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292 records · Page 17Linked to original sources
USGS2007

Mercury in precipitation in Indiana, January 2001–December 2003

Mercury in precipitation was monitored during 2001 through 2003 at four locations in Indiana as part of the National Atmospheric Deposition Program-Mercury Deposition Network (NADP-MDN). Monitoring stations were operated at Roush Lake near Huntington, Clifty Falls State Park near Madison, Monroe County Regional Airport near Bloomington, and Indiana Dunes National Lakeshore near Porter. At these monitoring stations, precipitation amounts were measured and weekly samples were collected for analysis of total mercury and methylmercury by low-level methods. Wet deposition was computed with the total mercury and methylmercury concentrations and the precipitation amounts. In 3 years of weekly samples collected at the four monitoring stations, the volume-weighted total mercury concentration was 11.5 ng/L (nanograms per liter). As a reference for comparison, the total mercury concentration in 47 percent of the samples analyzed was greater than the Indiana water-quality standard for mercury (12 ng/L, protecting aquatic life) and nearly all of the concentrations exceeded the Indiana water-quality standards for mercury in the Great Lakes system (1.8 ng/L, protecting human health, and 1.3 ng/L, protecting wild mammals and birds). The precipitation-weighted concentrations at three of the monitoring stations in Indiana in 2003 were in the top 40 percent of all monitoring stations in the NADP-MDN and the concentration at Indiana Dunes was the eighth highest in the NADP-MDN for 2003. At the four monitoring stations during the study period, the mean weekly total mercury deposition was 243 ng/m 2 (nanograms per square meter) and mean annual total mercury deposition was 12,623 ng/m 2 . The annual mercury deposition at the four monitoring stations in Indiana in 2003 was in the top 40 percent of all monitoring stations in the NADP-MDN and the annual mercury deposition at the Clifty Falls station was the tenth highest in the NADP-MDN for 2003. For the 3-year period, the median methylmercury concentration in weekly samples was 0.058 ng/L with a maximum of 5.77 ng/L. Normalized methylmercury deposition was 2.09 ng/m 2 per inch of precipitation and methylmercury deposition was 0.7 percent of the total mercury deposition. The annual and mean weekly methylmercury deposition was highest at the Roush Lake station. Among the monitoring stations in the NADP-MDN with methylmercury data, methylmercury deposition at the monitoring stations in Indiana appeared to be higher than at eight stations in Wisconsin and Minnesota for that same time period, although methylmercury concentrations in Indiana were similar to or lower than those in Wisconsin and Minnesota. Geographically, the weekly total mercury concentrations at Indiana Dunes and Clifty Falls were statistically higher than concentrations at Bloomington, although a statistical difference in weekly total mercury deposition was not found among the four monitoring stations. Annual mercury emissions from sources in the vicinity of Indiana Dunes and Clifty Falls in 2001 were more than 10 times those at Bloomington, although other factors may help explain the differences in total mercury concentrations, such as the types of mercury emissions, mercury transport from sources outside Indiana, and meteorological conditions. Mercury concentrations and deposition varied at the four monitoring stations during the 3-year period. Total mercury concentrations in weekly samples ranged from 1.54 to 77 ng/L and weekly mercury deposition ranged from 0.8 to 2,456 ng/m 2 . Data from weekly samples exhibited seasonal patterns. Total mercury concentrations and deposition were highest in spring and summer and lowest in winter. Methylmercury concentrations were highest in winter and methylmercury deposition was highest in spring. Annual precipitation at the four monitoring stations was highest in 2003, exceeding the precipitation normals in spring and summer 2003. Annual mercury deposition in 2003 at the Roush Lake, Clifty Falls, and Indiana Dunes was as much as 41 to 67 percent higher in 2003 than in 2001 or in 2002 at those stations. Total mercury deposition that was more than 10 percent of the mean annual deposition (1,262 ng/m 2 ) was recorded in 11 of 551 weekly samples from the study period. These samples contained approximately 3 inches or more of rain and most were collected in spring and summer 2003. The highest deposition (2,456 ng/m 2 in a sample from Roush Lake) was 15.7 percent of the annual deposition at that station and approximately 10 times the mean weekly deposition for Indiana. High deposition recorded in three weekly samples at Clifty Falls contributed 31 percent of the annual deposition at that station in 2003. Weekly samples with high mercury deposition may help to explain the differences in annual mercury deposition among the four monitoring stations in Indiana.

