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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,045 records · Page 58Linked to original sources
USGS2003

Patterns and sources of multidecadal oscillations in drought-sensitive tree-ring records from the central and southern Rocky Mountains

Tree-ring records spanning the past seven centuries from the central and southern Rocky Mountains were studied using wavelet analysis to examine multidecadal (>30-70 yr) patterns of drought variation. Fifteen tree-ring series were grouped into five regional composite chronologies based on shared low-frequency behavior. Strong multidecadal phasing of moisture variation was present in all regions during the late 16th century megadrought. Oscillatory modes in the 30-70 yr domain persisted until the mid-19th century in two regions, and wet-dry cycles were apparently synchronous at some sites until the 1950s drought. The 16th/17th century pattern of severe multidecadal drought followed by decades of wet conditions resembles the 1950s drought and post-1976 wet period. The 16th century megadrought, which may have resulted from coupling of a decadal (???20-30 yr) Pacific cool phase with a multidecadal warm phase in the North Atlantic, marked a substantial reorganization of climate in the Rocky Mountain region.

Geophysical Research Letters↗
USGS2004

Fluctuations in a metapopulation of nesting four-toed salamanders, Hemidactylium scutatum, in the Great Smoky Mountains National Park, USA, 1999-2003

We tested two predictions associated with the hypothesis that certain populations of pond-breeding amphibians are structured into metapopulations using minimum relative abundance estimates of nesting four-toed salamanders (Hemidactylium scutatum Schlegel) from 11 different ponds in the Great Smoky Mountains National Park. Coefficients of variation (CV) for counts at individual ponds ranged from 0.25 to 1.26, and the overall mean CV at all 11 ponds was 0.34. Many pairs of ponds had negative correlations in abundance from 1999-2003, whereas others had various degrees of positive correlation (mean r = 0.29). Thus, nesting population size fluctuated semi-independently among the ponds from year to year, inferring the existence of inter-pond dispersal. The mean number of nesting females at a pond was negatively, but non-significantly, correlated (r = -0.27; P = 0.40; 10 d.f.) to the pond's isolation. Owing to physiological constraints on plethodontid salamander energetics, precipitation during the nesting season (February and March) appeared to play an important role (r = 0.78; P = 0.12; 4 d.f.) in the number of nesting females we observed. Unlike some other plethodontid salamander populations in more fragmented southern Appalachian forest ecosystems, this (meta)population within Great Smoky Mountains National Park does not appear to be declining.

North carolina, Tennessee↗
USGS2007

Discontinuities in stream nutrient uptake below lakes in mountain drainage networks

In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source-waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3- and PO4-3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1-km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape-scale hydrographic and reach-scale hydrogeomorphic, source-water, and biological variables to characterize these landscape positions and analyze relationships to nutrient uptake. Nitrate uptake was undetectable at most lake outlets, whereas PO4-3 uptake was higher at outlets as compared to reference and lake inlet reaches. Patterns in nutrient demand farther downstream were similar to lake outlets with a gradual shift toward reference-reach functionality. Nitrate uptake was most correlated to sediment mobility and channel morphology, whereas PO 4-3 uptake was most correlated to source-water characteristics. The best integrated predictor of these patterns in nutrient demand was % contributing area (the proportion of watershed area not routing through a lake). We estimate that NO3- and PO 4-3 demand returned to 50% of pre-lake conditions within 1-4-km downstream of a small headwater lake and resetting of nutrient demand was slower downstream of a larger lake set lower in a watershed. Full resetting of these nutrient cycling processes was not reached within 20-km downstream, indicating that lakes can alter stream ecosystem functioning at large spatial scales throughout mountain watersheds. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

Limnology and Oceanography↗
USGS2007

Nitrogen saturation in the Rocky Mountains: Linking emissions, deposition, and ecosystem effects using stable isotopes of nitrogen compounds

