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Electron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most...

Extending nearly 400 km from Sabine Pass on the Texas-Louisiana border east to the Chandeleur Islands, the Louisiana coastal zone (Fig. 11.1) along the north-central Gulf of Mexico is the southern terminus of the largest drainage basin in North America (>3.3 million km2), which includes the Mississippi River delta plain...

Streamflow-characteristic estimation methods for unregulated rivers and streams of Tennessee were developed by the U.S. Geological Survey in cooperation with the Tennessee Department of Environment and Conservation. Streamflow estimates are provided for 1,224 stream sites. Streamflow characteristics include the 7-consecutive-day, 10-year recurrence-interval low flow, the 30-consecutive-day, 5-year recurrence-interval low flow,...

Federally endangered Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were once abundant throughout their range but populations have declined; they have been extirpated from several lakes, and may no longer reproduce in others. Poor recruitment into the adult spawning populations is one of several reasons cited for...

A study was conducted by the U.S Geological Survey in cooperation with the Arkansas State Highway and Transportation Department to characterize the source and hydrogeologic conditions responsible for thermal water in a domestic well 5.5 miles east of Hot Springs National Park, Hot Springs, Arkansas, and to determine the degree...

Most probabilistic seismic-hazard assessments require an estimate of Mmax, the magnitude (M) of the largest earthquake that is thought possible within a specified area. In seismically active areas such as some plate boundaries, large earthquakes occur frequently enough that Mmax might have been observed directly during the historical period. In...

Upscaling the spatial and temporal changes of carbon stocks and fluxes from sites to regions is challenging owing to the spatial and temporal variances and covariance of driving variables and the uncertainties in both the model and the input data. Although various modeling approaches have been developed to facilitate the...

This report provides results of a rapid assessment of biological carbon stocks and forest biomass carbon sequestration capacity in the conterminous United States. Maps available from the U.S. Department of Agriculture are used to calculate estimates of current organic carbon storage in soils (73 petagrams of carbon, or PgC) and...

The Inyo Mountains are located in east-central California between Owens Valley on the west and Saline Valley on the east. This map encompasses the southernmost part of the Inyo Mountains and vicinity, which is centered on the high plateau of Conglomerate Mesa and extends from Owens Valley on the west...

Reconstructions of Phanerozoic tectonic plates can be closely constrained by lithologic correlations across conjugate margins by paleontologic information, by correlation of orogenic belts, by paleomagnetic location of continents, and by ocean floor magmatic stripes. In contrast, Proterozoic reconstructions are hindered by the lack of some of these tools or the...

Under an initiative started by Thomas G. Hildenbrand of the U.S. Geological Survey, we have improved the long-wavelength (50-2,500 km) content of the regional magnetic anomaly compilation for the conterminous United States by utilizing a nearly homogeneous set of National Uranium Resource Evaluation (NURE) magnetic surveys flown from 1975 to...

The Wilcox Group of Eocene and Paleocene age is located throughout most of southern and eastern Arkansas. The Wilcox Group in southern Arkansas is undifferentiated, while in northeastern Arkansas, the Wilcox Group is subdivided into three units: Flour Island, Fort Pillow Sand, and Old Breastworks Formation. The Wilcox Group crops...

Entrainment of sediment by flowing water affects topography, habitat suitability, and nutrient cycling in vegetated floodplains and wetlands, impacting ecosystem evolution and the success of restoration projects. Nonetheless, restoration managers lack simple decision-support tools for predicting shear stresses and sediment redistribution potential in different vegetation communities. Using a field-validated numerical...

With increasing demands for reliable water supplies and availability estimates, groundwater flow models often are developed to enhance understanding of surface-water and groundwater systems. Specific hydraulic variables must be known or calibrated for the groundwater-flow model to accurately simulate current or future conditions. Surface geophysical surveys, along with selected test-hole...

This geologic map, approximately coincident with the east half of the Seattle North 7.5 x 15’ quadrangle (herein, informally called the “Seattle NE map”), covers nearly half of the City of Seattle and reaches from Lake Washington across to the Puget Sound shoreline. Land uses are mainly residential, but extensive...

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC) in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference...

This report presents the results of a study by the U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, to analyze and compare hydrologic and water-quality characteristics of tallgrass prairie and agricultural basins located within the historical distribution of tallgrass prairie in Missouri and Kansas. Streamflow and...

Oxygen isotopes measured on Late Ordovician conodonts from Minnesota and Kentucky (United States) were studied to reconstruct the paleotemperature history during late Sandbian to Katian (Mohawkian–Cincinnatian) time. This time interval was characterized by intense volcanism, as shown by the prominent Deicke, Millbrig, and other K-bentonite beds. A prominent carbon isotope...

Despite persistent and widespread declines of grassland birds in North America, few studies have assessed differences between native grasslands and seeded monocultures as songbird habitat. In the Great Plains, many fields enrolled in the Conservation Reserve Program have been seeded to Old World bluestems (OWB), but there is evidence...

The Saddle Mountain fault, first recognized in the early 1970s, is now well mapped in the Hoodsport area, southeastern Olympic Peninsula (northwestern United States), on the basis of light detection and ranging (LIDAR) surveys, aerial photography, and trench excavations. Drowned trees and trench excavations...

This report was prepared by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Agriculture (PDA) as part of the Pennsylvania Pesticides and Ground Water Strategy (PPGWS). Monitoring data and extensive quality-assurance data on the occurrence of pesticides in ground water during 2003–07 are presented and evaluated;...

Hurricane Katrina made landfall with the northern Gulf Coast on August 29, 2005, as one of the strongest hurricanes on record. The storm damage incurred in Louisiana included a number of levee failures that led to the inundation of approximately 85 percent of the metropolitan New Orleans area. Whereas extreme...

The Weaverville 15' quadrangle spans parts of five generally north-northwest-trending accreted terranes. From east to west, these are the Eastern Klamath, Central Metamorphic, North Fork, Eastern Hayfork, and Western Hayfork terranes. The Eastern Klamath terrane was thrust westward over the Central Metamorphic terrane during early Paleozoic (Devonian?) time and, in...

The city of Rapid City and other water users in the Rapid City area obtain water supplies from the Minnelusa and Madison aquifers, which are contained in the Minnelusa and Madison hydrogeologic units. A numerical groundwater-flow model of the Minnelusa and Madison hydrogeologic units in the Rapid City area was...

Volcanogenic massive sulfide (VMS) deposits are very significant current and historical resources of Cu-Pb-Zn-Au-Ag, are active exploration targets in several areas of the United States and potentially have significant environmental effects. This new USGS VMS deposit model provides a comprehensive review of deposit occurrence and ore genesis, and fully integrates...