Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “The Mountaineer”

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

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,567 records · Page 87Linked to original sources
USGS2010

Den-site characteristics of black bears in Rocky Mountain National Park, Colorado

We compared historic (1985-1992) and contemporary (2003-2006) black bear (Ursus americanus) den locations in Rocky Mountain National Park (RMNP), Colorado, USA, for habitat and physiographic attributes of den sites and used maximum entropy modeling to determine which factors were most influential in predicting den-site locations. We observed variability in the relationship between den locations and distance to trails and elevation over rime. Locations of historic den sites were most associated with slope, elevation, and covertype, whereas contemporary sites were associated with slope, distance to roads, aspect, and canopy height. Although relationships to covariates differed between historic and contemporary periods, preferred den-site characteristics consistently included steep slopes and factors associated with greater snow depth. Distribution of den locations shifted toward areas closer to human developments, indicating little negative influence of this factor on den-site selection by black bears in RMNP.

Journal of Wildlife Management↗
USGS2010

Habitat assessment for giant pandas in the Qinling Mountain region of China

Because habitat loss and fragmentation threaten giant pandas (Ailuropoda melanoleuca), habitat protection and restoration are important conservation measures for this endangered species. However, distribution and value of potential habitat to giant pandas on a regional scale are not fully known. Therefore, we identified and ranked giant panda habitat in Foping Nature Reserve, Guanyinshan Nature Reserve, and adjacent areas in the Qinling Mountains of China. We used Mahalanobis distance and 11 digital habitat layers to develop a multivariate habitat signature associated with 247 surveyed giant panda locations, which we then applied to the study region. We identified approximately 128 km 2 of giant panda habitat in Foping Nature Reserve (43.6% of the reserve) and 49 km 2 in Guanyinshan Nature Reserve (33.6% of the reserve). We defined core habitat areas by incorporating a minimum patch-size criterion (5.5 km 2 ) based on home-range size. Percentage of core habitat area was higher in Foping Nature Reserve (41.8% of the reserve) than Guanyinshan Nature Reserve (26.3% of the reserve). Within the larger analysis region, Foping Nature Reserve contained 32.7% of all core habitat areas we identified, indicating regional importance of the reserve. We observed a negative relationship between distribution of core areas and presence of roads and small villages. Protection of giant panda habitat at lower elevations and improvement of habitat linkages among core habitat areas are important in a regional approach to giant panda conservation.

Qinling Mountains↗
USGS2010

Demographics of an experimentally released population of elk in Great Smoky Mountains National Park

We assessed the potential for reestablishing elk ( Cervus elaphus ) in Great Smoky Mountains National Park (GSMNP), USA, by estimating vital rates of experimentally released animals from 2001 to 2006. Annual survival rates for calves ranged from 0.333 to 1.0 and averaged 0.592. Annual survival for subadult and adult elk (i.e., ≥1 yr of age) ranged from 0.690 to 0.933, depending on age and sex. We used those and other vital rates to model projected population growth and viability using a stochastic individual-based model. The annual growth rate (λ) of the modeled population over a 25-year period averaged 0.996 and declined from 1.059 the first year to 0.990 at year 25. The modeled population failed to attain a positive 25-year mean growth rate in 46.0% of the projections. Poor calf recruitment was an important determinant of low population growth. Predation by black bears ( Ursus americanus ) was the dominant calf mortality factor. Most of the variance of growth projections was due to demographic variation resulting from the small population size ( n = 61). Management actions such as predator control may help increase calf recruitment, but our projections suggest that the GSMNP elk population may be at risk for some time because of high demographic variation.

Great Smoky Mountains National Park↗
USGS2003

Growth and secondary production of aquatic insects along a gradient of Zn contamination in Rocky Mountain streams

Secondary production estimates from several Rocky Mountain streams were used to test hypotheses about the effects of chronic metal contamination on insect populations and ecosystem processes. Quantitative samples of chemistry, habitat, and benthic insects were collected monthly during the ice-free period (May–November) from five 2 nd - to 3 rd -order streams that varied primarily in Zn contamination. Secondary production was estimated for the 19 dominant taxa using increment-summation, size-frequency, and P/B methods. Uncertainty was estimated by bootstrapping estimates of mean abundance, biomass, and cohort production intervals. Secondary production of metal-sensitive Heptageniidae ( Rhithrogena robusta , Cinygmula spp., and Epeorus longimanus ) was lower in lightly to moderately contaminated streams than in reference streams. Experiments were done to determine whether herbivore growth was influenced by food quality in contaminated streams. Growth estimates from field and microcosm experiments revealed that low mayfly production in contaminated streams was caused mostly by reduced population abundances. Production of predatory stoneflies was also lower in contaminated streams than reference streams. Estimates of the trophic basis of production revealed that, although the relative contribution to community production from various food sources was similar among streams, total production attributable to algae and animal prey declined in contaminated streams. Much of the reduction in herbivory in contaminated streams was the result of lower production of heptageniids, especially R. robusta . Assemblage and taxon-specific estimates of secondary production were sensitive to variation in metal contamination and indicated that relatively low metal concentrations may have ecosystem-wide consequences for energy flow.