Elevated levels of atmospheric N deposition are affecting terrestrial and aquatic ecosystems at high elevations in Rocky Mountain National Park and adjacent areas of the Front Range of Colorado. Federal and state agencies are now working together to develop cost-effective means for reducing atmospheric N deposition. A discussion on N saturation covers the need for better understanding of N emission source areas and source types that contribute to N deposition in the Rocky Mountains Front Range of Colorado; reductions in NO emissions that resulted from Clean Air Act Amendments, which caused NO3 deposition to decrease between 1984 and 2003; factors contributing to N deposition, e.g., rapid population growth and energy development; origins of NO3, e.g., as NO emissions from fossil fuel combustion, including stationary sources (e.g. emission from coal combustion in electric generating units), and mobile sources (vehicle emissions); disperse stationary sources from energy resource development, e.g., natural gas production; and the importance of incorporating local source characterization and finer spatial and temporal sampling into future studies, which could provide additional insight into N deposition source attribution. This is an abstract of a paper presented at the 100th Annual Conference and Exhibition of the Air and Waste Management Association (Pittsburgh, PA 6/26-29/2007).

Conference Paper↗
USGS1979

Better utilization of ground water in the Piedmont and mountain region of the southeast

The development of water supplies for domestic consumption, and for those commercial and industrial uses requiring relatively pure water, has followed a pattern in the Piedmont and mountain areas of the southeast similar to that in most other humid areas. The first settlers utilized seepage springs on hillsides. Such springs occur along steep slopes where the water table intersects the land surface. As the population of the region grew, it became increasingly necessary to resort to shallow dug wells for domestic water supplies. Such wells also served as sources of water for the villages that developed, in time, around crossroad taverns. Seepage springs and dug wells are a satisfactory source of water in a virgin environment but are quickly polluted by careless waste-disposal practices. Thus disposal of domestic wastes in shallow pits resulted in epidemics of water-borne diseases as the villages grew into towns. This resulted in the third phase of water-supply development, which consisted of installing water lines and supplying water to homes from town-owned wells. In time, some of these wells became polluted and others failed to supply adequate water for the increasing needs of the larger urban areas. In the fourth phase these areas met their needs by drawing water from nearby streams. By the early years of this century it was possible to make this water palatable and relatively safe as a result of improvement in filtration methods. Streams, of course, have highly variable rates of flow and, as towns grew into small cities, the minimum flow of many streams was not adequate to meet the water-supply needs. This problem was solved in the fifth phase by building dams on the streams. We are still in this phase as we build larger and larger reservoirs to meet our growing water needs. Thus, through five phases of growth in the Piedmont and mountains we have advanced from the point where ground water was the sole source of supply to the point where it is the forgotten resource . For reasons to be explained below, a sixth phase can be foreseen in which ground water and surface water are recognized as parts of the hydrologic system with advantages in their conjunctive development and use.

Piedmont↗
USGS1983

Reconnaissance of ground water in vicinity of Wichita Mountains southwestern Oklahoma

Urbanization and industrial growth have increased demands on water supplies in the vicinity of the Wichita Mountains in southwestern Oklahoma. The principal city, Lawton, uses surface water, supplemented by small quantities of ground water from the Arbuckle Group (Cambrian-Ordovician), for industrial and recreational use. During periods of drought, surface-water supplies in the Wichita Mountains area are not adequate to meet fully the increased water demands. An alternative source of water may be ground water from the Arbuckle Group. Other urban and rural consumers use ground water from Quaternary alluvium, the Rush Springs Formation (Permian), or the Arbuckle Group.

