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At least 145 records · Page 8Linked to original sources

USGS2000

Parent brine of the castile evaporites (Upper Permian), Texas and New Mexico

The Upper Permian (lower Ochoan) Castile Formation is a major evaporite sequence (∼10,000 km 3 ) of calcite, anhydrite, and halite in west Texas and southeastern New Mexico. Traditionally the Castile brine has been considered to have been derived from seawater. This tradition has recently been challenged by two versions of the closed-basin drawdown model. They call for deposition from a mixed brine, in part marine and in large part nonmarine. They propose drawdown of as much as 500 m to form a major sink for ground water issuing from the surrounding Capitan reef complex. A large fraction of the solute in the brine body is inferred to have been recycled from older Permian evaporites on the surrounding shelf. Strontium-isotope analyses show no evidence that meteoric ground water was contributed to the Castile brine. From a stratigraphic, geographic, and lithologic array of 65 samples of anhydrite, gypsum, and calcite, 59 have an 87 Sr/ 86 Sr ratio of 0.706923 (Δsw of -225.0), a ratio that is the same as that of strontium in early Ochoan ocean water. If considerable (>15%) influx of meteoric water had occurred, enough continental strontium would have been introduced to have resulted in higher ratios. Low bromide values (20-40 ppm) in Castile halite, which have been used to argue for meteoric influx and for recycled salt, probably resulted from diagenesis. During shallow burial by halite, centimeter-size, bottom-grown crystals of gypsum were altered to nodular anhydrite. The rising water of dehydration caused the halite to recrystallize. During the recrystallization, some bromide was expelled. Despite the large volume of water that evaporated annually from its surface (∼52 km 3 /yr, assuming an evaporation rate of 2 m/yr), the Castile brine body never completely desiccated. The surrounding shelf was flat, hot, and generally dry. It probably could not have supplied a significant volume of meteoric spring water to the basin over tens of thousands of years. More likely, during the entire history of the evaporite sequence, influx was dominantly marine. Marine ground water flowed through the Capitan Formation into the evaporite basin along its southern and possibly western margin probably with a rate of flow that was usually fast enough to prevent major drawdown of the brine surface.

Journal of Sedimentary Research↗

USGS2006

Regional evaluation of the hydrogeologic framework, hydraulic properties, and chemical characteristics of the intermediate aquifer system underlying southern west-central Florida

Three major aquifer systems-the surficial aquifer system, the intermediate aquifer system, and the Floridan aquifer system-are recognized in the approximately 5,100-square-mile southern west-central Florida study area. The principal source of freshwater for all uses is ground water supplied from the three aquifer systems. Ground water from the intermediate aquifer system is considered only moderately abundant compared to the Upper Floridan aquifer, but it is an important source of water where the Upper Floridan aquifer contains water too mineralized for most uses. In the study area, the potential ground-water resources of the intermediate aquifer system were evaluated by regionally assessing the vertical and lateral distribution of hydrogeologic, hydraulic, and chemical characteristics. Although the intermediate aquifer system is considered a single entity, it is composed of multiple water-bearing zones separated by confining units. Deposition of a complex assemblage of carbonate and siliciclastic sediments during the late Oligocene to early Pliocene time resulted in discontinuities that are reflected in transitional and abrupt contacts between facies. Discontinuous facies produce water-bearing zones that may be locally well-connected or culminate abruptly. Changes in the depositional environment created the multilayered intermediate aquifer system that contains as many as three zones of enhanced water-bearing capacity. The water-bearing zones consist of indurated limestone and dolostone and in some places unindurated sand, gravel, and shell beds, and these zones are designated, in descending order, as Zone 1, Zone 2, and Zone 3. Zone 1 is thinnest (<80 feet thick) and is limited to <20 percent (southern part) of the study area. Zone 2, the only regionally extensive zone, is characterized by moderately low permeability. Zone 3 is found in about 50 percent of the study area, has the highest transmissivities, and generally is in good hydraulic connection with the underlying Upper Floridan aquifer. In parts of the study area, particularly in southwestern Hillsborough County and southeastern De Soto and Charlotte Counties, Zone 3 likely is contiguous with and part of the Upper Floridan aquifer. Transmissivity of the intermediate aquifer system ranges over five orders of magnitude from about 1 to more than 40,000 feet squared per day (ft2/d), but rarely exceeds 10,000 ft2/d. The overall transmissivity of the intermediate aquifer system is substantially lower (2 to 3 orders of magnitude) than the underlying Upper Floridan aquifer. Transmissivity varies vertically among the zones within the intermediate aquifer system; Zone 2 has the lowest median transmissivity (700 ft2/d), Zone 1 has a moderate median transmissivity (2,250 ft2/d), and Zone 3 has the highest median transmissivity (3,400 ft2/d). Additionally, the transmissivity varies geographically (from site to site) within a zone. Specifically, a region of relatively low transmissivity (<100 ft2/d) throughout the vertical extent of the intermediate aquifer system is present in the central part of the study area. This low transmissivity region is encompassed by a larger region of moderately low transmissivity (<1,000 ft2/d) that covers a large part of the study area. Clay beds and fine-grained carbonates form the confining units between the water-bearing zones and are characterized by low leakance. Leakance through the intermediate aquifer system confining units ranges over 4 orders of magnitude from 4.2x10-7 to 6.0x10-3 feet per day per foot [(ft/d)/ft]. Despite the large range, the geometric mean and median leakances of individual confining units are within the same order of magnitude, 10-5 (ft/d)/ft, which is 2 orders of magnitude less than the median leakance of the semiconfining unit within the Upper Floridan aquifer. Major ion concentrations in water from the intermediate aquifer system, and throughout the ground-water flow system, generally increase with depth. T

