The molluscan fauna of the Alum Bluff group of Florida, Part III, Lucinacea, Leptonacea, Cardiacea
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No abstract available.
The relation of hydrologic setting and temporal variability in hydrology to nutrient content and geochemical characteristics of a group of prairie wetlands and adjacent ground water was studied during the period 1979-82. Although data were collected from many wetlands and wells at the study site, emphasis in this report primarily is on four wetlands two seasonal and two semipermanent and four wells contiguous to them along a hydrologic section. The seasonal wetlands, T8 and T3, contained water only for a few weeks to months after filling in spring and early summer; both were completely dry by August. The semipermanent wetlands, PI and P8, contained water throughout each year and were ice covered in winter. One wetland, T8, recharges ground water. Wetlands PI and P8 are in areas of ground-water discharge. None of the wetlands received water by channelized surface-water inlets. Only wetland P8 had a channelized surface-water outlet. Ground-water-level data showed that high points of the water table did not always occur beneath land-surface highs. Reversals of ground-water flow occurred occasionally between two of the wetlands, T3 and PI. Significant differences existed in the chemical composition of the wetlands based on their hydrologic setting. In general, the dominant cation and anion in the wetlands were potassium and bicarbonate in wetland T8, calcium and sulfate in wetland T3, magnesium and sulfate in wetland PI, and magnesium and bicarbonate in wetland P8. Significant seasonal differences existed in the water chemistry of the wetlands in ground-water discharge areas. Water in three of the wetlands, T3, Pi, and P8, was most dilute while they filled in spring after icemelt. Concentration increased during the open-water period, and two of the wetlands, PI and P8, became most concentrated under ice cover. Concentrations of total phosphorus and total nitrogen were greatest in wetlands in areas of ground-water recharge and least in wetlands in areas of ground-water discharge. Differences in the chemistry of water from wells in the adjacent ground water resulted primarily from the positions of the wells in the ground-water flow system. The chemical type of water from well 12, which was located in a ground-water recharge area, was calcium sodium bicarbonate. Water from well 4, located downgradient from wetland T8, and from well 16, located downgradient from wetland PI, typically was a calcium sulfate type. Water from well 13, located between wetlands T3 and PI in an area of changing ground-water flow directions, was a magnesium sulfate type. Data from this study show that an understanding of hydrologic conditions is important in the interpretation of the water chemistry of wetlands in the study area.
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No abstract available.
A catastrophic rainstorm in central California on January 3-5,1982, dropped as much as half the mean annual precipitation within a period of about 32 hours, triggering landslides and floods throughout 10 counties in the vicinity of the San Francisco Bay. More than 18,000 of the slides induced by the storm transformed into debris flows that swept down hillslopes or drainages with little warning. Debris flows damaged at least 100 homes, killed 14 residents, and carried a 15th victim into a creek. Shortly after rainfall ceased, more than 459,000 m3 of earth and rock slid from a mountainside above the community of Love Creek in Santa Cruz County, burying 10 people in their homes. Throughout the bay region, thousands of people vacated homes in hazardous areas, entire communities were isolated as roads were blocked, public water systems were destroyed, and power and telephone services were disrupted. Altogether, the storm damaged 6,300 homes, 1,500 businesses, and tens of kilometers of roads, bridges, and communication lines. Preliminary rough estimates of total storm damage, compiled for emergency purposes within 2 weeks of the storm, exceeded $280 million. Carefully documented direct costs from landslides exceeded $66 million; total costs from landslides certainly were greater and probably constituted a much larger proportion of the total storm damage than suggested by these disparate figures. Landslides accounted for 25 of the 33 deaths attributed to the storm.
No abstract available.
No abstract available.
PART 1: Stratigraphic and sedimentological analysis of sedimentary sequences from the Wallowa terrane of northeastern Oregon has provided a unique insight into the paleogeography and depositional history of the terrane, as well as establishing important constraints on its tectonic evolution and accretionary history. Its Late Triassic history is considered here by examining the two most important sedimentary units in the Wallowa terrane-the Martin Bridge Limestone and the Hurwal Formation. Conformably overlying epiclastic volcanic rocks of the Seven Devils Group, the Martin Bridge Limestone comprises shallow-water platform carbonate rocks and deeper water, off-platform slope and basin facies. Regional stratigraphic and tectonic relations suggest that the Martin Bridge was deposited in a narrow, carbonate-dominated (forearc?) basin during a lull in volcanic activity. The northern Wallowa platform was a narrow, rimmed shelf delineated by carbonate sand shoals. Interior parts of the shelf were characterized by supratidal to shallow subtidal carbonates and evaporites, which were deposited in a restricted basin. In the southern Wallowa Mountains, lithofacies of the Martin Bridge are primarily carbonate turbidites and debris flow deposits, which accumulated on a carbonate slope apron adjacent to the northern Wallowa rimmed shelf from which they were derived. Drowning of the platform in the latest Triassic, coupled with a renewed influx of volcanically derived sediments, resulted in the progradation of fine-grained turbidites of the Hurwal Formation over the carbonate platform. Within the Hurwal, Norian conglomerates of the Excelsior Gulch unit contain exotic clasts of radiolarian chert, which were probably derived from the Bakei terrane. Such a provenance provides evidence of a tectonic link between the Baker and Wallowa terranes as early as the Late Triassic, and offers support for the theory that both terranes were part of a more extensive and complex Blue Mountains island-arc terrane. PART 2: Mesozoic rocks exposed along the Snake River in the northern Wallowa terrane represent a volcanic island and its associated sedimentary basins within the Blue Mountains island arc of Washington, Oregon, and Idaho. In the northern part of the Wallowa terrane, rock units include the Wild Sheep Creek, Doyle Creek, and Coon Hollow Formations, the (informal) Imnaha intrusion, and the (informal) Dry Creek stock. The volcanic rocks of the Ladinian to Karnian Wild Sheep Creek Formation show two stages of evolution-an early dacitic phase Gower volcanic faciesY and a late mafic phase (upper volcanic facies). The two volcanic facies are separated by eruption-generated turbidites of siliceous argillites and arkosic arenites (argillitesandstone facies). The two magmatic phases of the Wild Sheep Creek Formation may be recorded by the compositional zoning from older quartz diorite and diorite to younger gabbro in the Imnaha intrusion. Although the Late Triassic Imnaha intrusion is in fault contact with the Wild Sheep Creek Formation, it may be a subduction-related pluton and was the likely magma source for the Wild Sheep Creek Formation. Interbedded with the upper volcanic facies are eruption-generated turbidite and debris flow deposits (sandstone-breccia facies) and thick carbonate units (limestone facies). The limestone facies consists of two marker units, which may represent carbonate platform environments. Clast imbrication, fossil orientation, and cross-stratification in the Wild Sheep Creek Formation indicate a shoaling to subaerial volcanic island to the south and southeast; sediment was transported to the north and northwest. The Karnian Doyle Creek Formation consists largely of epiclastic conglomerate, sandstone, and shale that were deposited in welloxygenated basins. Vitric tuffs interbedded with these sediments suggest shallow or subaerial pyroclastic eruptions. Quartz diorite clasts in this formation may indicate uplift
The copper district of Keweenaw Point, in the northern peninsula of Michigan, is the second largest producer of copper in the world. The output of the district since 1845 has been more than 7,500,000,000 pounds and showed a rather steady and consistent increase from the beginning of production to the end of the World War in 1918, since which there has been a marked decrease.
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