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At least 19 recordsLinked to original sources
USGS2015

NACSN, note 67--Application for revision of Articles 36 and 37, Lithodemic units of the North American stratigraphic code

Currently the North American Stratigraphic Code, (NACSN 2005, Article 37) sets restrictions on the use of the term “complex” for lithodemic units. With exceptions for “volcanic complex” and “structural complex,” a complex must consist of more than one genetic class of rock (i.e., sedimentary, igneous or metamorphic). Thus, the use of the term “complex” to describe masses of intrusive rocks is not allowed. Asimilar restriction is also included in a recent British Geological Survey proposal for using lithodemic units to classify igneous rocks (Gillespie et al. 2008).Currently the North American Stratigraphic Code, (NACSN 2005, Article 37) sets restrictions on the use of the term “complex” for lithodemic units. With exceptions for “volcanic complex” and “structural complex,” a complex must consist of more than one genetic class of rock (i.e., sedimentary, igneous or metamorphic). Thus, the use of the term “complex” to describe masses of intrusive rocks is not allowed. Asimilar restriction is also included in a recent British Geological Survey proposal for using lithodemic units to classify igneous rocks (Gillespie et al. 2008).

Stratigraphy↗
USGS1983

A description of the external and internal quiet daily variation currents at North American locations for a quiet-Sun year.

An order 4, degree 12 spherical harmonic analysis of the smoothed quiet geomagnetic daily variations was used to separate the external and internal geomagnetic Sq field at North American locations for the quiet-Sun year, 1965. These fields were represented by a month-by-month display of equivalent current vortex systems with dominant, pre-noon foci. The focus reached 40o latitude near the June solstice and about 30o latitude near the December solstice. The daily range of Sq current amplitudes was largest in late July to early August and smallest in mid-December. Semi-annual variations of Sq currents dominated only the equatorial region. Daily maxima in mid-latitudes, occurred mostly near local noon in December to February and about 1 hr before noon in June to mid-October. -Author

Geophysical Journal of the Royal Astronomical Soci↗
USGS2016

Mechanistic variables can enhance predictive models of endotherm distributions: The American pika under current, past, and future climates

How climate constrains species’ distributions through time and space is an important question in the context of conservation planning for climate change. Despite increasing awareness of the need to incorporate mechanism into species distribution models (SDMs), mechanistic modeling of endotherm distributions remains limited in this literature. Using the American pika ( Ochotona princeps ) as an example, we present a framework whereby mechanism can be incorporated into endotherm SDMs. Pika distribution has repeatedly been found to be constrained by warm temperatures, so we used Niche Mapper, a mechanistic heat-balance model, to convert macroclimate data to pika-specific surface activity time in summer across the western United States. We then explored the difference between using a macroclimate predictor (summer temperature) and using a mechanistic predictor (predicted surface activity time) in SDMs. Both approaches accurately predicted pika presences in current and past climate regimes. However, the activity models predicted 8–19% less habitat loss in response to annual temperature increases of ~3–5 °C predicted in the region by 2070, suggesting that pikas may be able to buffer some climate change effects through behavioral thermoregulation that can be captured by mechanistic modeling. Incorporating mechanism added value to the modeling by providing increased confidence in areas where different modeling approaches agreed and providing a range of outcomes in areas of disagreement. It also provided a more proximate variable relating animal distribution to climate, allowing investigations into how unique habitat characteristics and intraspecific phenotypic variation may allow pikas to exist in areas outside those predicted by generic SDMs. Only a small number of easily obtainable data are required to parameterize this mechanistic model for any endotherm, and its use can improve SDM predictions by explicitly modeling a widely applicable direct physiological effect: climate-imposed restrictions on activity. This more complete understanding is necessary to inform climate adaptation actions, management strategies, and conservation plans.

Global Change Biology↗
USGS2011

North American Jurassic APW: The current dilemma

Geologists are in a quandary over the correct interpretation of paleomagnetic data for Jurassic rocks of the North American plate. Conflicting reference paleopoles and alternate methods of constructing apparent polar wander (APW) paths have led to a controversy regarding the configuration of Jurassic APW for cratonic North America. These differences have been recently disputed at meetings (see Eos , Spring Meeting Supplement, April 7, 1992, p. 94) and in an exchange of letters in the Journal of Geophysical Research-Solid Earth [ Butler et al ., 1992; Van Fossen and Kent , 1992a]. At stake is important information concerning the Jurassic paleogeography of North America and the whole of Pangea, as well as the nature and driving mechanism of plate movements. In addition, cratonic paleopoles provide a reference frame for measuring relative displacements of tectonostratigraphic terranes.

