The extent and thickness of Jurassic strata in Alabama and Florida were mapped as part of a U.S. Geological Survey regional geohydrologic study. Rocks equivalent to the Werner, Louann, Norphlet, Smackover, Haynesville, and Cotton Valley sequences of Mississippi and Arkansas have been recognized and, except for the Werner equivalent, are herein extended into panhandle Florida. The predominantly fluvial Jurassic sequence in Alabama and Florida was interrupted at least twice by barred-basin conditions that resulted in the deposition of extensive evaporite deposits, and at least once, during deposition of the Smackover Formation, by a major marine transgression. The updip limits and isopach map trends of the Jurassic units mapped appear to have been controlled by a major nort west-trending, right-lateral wrench fault--the dominant master shear in a regional wrench-fault system active throughout Jurassic time.
Introduction Achieving widespread knowledge of HIV-positive status is a crucial step to reaching universal ART coverage, population level viral suppression, and ultimately epidemic control. We implemented a multi-modality HIV testing approach to identify 90% or greater of HIV-positive persons in the Botswana Combination Prevention Project (BCPP) intervention communities. Methods BCPP is a cluster-randomized trial designed to evaluate the impact of combination prevention interventions on HIV incidence in 30 communities in Botswana. Community case finding and HIV testing that included home and targeted mobile testing were implemented in the 15 intervention communities. We described processes for identifying HIV-positive persons, uptake of HIV testing by age, gender and venue, characteristics of persons newly diagnosed through BCPP, and coverage of knowledge of status reached at the end of study. Results Of the 61,655 eligible adults assessed in home or mobile settings, 13,328 HIV-positive individuals, or 93% of the estimated 14,270 positive people in the communities were identified through BCPP. Knowledge of status increased by 25% over the course of the study with the greatest increases seen among men (37%) as compared to women (19%) and among youth aged 16–24 (77%) as compared to older age groups (21%). Although more men were tested through mobile than through home-based testing, higher rates of newly diagnosed HIV-positive men were found through home than mobile testing. Conclusions Even when HIV testing coverage is high, additional gains can be made using a multi-modality HIV testing strategy to reach different sub-populations who are being missed by non-targeted program activities. Men and youth can be reached and will engage in community testing when services are brought to places they access routinely.
The Tertiary limestone aquifer system of the southeastern United States is a thick sequence of carbonate rocks that vary in age and that are hydraulically connected in varying degrees. The aquifer system consists, in large part, of two major permeable zones separated by a less-permeable unit. A map is presented that shows the altitude and configuration of the base of the upper permeable zone of the system; and the age and lithology of the different low permeability materials that mark the base are delineated and briefly described. Several types of geological structures that affect the configuration of the base of the upper permeable zone may be readily recognized. (USGS)
Discusses hydrogeology from the geological perspective. After describing the major features of 28 hydrogeologic regions of North America, the volume devotes eight chapters to discussion of the comparative hydrogeology of kinds of different bedrock regimes and surficial deposits; seven chapters to geologic processes including karstification, diagenesis, tectonics, ore deposits, and hydrocarbon migration intimately involved with ground water; and two concluding chapters to look at future scientific and societal problems related to ground water.
ABSTRACT Study of cores from a U.S. Geological Survey test well near Polk City indicates that the Avon Park-Lake City (Claibornian) and Oldsmar (Sabinian) Formations, which comprise most of the Floridan aquifer in central Florida, can be divided into six microfacies: foraminiferal mudstone; foraminiferal wackestone-packstone; foraminiferal grainstone; nodular anhydrite; laminated dolomicrite; and replacement dolomite. Dolomite containing variable amounts of nodular anhydrite forms more than 90 percent of the Avon Park-Lake City interval, whereas the Oldsmar is chiefly limestone. The depositional model inferred for these units is a broad, shallow-water marine platform with environments ranging from supratidal-sabkha to shallow-water shelf. Diagenetic pathways vary with rock type, but generally include: (1) marine phreatic -- grain micritization, and radially fibrous cementation within foraminiferal tests; (2) meteoric vadose -- minor leaching of aragonitic grains; and (3) meteroic phreatic -- neomorphism of unstable grains, dissolution of aragonitic allochems, formation of isopachous equant calcite cement and coarse spar in grainstones, and syntaxial calcite overgrowths on echinoderms. Several episodes of dolomite formation are recognized. Laminated dolomicrite formed syngenetically in a supratidalsabkha environment. Crystalline dolomite with nodular anhydrite formed early by replacement of limestone through reflux of dense, Mg-rich brines. Replacement dolomite not associated with evaporites and containing limpid crystals probably formed later by a mixed-water process in the subsurface environment. Late diagenetic processes affecting crystalline dolomites include hydration of anyhdrite to gypsum, partial dissolution of gypsum, alteration of gypsum to calcite (minor), and dissolution of calcian dolomite cores in stoichiometric crystals. Crystalline dolomite and grainstone are the only rock types that have high enough porosities and permeabilities to provide significant yields of water. Medium and finely crystalline dolomites show best values of porosity and permeability because they have high percentages of intercrystal and moldic pores that are well connected. Filling of pores by anhydrite or gypsum can significantly reduce porosity and permeability.
Abstract The horizontal directional drilling (HDD) technology was successfully used in a fracture‐controlled sandstone matrix to intercept a gasoline plume and create a 150‐foot‐long hydrodynamic barrier preventing seepage of gasoline and contaminated ground water into a salmon‐bearing stream within a public park. A 36‐foot‐deep vertical recovery well (VW) intercepts the central low point of the 420‐foot‐long HDD borehole to pump recovered fluids. Contaminant seepage into the creek ceased within hours of starting up the HDD/VW interceptor system in August 1999. Approximately 325 gallons of gasoline and 2 million gallons of contaminated ground water have been recovered to date.