Journal of the North American Benthological Societ↗
USGS1990

Phytoplankton dynamics in three Rocky Mountain lakes, Colorado, USA

In 1984 and 1985 seasonal changes in phytoplankton were studied in a system of three lakes in Loch Vale, Rocky Mountain National Park, Colorado. Three periods were evident: (1) A spring bloom, during snowmelt, of the planktonic diatom Asterionella formosa , (2) a mid-summer period of minimal algal abundance, and (3) a fall bloom of the blue-green alga Oscillatoria limnetica . Seasonal phytoplankton dynamics in these lakes are controlled partially by the rapid flushing rate during snowmelt and the transport of phytoplankton from the highest lake to the lower lakes by the stream, Icy Brook. During snowmelt, the A. formosa population in the most downstream lake has a net rate of increase of 0.34 d -1 , which is calculated from the flushing rate and from the A. formosa abundance in the inflow from the upstream lake and in the downstream lake. Measurement of photosynthetic rates at different depths during the three periods confirmed the rapid growth of A. formosa during the spring. The decline in A. formosa after snowmelt may be related to grazing by developing zooplankton populations. The possible importance of the seasonal variations in nitrate concentrations were evaluated in situ enrichment experiments. For A. formosa and O. limnetica populations, growth stimulation resulted from 8- or 16-micromolar amendments of calcium nitrate and sulfuric acid, but the reason for this stimulation could not be determined from these experiments.

Colorado↗
USGS1987

Dynamics of Mojave Desert shrub assemblages in the Panamint Mountains, California.

We studied shrub communities in the Panamint Mountains of the Mojave Desert to determine whether vegetational changes after disturbance can be characterized as succession according to modern successional theory. We found, on a variety of disturbed and undisturbed sites, that the rate of change was a function of the type and age of disturbance. Recent debris—flow deposits were colonized by shrub assemblages of different species composition than those on the surrounding, older debris—flow deposits and other geomorphically stable surfaces. Colonization of human—disturbed sites was highly variable, but species compositions were different from the predisturbance species composition. In Grayia—Lycium assemblages, Grayia spinosa reasserted its dominance over colonizers relatively quickly. In Coleogyne assemblages, typically found on older geomorphic surfaces, species composition differences persisted considerably longer, depending on the severity of the initial disturbance. Extremely stable assemblages, dominated by Coleogyne ramosissima, occurred on the oldest, least disturbed surfaces. The variability of species composition among disturbed sites was greater than the variability among undisturbed and geomorphically stable sites, in accord with convergent succession. Models of desert succession should consider several factors: (1) colonization is dependent largely on the severity of disturbances and residual biotic components; (2) the time span for recovery may be longer than past periods of climatic and geomorphic stability; and (3) colonizing species may have considerable range in their life—history strategies.

California↗
USGS1994

Disturbance regime and disturbance interactions in Rocky Mountain subalpine forest

1 The spatial and temporal patterns of fire, snow avalanches and spruce beetle out-breaks were investigated in Marvine Lakes Valley in the Colorado Rocky Mountains in forests of Picea engelmannii , Abies lasiocarpa , Pseudotsuga menziesii and Populus tremuloides . Dates and locations of disturbances were determined by dendrochronological techniques. A geographic information system (GIS) was used to calculate areas affected by the different disturbance agents and to examine the spatial relationships of the different disturbances. 2 In the Marvine Lakes Valley, major disturbance was caused by fire in the 1470s, the 1630s and the 1870s and by spruce beetle outbreak in c. 1716, 1827 and 1949. 3 Since c. 1633, 9% of the Marvine Lakes Valley has been affected by snow avalanches, 38.6% by spruce beetle outbreak and 59.1% by fire. At sites susceptible to avalanches, avalanches occur at a near-annual frequency. The mean return intervals for fire and spruce beetle outbreaks are 202 and 116.5 years, respectively. Turnover times for fire and spruce beetle outbreaks are 521 and 259 years, respectively. 4 Several types of disturbance interaction were identified. For example, large and severe snow avalanches influence the spread of fire. Similarly, following a stand-devastating fire or avalanche, Picea populations will not support a spruce beetle outbreak until individual trees reach a minimum diameter which represents at least 70 years' growth. Thus, recent fires and beetle outbreaks have nonoverlapping distributions.