Eos Science News↗
USGS2010

Current distribution of North American river otters in central and eastern Oklahoma, with seven new county records

In 1984 and 1985, the Oklahoma Department of Wildlife Conservation reintroduced North American river otters (Lontra canadensis) from coastal Louisiana into eastern Oklahoma. Those reintroductions and immigration from Arkansas and possibly northeastern Texas allowed river otters to become reestablished in eastern Oklahoma. Our goals were to determine the contemporary distribution of river otters in central and eastern Oklahoma with voucher specimens, sign surveys, and mail surveys and to compare proportion of positive detections among watersheds. We report new distributional records with voucher specimens from seven counties (Adair, Bryan, Coal, Johnston, McIntosh, Okfuskee, Tulsa) in Oklahoma. We also provide locality information for specimens collected from four counties (Haskell, McCurtain, Muskogee, Wagoner) where river otters were described in published literature but no voucher specimens existed. During winter and spring 2006 and 2007, we visited 340 bridge sites in 28 watersheds in eastern and central Oklahoma and identified river otter signs in 16 counties where river otters were not previously documented in published literature or by voucher specimens. Proportion of positive sites within each watershed ranged 0–100%. Mail surveys suggested that river otters occurred in eight additional counties where they were not previously documented by published literature, voucher specimens, or sign-survey efforts.

Oklahoma↗
USGS2014

Sex in the Suwannee, the secretive love life of Gulf Sturgeons

Mid-February in the Gulf of Mexico and a timeless ritual is about to repeat itself for perhaps the millionth time. Some mysterious signal, possibly increasing day length, flips an internal switch, feeding stops, and the homeward migration begins for the Gulf Sturgeon ( Acipenser oxyrinchus desotoi ). From far flung places along the Gulf Coast, Gulf Sturgeons start heading back to their natal rivers – they know the way instinctively. Maybe they seek out the special chemical taste of their home river, imprinted at hatching. Or perhaps the ultrasensitive electric organs decorating the underside of the snout can follow the map of the earth’s magnetic field. Either way, time to make a beeline for the welcoming waters of the Suwannee River, or maybe the Apalachicola, Choctawhatchee, or one of four other spawning rivers. Some of the adults are on a special mission – time to spawn, time to perpetuate the species. Mature males form the first wave in this homebound marathon, eager to get to the spawning grounds, eager to be the first to greet ready females with a series of sharp clicking sounds. Only spawning once each three years, females laden with large black eggs demure, taking their time, arriving in mid to late March, a month behind the early males. But most sturgeons, juveniles and immature adults not ready to spawn, are simply heading home. Not prompted by the spawning urge, they are just following the ancient annual cycle of intense winter feeding in the Gulf, followed by several months of fasting and R&R in the river.

Alabama, Florida, Georgia, Louisiana, Mississippi↗
USGS2006

The role of reproductive behavior in the conservation of fishes: examples from the Great Plains riverine fishes

Recovery efforts for threatened and endangered fish species are hampered by lack of knowledge of their reproductive ecology. Habitat requirements and environmental stimuli necessary for reproduction are often unknown and vary widely among species. For Great Plains riverine fishes, this is often complicated by the high turbidity of the system in which the species occur, which precludes direct visual observation of behavior. Innovative methods for collectng behavioral data are required to better understand the conditions necessary for successful reproduction.

American Currents↗
USGS2018

Terrestrial wetlands

1. The assessment of terrestrial wetland carbon stocks has improved greatly since the First State of the Carbon Cycle Report (CCSP 2007) because of recent national inventories and the development of a U.S. soils database. Terrestrial wetlands in North America encompass an estimated 2.2 million km 2 , which constitutes about 37% of the global wetland area, with a soil and vegetation carbon pool of about 161 petagrams of carbon that represents approximately 36% of global wetland carbon stock. Forested wetlands compose 55% of the total terrestrial wetland area, with the vast majority occurring in Canada. Organic soil wetlands or peatlands contain 58% of the total terrestrial wetland area and 80% of the carbon ( high confidence, likely ). 2. North American terrestrial wetlands currently are a carbon dioxide sink of about 123 teragrams of carbon (Tg C) per year, with approximately 53% occurring in forested systems. However, North American terrestrial wetlands are a natural source of methane (CH 4 ), with mineral soil wetlands emitting 56% of the estimated total of 45 Tg C as CH 4 (CH 4 –C) per year ( medium confidence, likely ). 3. The current rate of terrestrial wetland loss is much less than historical rates (about 0.06% of the wetland area from 2004 to 2009), with restoration and creation nearly offsetting losses of natural wetlands. Although area losses are nearly offset, there is considerable uncertainty about the functional equivalence of disturbed, created, and restored wetlands when comparing them to undisturbed natural wetlands. Correspondingly, there remains considerable uncertainty about the effects of disturbance regimes on carbon stocks and greenhouse gas (GHG) fluxes. For this reason, studies and monitoring systems are needed that compare carbon pools, rates of carbon accumulation, and GHG fluxes across disturbance gradients, including restored and created wetlands. Those studies will produce data that are needed for model applications ( high confidence, likely ).

