendant meanderbelt systems were deposited during high-stand, relatively stable base-level conditions. Progradational delta sequences are composed of extrabasinal sediments ranging in texture from clay to gravel. A typical delta sequence consists of lacustrine and prodelta mudstone-siltstone, delta front siltstone-sandstone, channel mouth bar and distributary sandstone, and meanderbelt sandstone-conglomerate. Splay units, consisting of poorly sorted intrabasinal sandstone and conglomerate, are constituents of interdistribu- tary and floodplain deposits. Most delta sequences were partly cannibalized by superimposed meandering streams that migrated across the area. With a shift toward arid conditions, there was a lowering of base level accompanied by erosion of subjacent Dockum deposits. Sediment that composes the lowstand facies association ranges from reddish-brown mudstone to conglomerate. Abrupt vertical and lateral textural changes characterize these lowstand deposits. Lower Dockum red beds consist of lacustrine mudstone, prodelta mudstone-siltstone, delta front (delta foresets) siltstone to conglomerate, delta platform sandstone and conglomerate, and interdeltaic mudstone exhibiting desiccation features, and rare gypsum, salt hoppers, and chert.
Hazards Analysis, Building 950, Brooks Air Force Base, Bexar County, Texas
(1975) Chin, John L.; Jones, Leslie
Based on available information, building 950 is a suitable site for storage of lunar samples. The only apparent hazard is the high shrink-swell capacity of the soil. This soil property should be a primary consideration in any modifications made to the building.
Radioactive Waste Management by Burial in Salt Domes
(1975) Ledbetter, Joe O.; Kaiser, W. R.; Ripperger, E. A.
Questions regarding the suitability of salt domes as sites for high-level radioactive waste repositories are considered. Since wastes will have to be retained for thousands of years, the principal questions pertain to the geologic stability of the dome and the possibility of dissolution. No direct evidence is available to show that movement is positively not occurring in any salt dome. However, it is shown through geologic reasoning that the likelihood of movement of domes in the interior basins is extremely remote. If movement is occurring, it is taking place at such a slow rate as to present no problems. It is also believed that the likelihood of future movement as a result of geological activity within the storage time span is very remote. The possibility of dissolution to the point that it might become a threat to containment is found to be slight, particularly if the repository is surrounded by shale and below the base of fresh water or actively circulating groundwater. Other mechanisms which protect against dissolution are discussed, as well as evidence of dissolution, or non-dissolution in the past. The consequences of dissolution are also examined. Possible flooding of repositories in domes was found not to be a serious threat. Temperature rise data from Project Salt Vault are used to estimate temperature rises which might occur in domes, and some simplified calculations are made to determine the temperature rise that would occur under certain hypothetical conditions. These data indicate that heating, to the extent expected, poses no threat to dome stability. The available data indicate quite definitely that creep or plastic flow around a cavity mined in salt causes the cavity to close, but the rate of closure is so slow as to present no serious problems in the operation of a repository. Dome and bedded salt are compared as to their suitability for radioactive waste repository sites. Neither is superior to the other in an overall sense. In fact, depending upon the ultimate repository design, dome salt may be the preferred geologic formation. In a survey of all known domes, 29 were identified as potentially acceptable candidates for a waste repository. Objections to domes based on their future tectonic stability and hydrologic integrity can be met. Characteristics of the ideal dome for a radioactive waste repository are summarized. At least five domes meet most of the criteria of the ideal dome. Recommendations are made to enable the selection of the right dome.
In Situ Conversion of Texas Lignite to Synthetic Fuels
(1975) Edgar, Thomas F.; Kaiser, W. R.; Thompson, T. W.