Indiana↗
USGS1968

Geology and ground-water resources of the Deer Lodge Valley, Montana

The Deer Lodge Valley is a basin trending north-south within Powell, Deer Lodge, and Silver Bow Counties in west-central Montana, near the center of the Northern Rocky Mountains physiographic province. It trends northward between a group of relatively low, rounded mountains to the east and the higher, more rugged Flint Creek Range to the west. The Clark Fork and its tributaries drain the valley in a northerly direction. The climate is semiarid and is characterized by long cold winters and short cool summers. Agriculture and ore refining are the principal industries. Both are dependent on large amounts of water. The principal topographic features are a broad lowland, the Clark Fork flood plain, bordered by low fringing terraces that are in turn bordered by broad, high terraces, which slope gently upward to the mountains. The high terraces have been mostly obscured in the south end of the valley by erosion and by recent deposition of great coalescent fans radiating outward frown the mouths of various tributary canyons. The mountains east of the Deer Lodge Valley are formed mostly of Cretaceous sedimentary and volcanic rocks and a great core of Upper Cretaceous to lower Tertiary granitic rocks; those west of the valley are formed of Precambrian to Cretaceous sedimentary rocks and a core of lower Tertiary granitic rocks. Field relationships, gravimetric data, and seismic data indicate that the valley is a deep graben, which formed in early Tertiary time after emplacement of the Boulder and Philipsburg batholiths. During the Tertiary Period the valley was partly filled to a maximum depth of more than 5,500 feet with erosional detritus that came from the surrounding mountains and was interbedded with minor amounts of volcanic ejecta. This material accumulated in a great variety of local environments. Consequently the resultant deposits are of extremely variable lithology in lateral and vertical sequence. The deposits grade from unconsolidated to well-cemented and from clay to boulder-sized aggregates. Throughout most of the area the strata dip gently towards the valley axis, but along the western margins of the valley they dip steeply into the mountains. In late Pliocene or early Pleistocene the Tertiary strata were eroded to a nearly regular valley divide surface. In the western part of the valley the erosion surface was thinly mantled by glacial debris from the Flint Creek Range. Still later, probably during several interglacial intervals, the Clark Fork and its tributaries entrenched themselves in the Tertiary strata to an average depth of about 150 feet. The resultant erosional features were further modified by Wisconsin to Recent glaciofluvial deposition. Three east-west cross .sections and a corrected gravity map were drawn for the valley. They indicate a maximum depth of fill of more than 5,500 feet in the southern part. Depths decrease to the north to approximately 2,300 feet near the town of Deer Lodge. The principal source of ground water in the Deer Lodge Valley is the upper few hundred feet of unconsolidated valley fill. Most of the wells tapping these deposits range in depth from a few feet to 250 feet. Water levels range from somewhat above land surface (in flowing wells) to about 150 feet below. Yields of the wells range from a few gallons per minute to 1,000 gallons per minute. Generally, wells having the highest yields are on the flood plain of the Clark Fork or the coalescent fans of Warm Springs and Mill Creeks. Discharge of ground water by seepage into streams, by evapotranspiration, and by pumping from wells causes a gradual lowering of the water table. Each spring and early summer, seepage of water from irrigation and streams and infiltration of water from snowmelt and precipitation replenish the ground-water reservoir. Seasonal fluctuation of the water table generally is less than 10 feet. The small yearly water table fluctuation indicates that recharge about balances discharge from th

Water Supply Paper↗
USGS1971

Geology of the Stroudsburg quadrangle and Adjacent areas, Pennsylvania--New Jersey