Scientific Investigations Report↗

USGS2005

Cubic map algebra functions for spatio-temporal analysis

We propose an extension of map algebra to three dimensions for spatio-temporal data handling. This approach yields a new class of map algebra functions that we call "cube functions." Whereas conventional map algebra functions operate on data layers representing two-dimensional space, cube functions operate on data cubes representing two-dimensional space over a third-dimensional period of time. We describe the prototype implementation of a spatio-temporal data structure and selected cube function versions of conventional local, focal, and zonal map algebra functions. The utility of cube functions is demonstrated through a case study analyzing the spatio-temporal variability of remotely sensed, southeastern U.S. vegetation character over various land covers and during different El Nin??o/Southern Oscillation (ENSO) phases. Like conventional map algebra, the application of cube functions may demand significant data preprocessing when integrating diverse data sets, and are subject to limitations related to data storage and algorithm performance. Solutions to these issues include extending data compression and computing strategies for calculations on very large data volumes to spatio-temporal data handling.

Cartography and Geographic Information Science↗

USGS2014

Decreased atmospheric sulfur deposition across the southeastern U.S.: When will watersheds release stored sulfate?

Emissions of sulfur dioxide (SO 2 ) to the atmosphere lead to atmospheric deposition of sulfate (SO 4 2- ), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States (U.S.). Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO 2 in this region has declined by over 80%, but few corresponding decreases in stream-water SO 4 2- concentrations have been observed in unglaciated watersheds. We calculated SO 4 2- mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO 4 2- , unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO 4 2- over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO 4 2- correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO 4 2- retention to release anticipates more widespread reductions in stream-water SO 4 2- concentrations in this region.

Environmental Science & Technology↗

USGS2017

Evolution, biogeography, and systematics of Puriana: evolution and speciation in Ostracoda, III.

Three types of geographic isolation—land barriers, deep water barriers, and climatic barriers—resulted in three distinct evolutionary responses in Neogene and Quaternary species of the epineritic ostracode genus Puriana . Through systematic, paleobiogeographic, and morphologic study of several hundred fossil and Recent populations from the eastern Pacific, western Atlantic, Gulf of Mexico, and the Caribbean, the phylogeny of the genus and the geography of speciation events were determined. Isolation of large populations by the Isthmus of Panama during the Pliocene did not lead to lineage splitting in species known to have existed before the Isthmus formed. Conversely, the establishment of small isolated populations on Caribbean islands by passive dispersal mechanisms frequently led to the evolution of new species or subspecies. Climatic changes along the southeastern United States during the Pliocene also catalyzed possible parapatric speciation as populations that immigrated to the northeastern periphery of the genus' range split to form new species. The results provide evidence that evolutionary models describing the influence of abiotic events on patterns of evolution and speciation can be tested using properly selected tectonic and climatic events and fossil groups amenable to species-level analysis. Two new species, P. bajaensis and P. paikensis , are described.