A one-year technical and economic feasibility study to determine if the large deposits of deep basin Texas lignite can be recovered using in situ gasification has been completed. The study has consisted of engineering and geological analysis as well as limited experimentation. Since the project's inception in September 1974, a total of seven faculty and staff, ten graduate students, and seven undergraduates have been involved in the research. The principal funding for this project has been provided by the National Science Foundation, RANN division. Other research funds have been provided by Texas Utilities Company, Continental Oil Company, Mobil Oil Corporation, and the Shell Development Company. As of November 1975, the project is in phase with the goals as originally proposed for the one-year feasibility study on in situ gasification of Texas lignite. An economic model (computer program) for in situ gasification of Texas lignite has been completed. The results of this analysis indicate that in situ gasification by the percolation technique will be economic for depth to seam thickness ratios approaching 150 (compared to 15 for strip mining). The available operating data, mainly from Russian and British field tests as well as from the recent ERDA test in Wyoming, have been analyzed. A computer model of an in situ reactor has been completed, and it gives good agreement with previous field test results. Maps of lignite-bearing units in the Wilcox and Yegua formations have been prepared. This should help determine candidate field test sites as well as further clarify the Texas lignite resource picture. A review of the critical environmental factors has been undertaken, and the hydrological conditions for minimizing negative environmental effects have been established. Geological mapping of variables such as percent sand has indicated where environmentally feasible sites are located. The ALCOA strip mine near Austin is being used at present for a prototype lignite deposit. Chemical and physical property analyses are being run. An effective way to seal lignite cores at high temperatures has been developed. Combustion tube designs have been completed. Equipment to obtain mechanical properties of lignite and overburden has been constructed. Calculations on roof collapse can be facilitated with the above apparatus and a finite element computer program, which is nearly completed. The results of the one-year feasibility study have shown that in situ gasification of Texas lignite is technically and economically feasible, which warrants a two-year program of research and development to bring it to the field demonstration stage.
In Situ Conversion of Texas Lignite to Synthetic Fuels
(1976) Edgar, Thomas F.; Kaiser, W. R.; Thompson, T. W.
The current research on underground gasification of Texas lignite was initiated in September 1974. The initial phase of the work (1974-75) consisted of a technical and economic feasibility study. The results of that one-year study, as reported in a previous Semi-Annual Report (November 1975), indicated that in situ gasification of the large reserves of deep-basin Texas lignite would be quite attractive both technically and economically. In November 1975, experimental investigations were initiated to determine which geological, physical, and chemical conditions would be conducive to the application of underground gasification. Another goal of this project is the development of a mechanistic description of the dominant chemical and physical processes occurring during underground coal gasification; such models would provide a design basis for later field testing. The project staff currently consists of three principal investigators, plus an additional six faculty and staff, eight graduate students, and eight undergraduate students. The principal funding for this project has come from the National Science Foundation Research Applied to National Needs Program (RANN); a two-year grant was received in November 1975. Several private companies have also generously made contributions in support of the research program. These companies include Texas Utilities Services, Conoco, Shell, Dow, Mobil, Du Pont, and ARCO. These companies also provide technical advice to the research project. Since the nature of the research program has changed significantly during the last six months, with a heavy orientation on experimental aspects of the process, many of the individual research projects have just recently been initiated. Thus, only preliminary reports on their progress are available at this time. It is hoped that at the time of the next Semi-Annual Report, some substantive findings will be available. Experimental work in the areas of reaction kinetics, physical properties of lignite and overburden, and environmental impact are currently underway. More details on these efforts are contained in this report.
Mineral Production Values in Texas School Districts
(1976) Garner, L. E.; St. Clair, Anne E.
This investigation was initiated on January 15, 1976, when the Governor's Office, Education Resources Commission, designated the Bureau of Economic Geology as the performing agency to provide mineral production statistics for all school districts in the State of Texas. The final report includes the identification of all mineral commodities produced in Texas school districts and the evaluation of total mineral production value for each school district, including petroleum liquids, natural gas, and all other minerals. The inventory of active mineral producers and the evaluation of production and production value are based on data for the 1974 calendar year.