Oklahoma↗
USGS1975

Geology of Porcupine Mountains in Carp River and White Pine Quadrangles, Michigan

The Porcupine Mountains are the eroded remnants of the upper limb of an anticline that is faulted along most of its southern, overturned, limb. The exposed rocks include about 5,000 ft (1,525 m) of middle Keweenawan intermediate to mafic lava flows interbedded with subordinate lithic sedimentary rocks and also include about 3,000 ft (915 m) of overlying middle and upper Keweenawan sedimentary rocks. The sediments are derived from lower Keweenawan and older rocks. The structural relief is at least 8,000 ft (2,440 m) between the crest of the Porcupine Mountains anticline and the trough of the Iron River syncline about 5 mi (8 km) to the south. The reverse fault along the southern, overturned, limb of the anticline has a displacement of about 5,000 ft (1,525 m).

Michigan↗
USGS2013

Epidote from the Zard Mountains, Kharan, Balochistan, Pakistan

The authors received two unusual crystals of epidote from Rock Currier, Jewel Tunnel Imports, in 2012. The mineral specimens were collected at Zard Mountain (Zard Koh), in the central part of the Ruskoh Mountains (Rusk Koh), west of Kharan, Balochistan, Pakistan (written communication, Rock Currier, 2013). The epidote locality was most likely discovered in 2010. These epidote crystals were unusual in both form and composition. The large crystals were flat tabular and pseudohexagonal in shape which is an uncommon crystal form for a monoclinic mineral (fig. 1). Other specimens from the same locality have been described as pseudo-octahedral in shape. The two crystals range in size from 5.5 to 6.5 centimeters (2.2 to 2.6 inches) and are slightly magnetic. The epidote crystals have a core matrix that resembles a weathered igneous rock. Some micro brown- to reddish-titanite crystals were observed under a binocular microscope on the surface and core areas of the crystals (figs. 2 and 3). Other minerals observed in the core areas include feldspar, biotite, and quartz. The crystals display evidence of cluster-growth with points of attachment to other crystals. The epidotes were most likely collected in pockets of a weathered igneous-skarn deposit.

Balochistan, Zard Mountains↗
USGS2010

Gas storage in the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, Oklahoma: how much of a role do the cherts play?

How gas is stored in shale-gas systems is a critical element in characterizing these potentially prolific, low-porosity/permeability reservoirs. An integrated mineralogic, geochemical, and porosity/permeability study is of the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, southern Oklahoma, at locations previously described through detailed stratigraphic and spectral gamma surveys, was undertaken to provide insights into possible mechanisms by which natural gas might be stored in Woodford reservoirs in the adjacent Anadarko Basin. The outcrops in the Arbuckle Mountains are an ideal location to study the Woodford because here the formation is immature or marginally mature for oil generation (Comer and Hinch, 1987; Lewan, 1987), so deep burial and thermal maturation are much less pronounced than is the case for the Woodford in the basin, and as such the samples we studied are not overprinted by possible alterations resulting from deep burial and heating.

Conference Paper↗
USGS2013

Modeling mountain pine beetle disturbance in Glacier National Park using multiple lines of evidence

Temperate forest ecosystems are subject to various disturbances which contribute to ecological legacies that can have profound effects on the structure of the ecosystem. Impacts of disturbance can vary widely in extent, duration and severity over space and time. Given that global climate change is expected to increase rates of forest disturbance, an understanding of these events are critical in the interpretation of contemporary forest patterns and those of the near future. We seek to understand the impact of the 1970s mountain pine beetle outbreak on the landscape of Glacier National Park and investigate any connection between this event and subsequent decades of extensive wildfire. The lack of spatially explicit data on the mountain pine beetle disturbance represents a major data gap and inhibits our ability to test for correlations between outbreak severity and fire severity. To overcome this challenge, we utilized multiple lines of evidence to model forest canopy mortality as a proxy for outbreak severity. We used historical aerial and landscape photos, reports, aerial survey data, a six year collection of Landsat imagery and abiotic data in combination with regression analysis. The use of remotely sensed data is critical in large areas where subsequent disturbance (fire) has erased some of the evidence from the landscape. Results indicate that this method is successful in capturing the spatial heterogeneity of the outbreak in a topographically complex landscape. Furthermore, this study provides an example on the use of existing data to reduce levels of uncertainty associated with an historic disturbance.