Journal of Paleontology↗

USGS2010

Relation of urbanization to stream habitat and geomorphic characteristics in nine metropolitan areas of the United States

The relation of urbanization to stream habitat and geomorphic characteristics was examined collectively and individually for nine metropolitan areas of the United States?Portland, Oregon; Salt Lake City, Utah; Denver, Colorado; Dallas?Forth Worth, Texas; Milwaukee?Green Bay, Wisconsin; Birmingham, Alabama; Atlanta, Georgia; Raleigh, North Carolina; and Boston, Massachusetts. The study was part of a larger study conducted by the U.S. Geological Survey from 1999 to 2004 to examine the effects of urbanization on the physical, chemical, and biological components of stream ecosystems. The objectives of the current study were to determine how stream habitat and geomorphic characteristics relate to different aspects of urbanization across a variety of diverse environmental settings and spatial scales. A space-for-time rural-to-urban land-cover gradient approach was used. Reach-scale habitat data and geomorphic characteristic data were collected once during low flow and included indicators of potential habitat degradation such as measures of channel geometry and hydraulics, streambed substrate, low-flow reach volume (an estimate of base-flow conditions), habitat complexity, and riparian/bank conditions. Hydrologic metrics included in the analyses were those expected to be altered by increases in impervious surfaces, such as high-flow frequency and duration, flashiness, and low-flow duration. Other natural and human features, such as reach-scale channel engineering, geologic setting, and slope, were quantified to identify their possible confounding influences on habitat relations with watershed-scale urbanization indicators. Habitat and geomorphic characteristics were compared to several watershed-scale indicators of urbanization, natural landscape characteristics, and hydrologic metrics by use of correlation analyses and stepwise linear regression. Habitat and geomorphic characteristics were related to percentages of impervious surfaces only in some metropolitan areas and environmental settings. The relations between watershed-scale indicators of urbanization and stream habitat depended on physiography and climate, hydrology, pre-urban channel alterations, reach-scale slope and presence of bedrock, and amount of bank stabilization and grade control. Channels increased in size with increasing percentages of impervious surfaces in southeastern and midwestern metropolitan areas regardless of whether the pre-existing land use was forest or agriculture. The amount of enlargement depended on annual precipitation and frequency of high-flow events. The lack of a relation between channel enlargement and increasing impervious surfaces in other metropolitan areas was thought to be confounded by pre-urbanization hydrologic and channel alterations. Direct relations of channel shape and streambed substrate to urbanization were variable or lacking, probably because the type, amount, and source of sediment are dependent on the phase of urbanization. Reach-scale slope also was important for determining variations in streambed substrate and habitat complexity (percentage of riffles and runs). Urbanization-associated changes in reach-scale riparian vegetation varied geographically, partially depending on pre-existing riparian vegetation characteristics. Bank erosion increased in Milwaukee?Green Bay and Boston urban streams, and bank erosion also increased with an increase in a streamflow flashiness index. However, potential relations likely were confounded by the frequent use of channel stabilization and bank protection in urban settings. Low-flow reach volume did not decrease with increasing urbanization, but instead was related to natural landscape characteristics and possibly other unmeasured factors. The presence of intermittent bedrock in some sampled reaches likely limited some geomorphic responses to urbanization, such as channel bed erosion. Results from this study emphasize the importance of including a wide range of landscape variables at m

Scientific Investigations Report↗

USGS2009

Bathymetric, Velocity, Streamflow, and Dissolved Oxygen Data on the Pee Dee River near Bostick Boat Landing, Florence County, South Carolina, May-August 2007

Santee Cooper is planning to construct an electricity generating station in southeastern Florence County near the Kingsburg community. As part of this project, a water-intake structure will be constructed on the Pee Dee River near the Bostick Boat Landing, which is located east of the intersection of State secondary roads S-21-57 and S-21-66. Velocity, bathymetric, and dissolved oxygen data are needed to help determine the location for the water-intake structure. The U.S. Geological Survey (USGS), in cooperation with Santee Cooper, collected these data at three different flow regimes during the period of May through August 2007. Data were collected along 15 transects located at 50-foot intervals starting 400 feet upstream from the boat landing and continuing to 300 feet downstream from the boat landing. All data were geographically referenced using a differentially corrected global positioning system (GPS).

South Carolina↗

USGS2015

Performance metrics and variance partitioning reveal sources of uncertainty in species distribution models

Species distribution models (SDMs) are widely used in basic and applied ecology, making it important to understand sources and magnitudes of uncertainty in SDM performance and predictions. We analyzed SDM performance and partitioned variance among prediction maps for 15 rare vertebrate species in the southeastern USA using all possible combinations of seven potential sources of uncertainty in SDMs: algorithms, climate datasets, model domain, species presences, variable collinearity, CO 2 emissions scenarios, and general circulation models. The choice of modeling algorithm was the greatest source of uncertainty in SDM performance and prediction maps, with some additional variation in performance associated with the comprehensiveness of the species presences used for modeling. Other sources of uncertainty that have received attention in the SDM literature such as variable collinearity and model domain contributed little to differences in SDM performance or predictions in this study. Predictions from different algorithms tended to be more variable at northern range margins for species with more northern distributions, which may complicate conservation planning at the leading edge of species' geographic ranges. The clear message emerging from this work is that researchers should use multiple algorithms for modeling rather than relying on predictions from a single algorithm, invest resources in compiling a comprehensive set of species presences, and explicitly evaluate uncertainty in SDM predictions at leading range margins.

