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At least 775 records · Page 43Linked to original sources
USGS2006

Role of multidecadal climate variability in a range extension of pinyon pine

Evidence from woodrat middens and tree rings at Dutch John Mountain (DJM) in northeastern Utah reveal spatiotemporal patterns of pinyon pine ( Pinus edulis Engelm.) colonization and expansion in the past millennium. The DJM population, a northern outpost of pinyon, was established by long-distance dispersal (~40 km). Growth of this isolate was markedly episodic and tracked multidecadal variability in precipitation. Initial colonization occurred by AD 1246, but expansion was forestalled by catastrophic drought (1250–1288), which we speculate produced extensive mortality of Utah Juniper ( Juniperus osteosperma (Torr.) Little), the dominant tree at DJM for the previous ~8700 years. Pinyon then quickly replaced juniper across DJM during a few wet decades (1330–1339 and 1368–1377). Such alternating decadal-scale droughts and pluvial events play a key role in structuring plant communities at the landscape to regional level. These decadal-length precipitation anomalies tend to be regionally coherent and can synchronize physical and biological processes across large areas. Vegetation forecast models must incorporate these temporal and geographic aspects of climate variability to accurately predict the effects of future climate change.

Utah↗
USGS2011

Calcite growth-rate inhibition by fulvic acids isolated from Big Soda Lake, Nevada, USA, the Suwannee River, Georgia, USA and by polycarboxylic acids

Calcite crystallization rates are characterized using a constant solution composition at 25°C, pH=8.5, and calcite supersaturation (Ω) of 4.5 in the absence and presence of fulvic acids isolated from Big Soda Lake, Nevada (BSLFA), and a fulvic acid from the Suwannee River, Georgia (SRFA). Rates are also measured in the presence and absence of low-molar mass, aliphatic-alicyclic polycarboxylic acids (PCA). BSLFA inhibits calcite crystal-growth rates with increasing BSLFA concentration, suggesting that BSLFA adsorbs at growth sites on the calcite crystal surface. Calcite growth morphology in the presence of BSLFA differed from growth in its absence, supporting an adsorption mechanism of calcite-growth inhibition by BSLFA. Calcite growth-rate inhibition by BSLFA is consistent with a model indicating that polycarboxylic acid molecules present in BSLFA adsorb at growth sites on the calcite crystal surface. In contrast to published results for an unfractionated SRFA, there is dramatic calcite growth inhibition (at a concentration of 1 mg/L) by a SRFA fraction eluted by pH 5 solution from XAD-8 resin, indicating that calcite growth-rate inhibition is related to specific SRFA component fractions. A cyclic PCA, 1, 2, 3, 4, 5, 6-cyclohexane hexacarboxylic acid (CHXHCA) is a strong calcite growth-rate inhibitor at concentrations less than 0.1 mg/L. Two other cyclic PCAs, 1, 1 cyclopentanedicarboxylic acid (CPDCA) and 1, 1 cyclobutanedicarboxylic acid (CBDCA) with the carboxylic acid groups attached to the same ring carbon atom, have no effect on calcite growth rates up to concentrations of 10 mg/L. Organic matter ad-sorbed from the air onto the seed crystals has no effect on the measured calcite crystal-growth rates.

Nevada, Georgia↗
USGS1986

Demographic patterns of the shrub Ceanothus megacarpus in an old stand of chaparral in the Santa Monica Mountains

Wildfires have had a major influence on the structural and functional adaptations that have evolved in Mediterranean-type ecosystems. Some chaparral shrubs sprout after fires while others produce serotinous cones or seeds refractory to germination until they are cued by a fire. Ceanothus megacarpus is a sclerophylous shrub commonly found in California in either pure of mixed stands which does not survive fires but whose seeds germinate following a fire. Because in recent decades man-made fires have become frequent, few older stands remain, and they have been described as "decadent" or "senescent." Since data on older chaparral stands are scarce, a stand of chaparral in the Santa Monica Mountains of southern California, which last burned in 1929 was studied in an effort to elucidate the survivorship patterns and community structure of Ceanothus megacarpus as it ages. Ceanothus is responsible for 68 percent of the basal coverage at this mixed stand, and one-eighth of the Ceanothus were found to be dead. Over 130 such dead individuals were cut at ground level and aged by ring counts to establish the survivorship curve for this species in this chaparral community in the absence of fires.