The Stroudsburg area is within the Valley and Ridge and Great Valley physiographic provinces, Northampton and Monroe Counties, Pennsylvania, and Warren County, New Jersey. The northeast-trending subparallel valleys and ridges resulted from erosion of folded heterogeneous sedimentary rocks. These are Middle Ordovician to Middle Devonian in age and are more than 17,000 feet thick. Deposition of a thick flysch sequence (Martinsburg Formation of Ordovician age) accompanied onset of Taconic orogenesis. It was followed by deposition of a thick molasse sequence of Silurian and Early Devonian age (continental and marginal-marine clastics--Shawangunk Formation and Bloomsburg Red Beds--overlain by predominantly marginal-marine and subtidal limestone, dolomite, shale, and sandstone--Poxono Island Formation through Oriskany Group). Basin deepening and gradual shallowing occurred during Esopus through Mahantango deposition, heralding the Acadian clastic wedge exposed north of the Stroudsburg area. Interpretation of sedimentary structures and regional stratigraphic relations suggest that the Silurian and Devonian rocks were deposited in the following environments: A1luviated coastal plain (meandering and braided streams), tidal flats (supratidal and intertidal), barrier zone, and neritic zone (upper and lower). The rock stratigraphic units have been grouped into four lithotectonic units, each having a different style of deformation. Folds produced in these rocks are disharmonic, and it is believed that each rock sequence is set off from units above and below by decollements, or zones of detachment. Movement was northwest into the Appalachian basin, primarily by gravitational sliding. The contact between the Shawangunk Formation of Silurian age and Martinsburg Formation of Ordovician age, is one zone of detachment as well as an angular unconformity. Deformational effects of the Middle to Late Ordovician Taconic orogeny are elusive, but it appears that the folds and most minor structures, including the prominent regional cleavage, were produced during the late Paleozoic Appalachian orogeny and are superimposed upon larger Taconic folds and faults. Field relations and microscopic study suggest that the regional cleavage in the Stroudsburg area is due to laminar flow of pelitic material along cleavage folia accompanied by mechanical reorientation of platy and elongate minerals and neocrystallization of mica, quartz, chlorite, and probably albite. Numerous lines of evidence point to the conclusion that cleavage developed after the rock was indurated and formed at, and Just below, conditions of low-grade metamorphism. Intensity of cleavage development increases to the southeast across the area. Second-generation slip cleavage, also believed to be Appalachian in age, formed by mechanical reorientation of minerals as well as by limited new mineral growth. The topography had a profound effect on the direction of movement of the Wisconsin glacier, as well as the manner of its retreat and the deposits that were formed. Till and stratified drift of Wisconsin age and till of Illinoian(?) age are common in the area. Wisconsin deglaciation occurred by northeastward retreat and by stagnation. A conspicuous terminal moraine marks the limit of Wisconsin ice movement. Lake Sciota was dammed between the retreating ice, the moraine, and the surrounding ridges north of Godfrey Ridge. Several deltas mark ice stand positions during the retreat of the ice. Lake-bottom and kame deposits are locally common in Cherry Valley. South of Kittatinny Mountain, on the other hand, melt water was freely discharged to the south. The wind and water gaps in the Stroudsburg area (including Delaware Water Gap and Wind Gap) are structurally controlled; specifically they are located where folds die out in short distances, where folding is locally more intense, or where resistant rocks dip steeply and have a narrow width of outcrop. This conclusion is contrary to