Ecological Modelling↗

USGS1986

Mines and prospects of the Butte 1° x 2° Quadrangle, Montana

The Butte quadrangle, in the Northern Rocky Mountains of southwestern Montana, has had a long, productive, and colorful mining history. Butte, the city from which the quadrangle takes its name, is located in the most famous mining district of the quadrangle. This district, the Butte or Summit Valley district, has been described as the "richest hill on earth" and is one of the richest and most productive mining districts of the world. The quantity of metals produced from this district alone are far greater than the combined total of all commodities from all other mining districts of the quadrangle. However, many districts other than Butte have had significant production as compared to other mining districts of the Northern Rocky Mountains. The dollar value of production from the Butte district is more than $6 billion (Miller, 1973) and that of the combined total of production from the other districts in the quadrangle is more than $400 million. These values are based on actual metal prices at the time of production. The totals would be many times larger if converted to present day commodity prices. Mineral occurrence data for a total of 1111 mines, prospects, and mineral occurrences have been compiled for the Butte quadrangle. These mineralized sites are found throughout the quadrangle but most are concentrated in the major mining districts; 78 percent are clustered in 46 established mining districts and the remaining 22 percent are more widely scattered in 24 geographic areas (fig. 1). Only small areas of the quadrangle lack significant mines, prospects, or mineral occurrences. The locations of mines and prospects are shown on maps (pl. 1 and 2) and a brief description of each site is given in a table arranged by mining district or geographic area (table 1) (all tables are at end of report). This table gives a brief description of each district or area and details of each site within the district or area including site number, name and alternate name(s), location by latitude and longitude, commodities present, description of the site, and sources of data. Data for this report come from the U.S. Geological Survey Mineral Resource Data System (MRDS; this was formerly known as the Computerized Resource Information Bank (CRIB)), from many published and unpublished sources, and from geologic field work. The Butte quadrangle is in southwestern Montana and is bounded by latitudes 46° and 47° N. and longitudes 112° and 114° W. The city of Butte is near the southern edge and in the southeastern corner of the quadrangle. Helena, the state capital of Montana, is located on the eastern edge and Missoula is located near the northwestern corner of the quadrangle. Most of the area of the quadrangle is in Granite, Powell, Lewis and Clark, and Jefferson Counties and the remaining area includes parts of Missoula, Ravalli, Deer Lodge, and Silver Bow Counties. The quadrangle includes a number of major and minor mountain ranges separated by intermontane valleys. The continental divide trends nearly north-south through the eastern part of the quadrangle to a point near Butte, then trends generally east-west near the southern boundary of the quadrangle, west of Butte. East of the divide the drainages are tributary to the Missouri River and west of the divide the drainages are tributary to the Clark Fork, which heads in the vicinity of Butte. The geology of the Butte quadrangle is very complex. Sedimentary and igneous rocks range in age from Proterozoic to Tertiary. Most of the pre-Tertiary sedimentary rocks are structurally complex due to widespread faulting and folding. Due to thrust faulting, complete sequences of these sedimentary units are not generally present in the quadrangle and the thicknesses and lithologies are variable from one thrust plate to another. The oldest rocks in the quadrangle are sedimentary rocks of the Belt Supergroup of Middle Proterozoic age. They form very thick sequences, are exposed over a large percentage of the area of the quadrangle, and include formations of the lower, middle, and upper parts of the Belt. Individual formations are as much as 13,000 ft thick (C. A. Wallace, unpub. data) and the maximum thickness of the Belt Supergroup in the quadrangle may be similar to that of the entire sequence near Alberton, Montana, to the northwest of the Butte quadrangle where it exceeds 67,000 ft (Harrison, 1972). In many areas of the quadrangle these Precambrian rocks are overlain by thin to moderately thick sequences of Cambrian to Permian sedimentary rocks. The maximum thickness of the Paleozoic section is about 8,000 ft (C. A. Wallace, unpub. data). A relatively thick sequence of Mesozoic sedimentary rocks, predominantly Cretaceous in age, which is found mostly in the central part of the quadrangle, overlies the Paleozoic rocks. If complete, the Mesozoic sequence would total about 28,000 ft (C. A. Wallace, unpub. data). The Butte quadrangle is located in a structurally complex region. Most of the Butte quadrangle is in the southern part of the Montana Disturbed Belt, a tectonic belt in the Northern Rocky Mountains characterized by northwest-trending faults and intense deformation. An element of the Disturbed Belt, called the Sapphire Thrust System occupies most of the western two-thirds of the quadrangle. Sedimentary rocks of Cretaceous and older ages in the Sapphire Thrust System have been complexly folded and faulted. Plutonic rocks, which intrude the sedimentary units, and volcanic rocks of Cretaceous and Tertiary ages are widespread in the quadrangle. Most of these are post-thrusting but some may be pre- or syn-tectonic and involved in the thrusting and folding. Most of the mineral wealth in the quadrangle, in the form of hydrothermal ore deposits, is genetically related to Cretaceous granitic plutonism. Igneous activity decreased but continued into Tertiary time, at least until the Oligocene. In the Butte quadrangle the Cenozoic Era was important for normal faulting, volcanism, sedimentation, glaciation, and the formation of many important mineral deposits. Many normal faults were especially active during the Miocene and Pliocene and some were active into the Quaternary. Volcanic rocks of Eocene and Oligocene age cover large areas and are genetically related to several important mining districts. During Cenozoic time, thick accumulations of Tertiary basin-fill sediments, Pleistocene glacial till and outwash, and Holocene alluvium and colluvium were deposited. The Cenozoic was important for the formation of placer deposits valuable mainly for gold but some have produced important quantities of sapphires and tungsten. This map is part of a folio of maps of the Butte 1° x 2°quadrangle, Montana, prepared under the Conterminous United States Mineral Assessment Program (CUSMAP). Other maps to be published as part of this folio are a geologic map, geochemical maps, geophysical maps, maps of linear features and limonitic alteration interpreted from satellite and airborne radar data, and mineral resource assessment maps.