California↗
USGS1984

Characterization and geochemistry of Devonian oil shale North Alabama - South Central Tennessee

Based on the physical and chemical data obtained to date, the Devonian oil shale rock of north Alabama and south-central Tennessee appears to offer an attractive potential for future resource development. The shale rock appears to have formed in a restrictive marine environment which provided opportunity for the accumulation of marine organic matter to form sufficient kerogen. The shale contains approximately 18% to 22% organic matter which is primarily kerogen. The kerogen has a relatively high H:C ratio indicative of an alginite and/or exinite source (Type 1 and Type II kerogen) and a high proportion of alkane and saturated ring hydrocarbons. However, a few samples have low H:C ratio values and are interpreted to have been formed in a shallow water oxidizing environment. Also, there is a possibility that these low H:C values may represent mixtures of terrestrial and marine organic material suggesting lateral facies changes of the rock from marine to near shore depositional environments. Trace metal values for both the whole rock and the shale oil fraction indicate a generally high V:Ni ratio, also indicative of a marine environment. Other trace metal values are in good agreement with data from other Devonian shales. Throughout the north Alabama and south-central Tennessee study area, the average oil yield from the shale is 13.9 gallon per ton. The highest oil yield values were obtained from the middle and upper parts of the shale sequence. Based on the crude oil composition diagram (11), the Alabama-Tennessee shale oil is classified as a aromatic-intermediate oil Estimated reserves of inplace shale oil resources in the principal study area, under less than 200 feet of overburden, exceeds 12.5 billion barrels.

Conference Paper↗
USGS1988

Decline in long-term growth trends of white oak

Quercus alba tree-ring collections from 89 locations throughout much of its range, from Connecticut to North Carolina to Iowa, were examined for evidence of growth decline initiated in the 1950s. The expected trend of annual basal area increments, based on pre-1950 growth, appears to be linear, with the slope varying among collections relative to site quality. Growth decline, defined as departure of actual growth below that expected, was identified in 40 to 60 collections judged to have not been affected by local site histories. The percentage of collections showing decline was essentially the same in the Northeast, the Midwest and the Southeast. Onset of decline began during a relatively narrow time window from the mid-1950's to the early 1960's. Since then the growth trend has been linear and appears unrelated to changes in regional sulfur and nitrogen oxide emissions. Events or conditions, unique to the 1950's, initiated a growth rate change in c 2/3 of the stands examined. Initiation of the decline appears to be unrelated to tree age, geographic location, site quality, climatic trends, or regional emissions of sulfur and nitrogen oxides. -from Authors

Canadian Journal of Forest Research↗
USGS1992

Types of phreatomagmatic volcanoes in the western Snake River Plain, Idaho, USA

The western Snake River Plain graben in southwestern Idaho includes a large hydrovolcanic field which was produced in late Miocene to Pleistocene time by the interaction of rising basaltic magmas with the waters and water-saturated deposits of an enormous freshwater lake, Lake Idaho. The phreatomagmatic volcanoes in this field may be grouped into three types: emergent, subaqueous and subaerial. Emergent volcanoes, which began erupting under water and built up above the lake level, are relatively large and symmetrical, are dominated by bedded tuffs and late magmatic deposits, and are excellent indicators of water depth at the time of the eruption. Subaqueous volcanoes, which never built up above the lake level, are relatively small and asymmetrical, are dominated by basal massive deposits, and are potentially useful in discriminating between deep- and very-deep-water settings. Subaerial volcanoes, which were formed when magmas intercepted buried aquifers and interacted explosively with water, are small tuff rings and maars with variable shapes, are composed of subequal (although variable) proportions of basal massive deposits, bedded tuffs and late magmatic deposits, and are useful in determining the stratigraphic successions underlying them. ?? 1992.

Journal of Volcanology and Geothermal Research↗
USGS1997

A note on the trilobite genus Dixiphopyge

Recovery of the first nearly complete thoracopygon of the trilobite genus Dixiphopyge Brezinski from the Chouteau Formation of central Missouri aids in evaluating the paleoecology and taxonomic affinities of this genus. Dixiphopyge is an isopygous trilobite, suboval in outline, and possessing nine thoracic segments. At the apex of each axial ring is a hollow tubercle that may represent the base of a short spine. Dixiphopyge inhabited muddy biostrome environments. In an enrolled position Dixiphopyge is interpreted to have looked somewhat like a porcupine with its spines radiating outward, presumably to inhibit its consumption by predators. Previous subfamily assignment of Dixiphopyge in the Otarioninae with Cyphaspis and Namuropyge may have been incorrect, because the latter two genera possess broad preglabellar fields and are micropygous.