Land and Water Resources, Lower Rio Grande Valley, Texas
(1976) Bureau of Economic Geology
This report and the accompanying hand-colored maps (Land and Water Resources, Cameron and Willacy Counties, Texas; Land and Water Resources, Hidalgo County, Texas; and Land Use, Lower Rio Grande Valley, Texas) were prepared initially by the Bureau of Economic Geology, The University of Texas at Austin, as part of a multidisciplinary study of the Lower Rio Grande Valley. The following text is only a portion of the initial report on this study and has been extracted to describe units on the accompanying maps.
Hydrology of Gulf Coast Aquifers, Houston-Galveston Area, Texas
(1977) Kreitler, Charles W.; Guevara, Edgar H.; Granata, G.; McKalips, Dawn G.
Aquifers in the Houston-Galveston area are composed principally of fluvial-deltaic sediments. The Alta Loma Sand is a complexly faulted, high-sand-percent unit that represents a seaward progression of fluvial, delta-plain, and delta-front facies. The Beaumont Formation, overlying the Alta Loma Sand, is a high-mud-percent unit that represents a coastal progression of delta-plain to delta-front facies. Four arbitrarily defined intervals from land surface to 2000 ft indicate the superposition of dip-oriented and strike-oriented high-sand-percent trends. Aquifer geology partly controls short-term and long-term aquifer hydrology. Dip-oriented high-sand-percent trends are optimum locations for ground-water development. Growth faults act as partial hydrologic barriers to ground-water production. Faults between Harris and Galveston Counties have partly isolated the aquifers into two subsystems. In Harris County, groundwater of low dissolved solids is meteoric in origin, whereas in Galveston County, groundwater of low dissolved solids is a mixture of meteoric and saline waters.
Salt Cavern Studies- Regional Map of Salt Thickness in the Midland Basin
(1977) Hovorka, Susan D.
Regional variation in the thickness of the major bedded salt-bearing interval of West Texas, the Salado Formation, provides a screening criterion for separating areas where the salt is heterogeneous, complex, and potentially less stable from areas where salt is more homogeneous. Areas of reduced and variable salt thickness and relatively shallow depths to the top of the salt are identified on the eastern shelf of the Midland Basin in Garza, Borden, Howard, Glasscock, and Reagan counties; along the Pecos River in Crockett, Upton, Crane, and Pecos Counties; and along the western edge of the Central Basin Platform in Ward and Winkler Counties. Reconnaissance data suggest that salt may be locally or regionally actively dissolving from these areas. Salt thinning in areas where the top of salt is relatively deep (> 1500 ft) is noted south of the Matador Arch in Cochran, Hockley, and Lubbock counties, and locally along the eastern edge of the Central Basin Platform in Gaines, Andrews, and Ector Counties. The thinning in these areas is tentatively interpreted as dominantly the result of deposition of thin salt or Permian salt dissolution. In all the areas of thinning, sedimentary patterns suggest that facies changes may also change the quality of the salt (salt purity, water content, bed thickness) over short distances. In other areas within the Midland and Delaware Basins, salt thickness changes are gradual. However, the potential for local areas of salt dissolution, not identified in this regional study (for example, those that may be beneath saline lakes), to impact the suitability of salt in these areas as host strata for cavern development was not investigated.
Depositional Systems, Uranium Occurrence and Postulated Ground Water History of the Triassic Dockum Group, Texas Panhandle-Eastern New Mexico
(1977) McGowen, J. H.; Granata, G.; Seni, Steven J.