Journal of Ecology↗
USGS1983

Distribution of corticolous noncrustose lichens on trunks of Rocky Mountain junipers in Boulder County, Colorado.

Nineteen species of noncrustose lichens were found on Juniperus scopulorum bark; 3 species had relatively high cover and frequency values and were characterized as typical lichens of Rocky Mountain junipers: Xanthoria fallax, Phaeophyscia hirsuta and Physcia caesia. Total cover per tree was low (4%) and most species preferred the N and E sides of trunk bases. These distributional trends may reflect gradients of exposure to wind, insolation, and rate of bark exfoliation. -Author Juniperus scopulorum Phaeophyscia hirsuta Physcia caesia Xanthoria fallax.

Colorado↗
USGS2000

The mountain that moved: geologic wonders of the George Washington and Jefferson National Forests

Prehistoric, giant landslides in Montgomery and Craig Counties, Va., in the Blacksburg/Wythe Ranger Districts of the Jefferson National Forest, are the largest known landslides in eastern North America and are among the largest in the world. One of the landslides is more than 3 miles long! The ancient, giant landslides extend for more than 20 miles along the eastern slope of Sinking Creek Mountain. Enormous slabs of rock ranging from about 0.2 to more than 1.5 square miles in size broke loose and slid downslope under the influence of gravity. The movement of some slides may have been slow, but the movement of others was probably sudden and catastrophic.

Virginia↗
USGS1972

Principal facts for gravity stations in the Bearpaw Mountains and vicinity, Montana

Observed gravity values, station locations, terrain corrections, and Bouguer gravity data are provided in tabular form for approximately 500 gravity observations in north-central Montana. These data were used in preparation of -- Peterson, Donald L. and Rambo, William L., 1967, Bouguer gravity anomaly map of the Bearpaw Mountains and vicinity, Montana: U.S. Geol. Survey open-file report.

Montana↗
USGS1970

Remote sensor application studies report, July 1, 1968 to June 30, 1969: Remote sensing reconnaissance, Mill creek area, Arbuckle Mountains, Oklahoma

As part of the U.S. Geological Survey's Remote Sensor Application Studies program, infrared images and several kinds of photographs were obtained on reconnaissance flights over two areas in the Arbuckle Mountains near Mill Creek, Oklahoma. These data were used in a preliminary investigation (1) to determine the diagnostic reflection and emission characteristics of various rock types, and (2) io evaluate the perturbing influence of atmospheric conditions, surface coatings, rock texture, and topography on the observed reflected and emitted energy in the thermal infrared (8-14μ) part of the spectrum

Oklahoma↗
USGS1978

New potassium-argon data on the age of mineralization and metamorphism in the Willow Creek mining district, southern Talkeetna Mountains, Alaska

The now largely abandoned Willow Creek mining district, southern Talkeetna Mountains, Alaska, produced nearly $18,000,000 in gold and minor silver between 1909 and the early 1950's. Mineralized quartz veins, which contain gold and silver along with minor quantities of base metals (in pyrite, galena, chalcopyrite, sphalerite, molybdenite, and arsenopyrite), cut Late Cretaceous and early Tertiary tonalite and quartzmica schist of probable Jurassic age (Ray, 1954; Silberman and others, 1976; Bela Csejtey, Jr., unpub. data, 1978).

Alaska↗
USGS2001

Reconnaissance geology north of the Hoholitna River, Taylor Mountains D-1 1:63,360-scale quadrangle, southwestern Alaska: A section in Geological studies in Alaska by the U.S. Geological Survey, 1999

The lower Paleozoic (Silurian and Ordovician) carbonate stratal succession is divided into six unnamed stratigraphic units in the northern part of the Taylor Mountains D-1 1:63,360-scale quadrangle of southwestern Alaska. Several of these units have previously been recognized in the McGrath and Medfra quadrangles to the northeast in strata of the Nixon Fork subterrane of the Farewell terrane (Decker and others, 1994 ). These rocks occur along the south side of a prominent east-west-trending anticlinoria! axis exposed slightly to the north in the Sleetmute A-2 1:63,360-scale quadrangle. Rocks of the Nixon Fork subterrane are now thought to represent a continental margin sequence rifted from Siberia. The low thermal alteration indices exhibited by the rocks of this area have elicited interest for petroleum exploration. However, low total organic carbon (TOC) values from potential source rocks within this lower Paleozoic succession indicate low petroleum potential.