Annals of Carnegie Museum↗
USGS1998

North-South precipitation patterns in western North America on interannual-to-decadal timescales

The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25??to 55??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both timescales, two leading EOFs describe 1) a north-south seesaw of precipitation pivoting near 40??N and 2) variations in precipitation near 40??N, respectively. The amount of overall precipitation variability is only about 10% of the mean and is largely determined by precipitation variations around 40??-45??N and most consistently influenced by nearby circulation patterns; in this sense, domain-average precipitation is closely related to the second EOF. The central latitude and latitudinal spread of precipitation distributions are strongly influenced by precipitation variations in the southern parts of western North America and are closely related to the first EOF. Central latitude of precipitation moves south (north) with tropical warming (cooling) in association with midlatitude western Pacific SLP variations, on both interannual and decadal timescales. Regional patterns and zonal averages of precipitation-sensitive tree-ring series are used to corroborate these patterns and to extend them into the past and appear to share much long- and short-term information with the instrumentally based zonal precipitation EOFs and moments.The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25?? to 55 ??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both tim

Journal of Climate↗
USGS2002

Temperature history of Coregonus artedi in the St. Marys River, Laurentian Great Lakes, inferred from oxygen isotopes in otoliths

The population of Coregonus artedi in the St. Marys River, between lakes Superior and Huron, was sampled and otoliths were analyzed for oxygen isotopic composition to determine whether the fish are residents in the St. Marys River and its warm bays or migrants to and from cold Lake Huron. Otoliths were extracted, sectioned, and growth ring-specific samples of calcium carbonate were milled to obtain samples for determination of oxygen isotope ratios (18O values). The 18O values of calcium carbonate (CaCO3) in accretionary structures such as otoliths allow calculation of growth temperatures of the fish, because of differential fractionation of oxygen isotopes at different temperatures. Growth temperatures of 10 St. Marys River lake herring were compared with lake and catch data as well as growth temperatures of lake herring collected from Lake Huron and other ciscoes from the Great Lakes. Results of this analysis indicate that these fish remained in the bays of the St. Marys River for their entire life history. After their second year they grew at average temperatures between 11 C and 13 C, consistent with temperature in the warmer bays of the St. Marys River and 6 C higher than expected for growth of this species in Lake Huron.

St. Marys River↗
USGS2007

Laysan Teal Anas laysanensis nesting phenology and site characteristics on Laysan Island

Factors influencing breeding initiation of the endangered Laysan Teal Anas laysanensis were studied on Laysan Island in the Hawaiian Islands National Wildlife Refuge between 1998 and 2006. Sixty-two radio-tagged adult females were tracked for 30-180 days to locate and describe their nest sites. In addition, the Laysan Teal were surveyed daily during the breeding season, and 331 individually colour-ringed females were marked to identify new broods and timing of incubation initiation. Temperature, rainfall, and abundance of Brine Flies (Scatella sexnotata, an important prey) were measured in all years. Females nested on average 213 m (s.e. ?? 37 m) from the lake basin primarily in Eragrostis variablis, a native bunch grass with > 75% cover. The first observation of nesting in marine debris by Laysan Teal was reported. The initiation of incubation, at the start of the breeding season each year, varied from December to July, and differed significantly between years. Brine Fly abundance, temperature, and rainfall also varied significantly between years. The earlier the Brine Fly abundance peaked, the longer the duration of the breeding season. The length of the breeding season, measured as the number of days between the first and last clutches, varied from 83-192 days (mean 116 ?? 14 days). Annual brood production was positively correlated with spring peak abundance of Brine Flies. There was some evidence that it was negatively correlated with the number of adult females in the population. Rainfall, temperature, prey abundance, and the density of other birds on Laysan Island are likely to interact in influencing Laysan Teal's variable nesting phenology and productivity. ?? Wildfowl & Wetlands Trust.