Open-File Report↗
USGS1960

Areal geology of the Little Cone quadrangle, Colorado

The Little Cone quadrangle includes an area of about 59 square miles in eastern San Miguel County in southwestern Colorado. The quadrangle contains features characteristic of both the Colorado Plateaus physiographic province and the San Juan Mountains, and it has been affected by geologic events and processes of two different geologic environments. The continental sedimentary rocks of the Cutler formation of Permian age are the oldest rocks exposed in the quadrangle. Deposition of the Cutler was followed by a long period of erosion and peneplanation. There is no marked angular discordance between the Cutler and the overlying Dolores formation in the Little Cone quadrangle, but there is in areas some tens of miles east and west of the quadrangle where some crustal warping took place. The continental sedimentary rocks of the Dolores formation of Late Triassic age are red beds that are similar in gross lithology to those of the Cutler. The Dolores formation is subdivided into five general units that persist throughout the quadrangle and for some tens of miles to the north, south, and east. A second long period of erosion followed deposition of the Dolores. The Entrada sandstone of Late Jurassic age overlies the Dolores formation, and is in turn overlain by the Wanakah formation, also of Late Jurassic age. The Wanakah consists of the Pony Express limestone member at the base, the Bilk Creek sandstone'member near the center, and a "marl" member at the top. The Morrison formation, which overlies the Wanakah, consists of the Salt Wash sandstone member in the lower part and the Brushy Basin shale member in the upper part. A period of erosion, probably of relatively short duration, followed deposition of the Brushy Basin member. The Burro Canyon formation of Early Cretaceous age occurs as discontinuous bodies that fill channels cut in the top of the Morrison formation. Deposition of the Burro Canyon formation was followed by another period of erosion, which in turn ended with deposition of the Dakota sandstone of Late Cretaceous age. The Dakota sandstone grades upward into the Mancos shale, also of Late Cretaceous age. The Paleozoic and Mesozoic formations were broadly folded during Laramide time as part of an orogeny of regional extent, and the San Juan Mountains area was uplifted as a broad dome. Extensive erosion followed deformation, and the Cretaceous rocks in the area of the Little Cone quadrangle and the Mesozoic and Paleozoic rocks eastward from the quadrangle were successively bevelled. The Telluride conglomerate of Oligocene(?) age was laid down on this surface. In the Little Cone quadrangle several hundred feet of the Telluride was deposited upon a considerable thickness (probably 3,000 feet or more) of the Mancos shale. At Telluride, about 12 miles east of the quadrangle, the Telluride conglomerate lies upon the Dolores formation. Volcanic rocks of Miocene (?) and Miocene age were deposited widely upon the Telluride conglomerate; at one time they had a thickness of probably 1,000 feet or more in the quadrangle. They have been eroded completely from the quadrangle, but are present in the San Miguel Mountains a few miles to the south and southeast. During the middle Tertiary, probably during the Miocene, the sedimentary rocks were cut by many igneous bodies. Four major rock types are represented; in decreasing order of abundance they are granogabbro, granodidrite, rhyolite(?), and microgabbro. The granogabbro is by far the most abundant, and it forms the Flat Top Peak plug, the Little Cone laccolith, several sills in the Dakota sandstone and the Mancos shale, and a few dikes. The granodiorite forms sills in the Dakota sandstone and the Mancos shale, and the rhyolite(?) forms a single major sill in the Dakota. The microgabbro forms dikes that cut rocks as young as the Mancos shale. Metamorphic effects adjacent to the intrusive bodies generally are restricted to baking that extends only a few feet out into the enclosing rocks; in many places no metamorphic effects are evident. The rocks in the Little Cone quadrangle were displaced along numerous faults in middle Tertiary time, probably after the igneous rocks were injected. All of the faults are normal, and have vertical or very steep dips. In part, the faults form two long and narrow northward- and northwestward-trending grabens that extend into the adjoining Placerville quadrangle to the north. The graben faults form two systems, one trending northward to northwestward, and the other trending northwestward, that are probably contemporaneous. Other faults trend eastward to northeastward; some of these appear to be related to the intrusion of the igneous rocks. At the end of the Tertiary, probably in the early Pleistocene, the general area was again uplifted and subjected to extensive erosion. The Mancos shale was stripped from the northern part of the Little Cone quadrangle, and in this part of the area, the upland surfaces formed on top of the Dakota sandstone were largely controlled by the geologic structure. During the Quaternary a basalt flow was erupted on Specie Mesa on a surface that cuts both the Mancos and the Dakota. The surface preserved beneath the flow has virtually the same position and slope as the adjacent present-day surfaces. Pleistocene deposits consist of (a) high-level or older drift that is unrelated to the present drainage systems and is correlated with the Cerro glacial stage of early Pleistocene age, and (b) younger drift and valley fill within the valleys of the present drainage systems that are correlated with the Durango or Wisconsin glacial stages and may represent both. Recent surficial, landslide, and spring deposits are also present. Within the Little Cone quadrangle and in the Placerville quadrangle to the north and the Gray Head quadrangle to the east, the Entrada sandstone of Late Jurassic age contains vanadium deposits with which are associated large but low-grade amounts of uranium. These deposits form a practically continuous layer about 10 miles long and 1 to 1% miles wide, and possibly a second layer of smaller dimensions. Placer gold deposits in terrace gravel and valley fill of Pleistocene age and in alluvium of Recent age contain the only other ores.

Colorado↗