Report↗
USGS1996

First-time observer effects in the North American Breeding Bird Survey

Currently the operational analysis of Breeding Bird Survey (BBS) data by the National Biological Service accounts for observer differences in estimating the trend for each route, but within-observer differences are not modeled. We tested for the existence of a form of within-observer differences in skill level, namely a change in ability to count birds of a given species after an observer's first year on a given route. An increase in ability could positively bias the trend estimate. Removal of an observer's first year of observation on each route for the period 1966 to 1991 resulted in lower average unweighted trend estimates for 415 of 459 species (90%). These reductions were statistically significant for 213 species (46%). The average reduction in trend was 1.8% change per year (SD = 5.4%). In route-regression analysis, route data are weighted by a measure of precision. Removing first-year observer counts reduced the weighted trend estimate for 275 of 416 species (66%), but differences generally were small.

The Auk↗
USGS1993

Critical review of the current knowledge of the biology of the American woodcock and its management on the breeding grounds

We critiqued previous work on the biology and management of the American woodcock (Scolopax minor) on the breeding grounds. We determined that little is known about habitat variables and weather extremes that may limit the population. Most investigators who attempted to define habitat requirements of the woodcock used inadequate sample sizes, limited the duration of their studies, did not account for effects of weather, or failed to adequately measure habitat variables. Furthermore, the effects of hunting on local or regional populations has never been adequately studied. We concluded that obtaining data to understand the biology of the woodcock and the effects of hunting is essential before managers can reverse the long-term decline of woodcock numbers.

Biological Report↗
USGS1993

A speculative history of the San Andreas fault in the central Transverse Ranges, California

It is generally accepted that the San Andreas fault formed between 4 and 5 Ma and that rocks west of it are now part of the Pacific plate, moving northwest relative to North America at 5 to 6 cm/yr. This model is inconsistent with the geologic record in the central Transverse Ranges. Right-lateral shear began in the vicinity of the San Andreas fault system in early Miocene time. The San Andreas fault system in the central Transverse Ranges has since evolved through three major phases; this development has led to a generally simpler, more throughgoing main trace. Slip rates on the San Andreas system were about 1 cm/yr in the Miocene, increasing to their current level of 3.5 cm/yr between 4 and 5 Ma. The modern San Andreas fault still only accounts for just over half the current relative plate rate and retains kinematic complexities inherited from its earliest geometry. The Early San Andreas transform system originated during early Miocene time in one of three transtensive zones that lay interior to the continent and east of the locus of transform motion between the Pacific and North American plates. The current three-fold division of motion in the plate boundary between the San Andreas fault, a coastal system, and an eastern California system dates to this time, as does the “anomalous” trend of the San Andreas fault through the Transverse Ranges. Basins and volcanic centers associated with this transtensive zone became dismembered as faults became integrated into a throughgoing system. Early motion led to juxtaposition of different rocks across faults now recognized as part of the Early San Andreas transform system, and to the development of sedimentary provincialism associated with uplift along the fault zone. Middle Miocene basins, including the Caliente, Cajon, Crowder, and Santa Ana basins that had previously received most of their sediments from sources far to the east, began to reflect local Transverse Ranges provenance. At least 100 km of slip is associated with the Early San Andreas transform system during early and middle Miocene time. Slip across the geometrically complex late Miocene San Gabriel transform system—which includes the San Gabriel, Cajon Valley, and early Punchbowl faults—produced uplift in the proto-Transverse Ranges at a postulated restraining bend in the fault system. Compressional structures associated with this restraining bend include the Squaw Peak and Liebre Mountain thrusts, related east-striking late Miocene reverse faults and folds, and, perhaps, northeast-striking left-lateral faults in the San Gabriel Mountains. Narrow fault-controlled basins formed during this period, including the Ridge basin, Devil’s Punchbowl basin, Mill Creek basin, and part of the Santa Ana Sandstone basin. Offset of structures and relief associated with the proto-Transverse Ranges provides the best evidence for late Miocene restorations of the modern San Andreas fault. As much as 60 km of offset is associated with the late Miocene San Gabriel transform system. Between 4 and 5 Ma, the modern San Andreas fault became the dominant member of the plate boundary system, cutting through the proto-Transverse Ranges and connecting more northerly striking traces to the north and south. The slip rate across the San Andreas fault system accelerated from 1 cm/yr to its current slip rate of 3.5 cm/yr prior to 4 Ma. The Pliocene rocks in the central Transverse Ranges do not contain evidence for relief as great as that of late Miocene or Quaternary time. The Pliocene trace of the modern San Andreas fault may have temporarily “solved” the geometric problem that led to late Miocene uplift. About 90 km of right-lateral displacement occurred on the modern San Andreas fault during Pliocene time. During Quaternary time new regions of localized vertical deformation developed in the Transverse Ranges, apparently as the result of new geometric problems within the Pliocene solution to the restraining geometry of the fault system. Left-lateral motion on east-striking faults, probably due to a northward increase in Basin and Range extension, kinked the San Andreas fault at both ends of the Transverse Ranges, producing regions of extreme shortening and uplift. The development of young right-lateral faults through the Peninsular Ranges, including the San Jacinto and Elsinore faults, also contributed to renewed uplift in the Transverse Ranges. Sixty kilometers of right-lateral slip occurred across the San Andreas fault zone during Quaternary time.