Wildfowl↗
USGS2009

Cahokia's boom and bust in the context of climate change

During the early Mississippian Lohmann phase (A.D. 1050-1100), the American Bottom experienced a political and economic transformation. This transformation included the abrupt planned construction of central Cahokia, a large-scale influx of people to "downtown Cahokia," the abandonment of pre-Mississippian village settlements, the reorganization of farming in the Mississippi River floodplain, and the founding of the Richland farming complex in the Illinois uplands. New tree-ring-based records of climate change indicate that this rapid development occurred during one of the wettest 50-year periods during the last millennium. During the next 150 years, a series of persistent droughts occurred in the Cahokian area which may be related to the eventual abandonment of the American Bottom. By A.D. 1150, in the latter part of a severe 15-year drought, the Richland farming complex was mostly abandoned, eliminating an integral part of Cahokia's agricultural base. At about the same time, a 20,000-log palisade was erected around Monks Mound and the Grand Plaza, indicating increased social unrest. During this time, people began exiting Cahokia and, by the end of the Stirling phase (A.D. 1200), Cahokia's population had decreased by about 50 percent and by A.D. 1350, Cahokia and much of the central Mississippi valley had been abandoned. ??2009 by the Society for American Archaeology.

American Antiquity↗
USGS2004

The Colorado Plateau: cultural, biological, and physical research

Stretching from the four corners of Arizona, New Mexico, Colorado, and Utah, the Colorado Plateau is a natural laboratory for a wide range of studies. This volume presents 23 original articles drawn from more than 100 research projects presented at the Sixth Biennial Conference of Research on the Colorado Plateau. This scientific gathering revolved around research, inventory, and monitoring of lands in the region. The book's contents cover management techniques for cultural, biological, and physical resources, representing collaborative efforts among federal, university, and private sector scientists and land managers. Chapters on cultural concerns cover benchmarks of modern southwestern anthropological knowledge, models of past human activity and impact of modern visitation at newly established national monuments, challenges in implementing the 1964 Wilderness Act, and opportunities for increased federal research on Native American lands. The section on biological resources comprises sixteen chapters, with coverage that ranges from mammalian biogeography to responses of elk at the urban-wildland interface. Additional biological studies include the effects of fire and grazing on vegetation; research on bald eagles at Grand Canyon and tracking wild turkeys using radio collars; and management of palentological resources. Two final chapters on physical resources consider a proposed rerouting of the Rio de Flag River in urban Flagstaff, Arizona, and an examination of past climate patterns over the Plateau, using stream flow records and tree ring data. In light of similarities in habitat and climate across the Colorado Plateau, techniques useful to particular management units have been found to be applicable in many locations. This volume highlights an abundance of research that will prove useful for all of those working in the region, as well as for others seeking comparative studies that integrate research into land management actions.

Utah;Colorado;Arizona;New Mexico↗
USGS1973

Preliminary geologic investigation of the Apollo 17 landing site

The Apollo 17 lunar module (LM) landed on the flat floor of a deep valley that embays the mountainous highlands at the eastern rim of the Serenitatis basin. Serenitatis, the site of a pronounced mascon, is one of the major multi-ringed basins on the near side of the Moon. The Taurus-Littrow valley, which is radial to the Serenitatis basis, is interpreted as a deep graben formed by structural adjustment of lunar crustal material to the Serenitatis impact.

Book chapter↗
USGS1973

Remote sensing and photogrammetric studies: Part A: remote sensing of Mare Serenitatis

Mare Serenitatis is a circular mare approximately 600 km in diameter in the northeast quadrant of the lunar near side. It occupies an old multi-ringed basin (refs. 33-1 and 33-2) and is the site of a prominent mascon (ref. 33-3). A conspicuous dark annulus in this mare prompted subdivision of the mare materials into different stratigraphic units (refs. 33-2 and 33-4). A revised stratigraphic sequence for the southern part of Mare Serenitatis, based on photogeologic interpretation of Apollo 15 and 17 photographs, is summarized as follows after Howard et al.