Late Triassic (Dockum Group) rocks accumulated in a relict Paleozoic basin defined, in Texas, by the Amarillo Uplift to the north and the Glass Mountains to the south. This basin was reactivated during the Late Paleozoic or Early Mesozoic by tectonic activity that probably was related to the opening of the Gulf of Mexico. The basin subsided, some relict positive elements were uplifted, and sediments began to accumulate in the basin. More than 2,000 feet of terrigenous clastics, derived mostly from older sedimentary rocks, accumulated within the basin. Source areas were in Texas, Oklahoma, and New Mexico; sediment transport was from the south, east, north, and west. The Dockum Group accumulated in a variety of depositional systems including: (1) braided and meandering streams; (2) alluvial fans and fan deltas; (3) distributary-type lacustrine deltas (highly constructive lobate deltas); (4) lacustrine systems including ephemeral and relatively long-lived lakes; and (5) mudflats. Dockum sedimentation was cyclic. The underlying cause of cyclicity was an alternation of humid and arid climate; tectonism most likely was the climatic trigger. During humid climatic conditions, lake level was relatively stable (lake area and depth were maximum). Meandering streams supplied sediment to high-constructive lobate deltas in the central basin area (Texas and New Mexico), whereas braided streams and fan deltas were dominant depositional elements within southern and northern basin areas. Lake area and depth decreased during arid climatic conditions, base level was lowered, valleys were cut into older Dockum deposits, and relatively small fan deltas were constructed along margins of ephemeral lakes. Evaporites, calcretes, silcretes, and soils developed upon floors of ephemeral lakes and on delta platforms. Occurrence of uranium in the Dockum Group has been known for years. An association between depositional facies and uranium occurrence was first documented through research by the Bureau of Economic Geology. Twenty-five distinct depositional facies have been recognized in the Dockum; each of these facies contains uranium. Highest uranium values are in lacustrine facies which developed under arid climatic conditions; however, only a few areas exhibited high values. Channel-lag facies of meanderbelt systems generally exhibit consistently higher uranium values than other depositional facies. Crevasse channel and crevasse splay deposits associated with meandering streams and delta distributaries locally contain carbonized wood, some of which contains uranium. Facies of high-constructive lobate deltas contain uranium; highest values are exhibited by delta front sandstones. Some valley-fill deposits are mineralized; radioactive minerals mostly are within conglomeratic parts of the sequence. Uranium deposits within the Dockum Group are, for the most part, epigenetic and generally occur within sandstone bodies. Four sources of uranium for Dockum mineralization are possible: (1) Triassic volcanics; (2) igneous rocks in Oklahoma; (3) Cretaceous volcanics; and (4) Tertiary volcanics. Although there is a relationship between uranium occurrence and depositional facies, prediction of areas of uranium occurrence is difficult because of a rather complex groundwater history. Groundwater flow was for the most part basinward (down depositional slope) during deposition and shallow burial of the Dockum. Erosion during Jurassic and Early Cretaceous influenced local groundwater flow, which would have been toward erosional lows. Groundwater chemistry was probably affected by marine transgression during the Cretaceous. Following accumulation of Cretaceous sediments, erosion again dominated the area of the Dockum basin; erosion prevailed until sometime during the Pliocene. Pliocene (Ogallala Formation) wet alluvial fan deposits accumulated upon a highly dissected surface underlain in part by Cretaceous rocks, but most of the area was underlain by the Dockum Group. During and subsequent to Pliocene deposition, groundwater flow was to the east in both the Ogallala Formation and the upper part of the Dockum Group. At present, there are two favorable areas for uranium exploration in outcrop: (1) Tule Canyon-Palo Duro Canyon area, and (2) from southern Dickens County southward through Mitchell County. Within the subsurface, a widespread radiometric anomaly occurs at the top of the lowermost progradational sequence; this anomaly is a few hundred to more than 1,000 feet below ground surface. A fourth favorable area for uranium exploration is the uppermost Dockum which has been dissected and is immediately overlain by the volcanic ash-bearing Pliocene Ogallala Formation.
Sampling and Preliminary Analysis and Mapping of Texas Bays and Inner Continental Shelf
(1977) McGowen, J. H.; Morton, Robert A.
In December 1975, the first cruise of the Texas submerged lands research program began aboard the research vessel Faye, with 11 days of marine seismic profiling on the inner continental shelf off Brownsville and southern Laguna Madre, Texas. Since that first cruise, research scientists of the Bureau of Economic Geology have spent many months mapping the Texas shelf aboard the University of Texas research vessel Longhorn, and aboard smaller boats, airboats, and land vehicles in and around the Texas bays from Louisiana to the Rio Grande (Fig. 1). Throughout the program, research personnel of the U.S. Geological Survey, Corpus Christi, Texas, cooperated fully, matched certain funds, and supplied critical equipment and personnel. Consequently, the Texas program was integrated fully with U.S. Geological Survey and Bureau of Land Management studies of the Federal OCS of South Texas.