Conference Paper↗
USGS2011

Active mountain building and the distribution of core Maxillariinae species in tropical Mexico and Central America

The observation that southeastern Central America is a hotspot for orchid diversity has long been known and confirmed by recent systematic studies and checklists. An analysis of the geographic and elevation distribution demonstrates that the most widespread species of “core” Maxillariinae are all adapted to life near sea level, whereas the most narrowly endemic species are largely distributed in wet highland environments. Drier, hotter lowland gaps exist between these cordilleras and evidently restrict the dispersal of the species adapted to wetter, cooler conditions. Among the recent generic realignments of “core” Maxillariinae based on molecular phylogenetics, the Camaridium clade is easily the most prominent genus in Central America and is largely restricted to the highlands of Costa Rica and Panama, indicating that this region is the ancestral home of this genus and that its dispersal limits are drier, lowland cordilleran gaps. The mountains of Costa Rica and Panama are among the geologically youngest topographic features in the Neotropics, reflecting the complex and dynamic interactions of numerous tectonic plates. From consideration of the available geological evidence, I conclude that the rapid growth of the mountain ranges in Costa Rica and Panama during the late Cenozoic times created, in turn, very rapid ranges in ecological life zones and geographic isolation in that part of the isthmus. Thus, I suggest that these recent geologic events were the primary drivers for accelerated orchid evolution in southeastern Central America.

Central America↗
USGS1974

Distribution and occurrence of rare earths in the thorium veins on Hall Mountain, Idaho

Rare earths, although equal to or more abundant than thorium in many thorium veins, are much less abundant than thorium in the veins on Hall Mountain, Idaho. Total rare-earth content of these veins ranges from 0.00111 to 0.197 percent in 12 samples from 10 veins; the thoria (ThO 2 ) content, from 0.011 to 5.84 percent. The rare-earth oxide to thoria ratios range from 0.0019 to 3.22. Only two samples contained more rare earths than thorium, and these two samples came from veins related to a fault near the base of a thick sill; the others came from veins near the top of the same sill. The relative amounts of the individual lanthanides are remarkably similar in the Hall Mountain veins, although cerium, gadolinium, or dysprosium are the most abundant in different samples. These veins differ in lanthanide distribution both from the Earth's crust and from the thorium veins of the Lemhi Pass district, Idaho and Montana, in that they contain chiefly yttrium-group rare earths. Most of the rare earths occur in thorite, whose atomic structure will accommodate wide-ranging proportions of the rare earths. Cenosite, one of the few minerals with a high content of the yttrium group of rare earths, was found in one vein.

Idaho↗
USGS2015

Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA USA

This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

California↗
USGS2015

Complex interactions between global change drivers influence mountain forest and slpine GHG sequestration and stream chemistry

Many mountain ecosystems are experiencing coincident increases in temperature, levels of atmospheric carbon dioxide (CO2) and atmospheric nitrogen (N) deposition. All are important controls on rates of plant growth, soil microbial activity, nutrient cycling, and stream N export. It is difficult for experimental studies to explore ecosystem responses to more than one or two treatments at plot, let alone catchment, scale. One might expect, however, ecosystems to respond differently to the combined global change drivers than to climate, CO2, or N alone. We explored this question for nine mountain catchments over the period 1980- 2075 with a simulation model.

Conference Paper↗
USGS1978

Age and composition of igneous rocks, Edna Mountain quadrangle, Humboldt County, Nevada

Six pulses of igneous activity ranging in age from Jurassic to Pliocene have been identified in the Edna Mountain quadrangle, Humboldt County, Nev. Porphyritic syenite am! quartz monzonite of Jurassic age (146-164 million years) at Buffalo Mountain are highly potassic through a wide range in SiO 2 content from olivine-bearing syenite to quartz-rich monzonite, and their composition contrasts sharply with plutons elsewhere in north-central Nevada. Granodiorite and quartz monzonite plutons of Cretaceous age (88- 106 m.y.) are chemically and mineralogically similar to other calc-alkaline plutons in north-central Nevada. Four episodes of Tertiary volcanism include rhyolite ashflow tuffs and slightly younger andesitic basalt flows and tuffs of Oligocene age, rhyolite vitrophyre of late Miocene age, and olivine basalt flows of Pliocene age. Their age and mineralogical and chemical compositions are similar to other Tertiary volcanic rocks in north-central Nevada.