Alaska↗
USGS1967

Mineral appraisal of the Poker Jim Ridge and Fort Warner areas of the Hart Mountain National Antelope Refuge, Lake County, Oregon

The Poker Jim Ridge and Fort Warner areas, which are candidate areas for inclusion in the National Wilderness Preservation System, are in the Hart Mountain National Antelope Refuge in east-central Lake County, south-central Oregon. The two areas form part of an upraised and tilted fault block--a structural element that is typical of the northern part of the Great Basin province. Rocks in the two areas are principally volcanic in origin. They have been faulted, uplifted, and tilted eastward, the older rocks having been more strongly deformed than the younger ones.

Oregon↗
USGS1961

Manganese deposits in the Drum Mountains, Juab and Millard Counties, Utah

The Drum Mountains are in west-central Utah 30 miles northwest of Delta, between the Sevier Desert on the east and Whirlwind Valley on the west. It is a typically barren desert range comprising a westward-tilted structural unit in which is exposed as much as 9,000 feet of quartzite (Cambrian and Precambrian?) and 3,000 feet of carbonate rocks of Cambrian age. These beds, which strike northward and dip west, are cut by myriad east- to northeast-trending faults with displacements of a few feet to a few thousand feet. Quartz monzonite dikes, pebble dikes, and vein deposits are present locally along the faults. The Cambrian rocks are overlain unconformably by volcanic rocks of probable Tertiary age. Bodies of manganese carbonate ore were formed by replacement of two 20-foot beds of impure dolomite at the base of the sequence of carbonate rocks, along their intersection with certain preore faults. The feeding fissures locally contain veins in which rhodochrosite is associated with base metal sulfides. Downward- moving meteoric water has oxidized the ore bodies to a depth of 100 to 200 feet except where they are sealed off by structural or stratigraphic traps. From 1925 to 1953, 72,462 long tons of manganese ore with an average grade of about 25 percent Mn were shipped.

Utah↗
USGS1992

Text and References To Accompany "Map Showing the Thickness and Character of Quaternary Sediments in the Glaciated United States East of the Rocky Mountains"

A 1:1,000,000-scale map of Quaternary deposits has been compiled for the glaciated area of the United States east of the Rocky Mountains (that is, the area covered by the Laurentide ice sheets). Parts of southern Ontario, areas beneath the Great Lakes, and parts of the submerged eastern seaboard are also included on the map. The map has three components that, together, provide the first regional three-dimensional view of these deposits. These map components are the surface distribution of Quaternary sediments, the total thickness of Quaternary sediments, and the distribution of significant buried Quaternary units. For many areas, this is the first map of Quaternary sediment thickness published at any scale. This report provides supporting information for the map, preliminary interpretations of sediment distribution, and the list of geologic sources used to generate the map. Within the mapped area, there is a particular need for three-dimensional geologic mapping to support decisions on water resources and land use. Approximately 40 percent of the U.S. population resides within the mapped area, which is less than one-quarter the size of the conterminous United States. This map is intended to supplement the more detailed mapping on which it is based and is designed to be a regional planning tool. Through the Pleistocene, large deposits of thick glacial sediment accumulated between certain late Wisconsinan glacial lobes, on bedrock topographic highs, whereas relatively thin deposits generally accumulated in the adjacent bedrock lowlands occupied by drainage and ice lobes. The lithology of the bedrock and its resistance to erosion in part controlled the patterns of ice lobation and the distribution of thick sediment. On a local scale, the spatial relation of these sediment masses to ice lobation has been suggested in places, and a regional correlation may have been assumed. This map provides the first comprehensive, regional view of glacial sediment thickness to permit such a correlation to be assessed.

Bulletin↗
USGS2001

Alteration and mineralization in the eastern part of the Soldier Mountains, Camas County, Idaho

The eastern part of the Soldier Mountains in Camas County, south-central Idaho, is underlain principally by plutonic rocks of Cretaceous and Eocene age that locally have undergone propylitic, potassic, and muscovite-quartz alteration. Muscovite- quartz alteration is Cretaceous in age and is localized along joints and fractures, some of which are filled with quartz. Associated veins have yielded minor amounts of gold. Potassic alteration is probably both Cretaceous and Eocene in age but is weakly developed and limited in extent. Propylitic alteration is Eocene in age and is pronounced around biotite granite plutons. Despite a clear association between plutons of biotite granite and widespread propylitic alteration, mineralization associated with these rocks was minimal. Mineralized areas within more mafic Eocene plutons are characterized by veins and (or) stockworks(?) enriched in copper, molybdenum, and silver, but these areas are restricted in size and have not been productive.

Bulletin↗