Evaluating the Potential of East Texas Interior Salt Domes for Isolation of Nuclear Wastes
(1977) Brown, Jr., L. F
At least as early as 1960, the U.S. Atomic Energy Commission was contracting studies of the suitability of salt (halite) as repositories for waste nuclear products. Underground disposal offers the most favorable means of ensuring confinement of a growing volume of nuclear waste products. The chemical and physical properties of salt, either in domes or in bedded layers, have focused principal attention on the potential nature of salt repositories. Bedded salt deposits of various ages occur as strata within numerous sedimentary basins in the United States. In Texas, parts of the Permian Basin, the Palo Duro and Dalhart basins, are currently under investigation to determine waste isolation potential by the Bureau of Economic Geology, The University of Texas at Austin. Texas also contains at least 78 on-land salt domes that are sufficiently shallow to identify by conventional geophysical and drilling/subsurface mapping methods. Of these 78 domes, 20 domes occur within the interior East Texas Basin. Previous workers have considered coastal domes to be unstable and have also rejected about two-thirds of the Texas interior domes for various reasons (to be discussed later). Consequently, using a variety of criteria and data, approximately a half dozen interior Texas salt domes are currently "unrejected" by studies to date. At this time, it is necessary to reassess the earlier studies of East Texas interior domes, review the potential of the domes for nuclear waste isolation, and undertake intensive analysis of selected, high-priority candidate domes. This thorough evaluation must precede any decision concerning the actual use of the domes for nuclear waste disposal. Every conceivable natural factor must be considered and tested if necessary. Principal research effort should be focused very quickly on specific domes. We believe, however, that along with site-specific studies, continuing analysis of regional geohydrologic systems and salt-basin tectonics should be integrated with site-specific evaluations.
Locating Field Confirmation Study Areas for Isolation of Nuclear Waste in the Texas Panhandle
(1977) Galloway, William E.; Gustavson, Thomas C.
Early in 1977, the Bureau of Economic Geology was invited to assemble and evaluate geologic data on several salt-bearing basins within the State as a contribution to the national nuclear repository program. In response to this request, the Bureau, acting as a technical research unit of The University of Texas at Austin and the State of Texas, initiated a long-term program to assemble and interpret all geologic and hydrologic information necessary for the delineation, description, and evaluation of salt-bearing strata and their environments in the Panhandle area. The technical effort has, to date, been divided between two research groups. A basin analysis group has assembled the regional stratigraphic and structural framework of the total basin fill, initiated an evaluation of natural resources, and selected stratigraphic core sites for sampling the salt and associated beds. Two drilling sites have provided nearly 8,000 feet of core material for analysis and testing of the various lithologies overlying and interbedded with salt units. Concurrently, a surface studies group has collected ground and remotely sensed data toward describing surficial processes, including carbonate and evaporate solution, geomorphic evolution, and fracture system development. A newly formed basin geohydrology group will evaluate both shallow and deep circulation of fluids within the basins. This paper is a summary report of progress to date. It reviews principal conclusions and illustrates methodologies utilized and the types of data and displays generated. Several topical reports will be forthcoming as various phases of the study are completed and will discuss in detail various geological aspects of the Palo Duro and Dalhart Basins.
Distribution of Marine Grasses in Southern Laguna Madre
(1977) Chin, John L.