Book chapter↗
USGS1972

Photogeology: Part B: Cayley Formation interpreted as basin ejecta

The discovery that samples returned from the Cayley Formation at the Apollo 16 landing site consist mainly of nonvolcanic breccias (secs. 6 and 7 of this report) suggests that the hypothesis in which light plains-forming materials may be ejecta from multi-ring basins should be reevaluated (refs 29-15 to 29-17). Improved information on the morphology and distribution of the Cayley Formation, provided by Apollo 16 orbital photography, leads to a concept in which the Cayley Formation was deposited as fluidized debris that traveled beyond the presently recognizable extent of the Imbrium Basin ejecta. An elaboration of this genetic model is in preparation; the description, a summary of the model, and its implications are presented in this subsection.

Book chapter↗
USGS1979

Relation of mercury, uranium, and lithium deposits to the McDermitt caldera complex, Nevada-Oregon

The McDermitt caldera complex, located along the Nevada-Oregon border, is a Miocene collapse structure 45 km in diameter. Large-volume rhyolitic and peralkaline ash-flow tufts were erupted from 17.9-15.8 m.y. ago, leading to the formation of overlapping and nested calderas. Emplacement of rhyolitic ring domes, located primarily along the western margin of the calderas, represents the last phase of volcanic activity.

Nevada;Oregon↗
USGS2000

Volumetric evolution of Surtsey, Iceland, from topographic maps and scanning airborne laser altimetry

The volumetric evolution of Surtsey has been estimated on the basis of digital elevation models derived from NASA scanning airborne laser altimeter surveys (20 July 1998), as well as digitized 1:5,000-scale topographic maps produced by the National Land Survey of Iceland and by Norrman. Subaerial volumes have been computed from co-registered digital elevation models (DEM's) from 6 July 1968, 11 July 1975, 16 July 1993, and 20 July 1998 (scanning airborne laser altimetry), as well as true surface area (above mean sea level). Our analysis suggests that the subaerial volume of Surtsey has been reduced from nearly 0.100 km 3 on 6 July 1968 to 0.075 km 3 on 20 July 1998. Linear regression analysis of the temporal evolution of Surtsey's subaerial volume indicates that most of its subaerial surface will be at or below mean sea-level by approximately 2100. This assumes a conservative estimate of continuation of the current pace of marine erosion and mass-wasting on the island, including the indurated core of the conduits of the Surtur I and Surtur II eruptive vents. If the conduits are relatively resistant to marine erosion they will become sea stacks after the rest of the island has become a submarine shoal, and some portions of the island could survive for centuries. The 20 July 1998 scanning laser altimeter surveys further indicate rapid enlargement of erosional canyons in the northeastern portion of the partial tephra ring associated with Surtur I. Continued airborne and eventually spaceborne topographic surveys of Surtsey are planned to refine the inter-annual change of its subaerial volume.

Surtsey↗
USGS2014

Delineation of Tundra Swan Cygnus c. columbianus populations in North America: geographic boundaries and interchange

North American Tundra Swans Cygnus c. columbianus are composed of two wellrecognised populations: an Eastern Population (EP) that breeds across northern Canada and north of the Brooks Range in Alaska, which migrates to the eastern seaboard of the United States, and a Western Population (WP) that breeds in coastal regions of Alaska south of the Brooks Range and migrates to western North America. We present results of a recent major ringing effort from across the breeding range in Alaska to provide a better definition of the geographic extent of the migratory divide in Alaska. We also reassess the staging and winter distributions of these populations based on locations of birds tracked using satellite transmitters, and recent recoveries and sightings of neck-collared birds. Summer sympatry of EP and WP Tundra Swans is very limited, and largely confined to a small area in northwest Alaska. Autumn migration pathways of EP and WP Tundra swans abut in southwest Saskatchewan, a region where migrating WP birds turn west, and EP birds deviate abruptly eastward. Overall, from 1989 to 2013 inclusive, 2.6% of recoveries or resightings reported to the USGS Bird Banding Laboratory were of birds that moved from the domain of the population in which they were initially captured to within the range of the other population; a proportion roughly comparable to the results of Limpert et al . (1991) for years before 1990. Of the 70 cross-boundary movements reported since 1989, 39% were of birds marked on breeding areas and 61% were of birds marked on wintering areas. Dispersing swans (i.e. those that made crossboundary movements) did not differ with respect to age or sex from those that did not move between populations. The Brooks Range in northern Alaska effectively separates the two populations within Alaska, but climate-induced changes in tundra breeding habitats and losses of wetlands on staging areas may alter the distribution for both of these populations.

Wildfowl↗