California↗
USGS1998

Paleomagnetic evidence that the central block of Salinia (California) is not a far-traveled terrane

New paleomagnetic results from Late Cretaceous (75–85 m.y.) red beds on the central block of Salinia indicate that Salinia was located within 6° (in latitude) of its current cratonal North American position during the Late Cretaceous (after correction for Neogene San Andreas Fault transport). The red beds formed as alluvial-fan overbank deposits with hematite cement deposited directly on Salinian granites in the La Panza Range. Paleomagnetic analysis shows two components of magnetization in the red beds, a low-blocking-temperature present-day overprint residing in goethite and a high-blocking-temperature (>600°) component residing in hematite. The hematite magnetization is a chemical remanent magnetization which formed soon after deposition during pedogenesis. The bedding-corrected hematite remanence contains a magnetic polarity stratigraphy with antipodal normal and reversed directions. Twenty-three Class I sites (α 95 < 20°) have an average hematite direction with inclination =54.4° and declination = 18.2° (α 95 = 6.1°) after structural correction. These paleomagnetic data suggest that Salinia resided at about 35°N latitude during the Late Cretaceous, within 6° of its current location adjacent to cratonal North America. By contrast, a summary of paleomagnetic data from the Peninsular Ranges terrane and the Sur-Obispo terrane, which are currently outboard of Salinia, shows northward transport of these terranes of 12° to 22° relative to their current locations in North America since the Cretaceous. The offsets increase systematically away from the craton with the most outboard Sur-Obispo terrane (which is composed of accretionary prism and distal forearc material) showing the largest degree of northward translation.

California↗
USGS2019

Virally-vectored vaccine candidates against white-nose syndrome induce anti-fungal immune response in little brown bats (Myotis lucifugus)

White-nose syndrome (WNS) caused by the fungus, Pseudogymnoascus destructans ( Pd ) has killed millions of North American hibernating bats. Currently, methods to prevent the disease are limited. We conducted two trials to assess potential WNS vaccine candidates in wild-caught Myotis lucifugus . In a pilot study, we immunized bats with one of four vaccine treatments or phosphate-buffered saline (PBS) as a control and challenged them with Pd upon transfer into hibernation chambers. Bats in one vaccine-treated group, that received raccoon poxviruses (RCN) expressing Pd calnexin (CAL) and serine protease (SP), developed WNS at a lower rate (1/10) than other treatments combined (14/23), although samples sizes were small. The results of a second similar trial provided additional support for this observation. Bats vaccinated orally or by injection with RCN-CAL and RCN-SP survived Pd challenge at a significantly higher rate (P = 0.01) than controls. Using RT-PCR and flow cytometry, combined with fluorescent in situ hybridization, we determined that expression of IFN-γ transcripts and the number of CD4 + T-helper cells transcribing this gene were elevated (P < 0.10) in stimulated lymphocytes from surviving vaccinees (n = 15) compared to controls (n = 3). We conclude that vaccination with virally-vectored Pd antigens induced antifungal immunity that could potentially protect bats against WNS.

Scientific Reports↗
USGS2006

The quest for the perfect gravity anomaly: Part 2 - Mass effects and anomaly inversion

Gravity anomalies have become an important tool for geologic studies since the widespread use of high-precision gravimeters after the Second World War. More recently the development of instrumentation for airborne gravity observations, procedures for acquiring data from satellite platforms, the readily available Global Positioning System for precise vertical and horizontal control, improved global data bases, and enhancement of computational hardware and software have accelerated the use of the gravity method. As a result, efforts are being made to improve the gravity databases that are made available to the geoscience community by broadening their observational holdings and increasing the accuracy and precision of the included data. Currently the North American Gravity Database as well as the individual databases of Canada, Mexico, and the United States of America are being revised using new formats and standards. The objective of this paper is to describe the use of the revised standards for gravity data processing and modeling and there impact on geological interpretations. ?? 2005 Society of Exploration Geophysicists.

SEG Technical Program Expanded Abstracts↗