The study area of this report encompasses approximately 80 square miles of lagoon bottom off the Arroyo Colorado River in Southern Laguna Madre, Texas. The climate is semi-arid, as evaporation exceeds precipitation each year. Average monthly rainfall shows a bimodal distribution. Fresh-water runoff from the mainland into the lagoon is essentially negligible. Prevailing winds are from the southeast. The majority of geologic and hydrologic work is done by southeast and south-southeast winds. The daily effect of the tide decreases away from Brazos Santiago Pass. Furthermore, wind tides are the primary force controlling water circulation and inundation of lowlands in the Lower Laguna Madre. Fieldwork was conducted from March through April. Three hundred and eight bay-bottom samples were taken on a one-half mile grid. Field identifications and observations served as the basis for 1977 maps of seagrass distribution and density. Available mapping, from the Texas Parks and Wildlife Department, documented seagrass distribution and density for the years 1961, 1965, 1966, and 1969 to 1973. Five marine spermatophytes occur on the Texas Gulf Coast: Halodule wrightii, Ruppia maritima, Syringodium filiforme, Halophila engelmannii, and Thalassia testudinum. All but Thalassia were encountered in the study area.
Continued Analyses of Surficial Deposits on Texas Submerged Lands
(1978) McGowen, J. H.; Morton, Robert A.
The state-owned submerged lands of Texas are vast. They encompass nearly 6,000 sq. miles (15540 kmÂ²) and extend from Mexico to Louisiana. The area includes the bays, estuaries, and lagoons as well as the inner continental shelf 10.3 miles (16.6 km) seaward of the Gulf shoreline (fig. 1). There are many uncertainties as to the future utilization of the state submerged lands, and we are probably incapable of anticipating all the potential uses for these areas. We can, however, expect multiple and diverse uses related to food production, energy production, recreation, resource extraction, industrial processing, transportation, and the like. Initial planning for many of these activities requires a knowledge of the regional geology, the active geological processes, and the potential environmental impacts of human activities. A comprehensive investigation of the state submerged lands is being conducted to develop a baseline inventory of geological and biological data for future environmental monitoring. The program was designed to provide the basic scientific data necessary to assess and predict the problems and potential impacts resulting from energy, mineral, transportation, recreation, and industrial development along the Texas coast and on the adjacent Federal outer continental shelf. Results of this project will provide Texas with comprehensive natural resources data with which to assess the various development scenarios that can be anticipated by the Texas Coastal Management Program. Support for this comprehensive research project was provided by (1) funding from the Coastal Zone Management Program of the Texas General Land Office to the Bureau of Economic Geology (McGowen and others, 1977a) and (2) substantial financial and logistical contributions made through the joint research program between the U.S. Geological Survey and the Bureau of Economic Geology. Because the same equipment and analytical procedures are being used, data collected for the state submerged lands are compatible with data generated by the U.S. Geological Survey for the South Texas outer continental shelf as part of a study funded by the Bureau of Land Management (Berryhill, 1977). Thus, sedimentological, geochemical, geophysical, and biological data are available for South Texas coastal waters and adjacent continental shelf extending to the shelf break. Such a massive effort would not have been possible without the full cooperation of both research organizations and the pooling of funds, ship time, equipment, and personnel.
Geopressured Geothermal Fairway Evaluation and Test Well Site Location Frio Formation, Texas Gulf Coast
(1978) Bebout, Don G.; Gregory, A. R. (Alvin Ray), 1915-; Loucks, R. G.
Tertiary strata of the Texas Gulf Coast comprise a number of terrigenous depositional wedges, some of which thicken abruptly at their downdip ends as a result of contemporaneous movement of growth faults and underlying salt. The Frio Formation, one of these wedges, has been studied regionally by means of a grid of correlation cross sections aided by micropaleontological control. By means of these sections, the Frio was subdivided into six map units; maps of sandstone distribution within these units delineate principal elongate sandstone trends parallel to the Gulf Coast composed of deltaic, barrier-bar, and strandplain sandstones. These broad regional studies, followed by detailed local investigations, were pursued in order to delineate prospective areas for the production of geopressured geothermal energy. A prospective area must meet the following minimum requirements: reservoir volume of 3 cubic miles, minimum permeability of 20 millidarcys (md), and fluid temperatures of 300Â°F. Several geothermal fairways were identified as a result of this Frio study.

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