Nevada↗
USGS1975

Cylindrical jointing in mafic dikes, central Beartooth Mountains, Montana

Cylindrical joints are well displayed in two Precambrian mafic dikes that cut granitic gneiss in the central Beartooth Mountains, Mont. The dikes are vertical and about 23 m (75 ft) and 23 to 46 m (75-150 ft) thick, respectively. The cylindrical joints are perpendicular to the dike walls, and the cylinders defined by the joints are as much as 5 m (16 ft) in diameter. No petrographic, textural, or other features related to or possibly responsible for the joints are recognized. The dikes are chemically and petrographically similar to quartz dolerite dikes found throughout the Beartooth Mountains. Some of these dikes show typical polygonal columnar joints; a few others have cylindrical jointing, but in most dikes neither kind of jointing was observed. The orientation of the cylindrical joints normal to the walls of the dikes indicates that they probably formed by thermal contraction during post-crystallization cooling of the dikes and are thus genetically related to the much more common polygonal jointing. However, the model proposed to explain the cylindrical joints suggests that their origin is partly dependent on the geometric relation between the orientation of the dikes and that of the predike fracture pattern in the host rock.

Montana, Wyoming↗
USGS2015

Draft comprehensive conservation plan and environmental impact statement-Rocky Mountain Arsenal National Wildlife Refuge

The Rocky Mountain Arsenal National Wildlife Refuge Complex, consisting of some of the newer properties in the National Wildlife Refuge System, is a work in progress. Offering unique assets to surrounding communities, these lands promise to become some of the premier urban wildlife refuges in the country. At the heart of the refuge complex is the Rocky Mountain Arsenal National Wildlife Refuge: 16,000 acres of shortgrass and mixed-grass prairie that is home to bison, bald eagles, migratory songbirds, prairie dogs, and much more—all within the Denver Metropolitan area. This comprehensive conservation plan will be the first in the country designed to begin implementing the Refuge System’s new Urban Refuge Initiative. To accomplish this, we analyzed a wide range of options on how best to support up to one million visitors per year without compromising our principal purposes to protect and preserve fish and wildlife and their habitats. We are fortunate to have inherited a great deal of infrastructure from the U.S. Army, but we are also constrained by the current condition and layout of these facilities. Some of this infrastructure may be acting as barriers to the public—a condition inconsistent with the purposes of the refuge. Accordingly, we have developed a goal to increase and improve suitable access to the refuge, develop sustainable transportation options, and provide more connections among the units of the refuge complex. This increased access will enable people from all walks of life to visit the refuge. The vision we have developed for the refuge complex calls for the restoration of the refuge’s historical habitats, and the reconnection of people with the natural lands of the refuge and of the region at large using a network consisting of multimodal trails, a far-reaching light-rail system, and the Denver International Airport. This refuge is well positioned to leverage and catalyze early investments to create world-class wildlife habitat and a conservation education facility in the heart of a rapidly growing urban metropolis. So positioned, the refuge represents the ideal intersection of nature and education to transmit the message of conservation, outdoor recreation, and stewardship to future generations. Toward this end, collaboration is essential to the refuge’s future success. We will continue to foster and improve our strong public and private partnerships in the surrounding communities. These partnerships will enable us to act quickly and effectively as we invest in education and outreach efforts to fulfill our potential as a conservation catalyst in neighboring communities, the larger Intermountain West, and the world.

Report↗