Montana↗

USGS1970

Lower Devonian graptolites from southeastern Alaska

The youngest zones of Monograptus occur in Devonian black shale and slate along the western shore of Prince of Wales Island and on Noyes Island, southeastern Alaska. The following five species of Monograptus , in close association with vascular plants and marine shelly faunas, indicate a Praguian, (Siegenian to Early Emsian), late Lower Devonian and possibly early Middle Devonian age: M. yukonensis Jackson & Lenz, M. n. sp. aff. yukonensis ? Jaeger & Stein, M. aeqimbilis notoaequakilis Jaeger & Stein, M. pacificus Jaeger n. sp. and M. craigensis Jaeger n. sp. The yukonensis zone containing M. craigensis in its upper part is followed stratigraphically higher by the M. pacificus zone – the youngest occurrence of Monograptus. The new species belong to the M. uncinatus group and, like most Praguian monograptids, have long dorsal tongues on their siculae. M. craigensis and M. pacificus increase to seven the number of species of Monograptus known from the Praguian. On the basis of the Alaskan material, the geographical distribution of M. aequabilis notoaequabilis now includes North America in addition to previously recorded occurrences in Australia, Southeast Asia, and Europe. This broad geographic distribution suggests that the last survivors of Monograptus had worldwide distribution and a rather uniform assemblage of species.

Alaska↗

USGS2015

Information resources

During recent decades, natural resources agency personnel and others involved with the management and stewardship of wildlife have experienced an increasing need to access information and obtain technical assistance for addressing a diverse array of wildlife disease issues. This Chapter provides a broad overview of selected sources for obtaining supplemental information and technical assistance for addressing wildlife disease issues in North America. Specifically, examples of existing major wildlife disease programs focusing on free-ranging wildlife populations are highlighted; training opportunities for enhancing within-agency wildlife disease response are identified; a selected reading list of wildlife disease references is provided; and selected Web sites providing timely information on wildlife disease are highlighted. No attempt is made to detail all the North American programs and capabilities that address disease in free-ranging wildlife populations. Instead, this Chapter is focused on enhancing awareness of the types of capabilities that exist as potential sources for assistance and collaboration between wildlife conservation agency personnel and others in addressing wildlife disease issues. A wide variety of entities across North America are involved in wildlife disease investigations; however, the formal assembly of multidimensional programs that primarily address disease for the benefit of free-ranging wildlife is rather limited. The Southeastern Cooperative Wildlife Disease Study (SCWDS), the National Wildlife Health Center (NWHC), and the Canadian Wildlife Health Cooperative (CWHC) are selected examples. These programs are highlighted because of the scope of their capabilities and long-term involvement in assisting State and Federal natural resource agencies combat wildlife disease. A variety of other sources for possible assistance in addressing wildlife disease issues exists throughout North America and globally. It is prudent for wildlife conservation field biologists, managers, and administrators to be aware of such local resources. Ideally, awareness and knowledge of the types of assistance those programs can provide should be obtained prior to disease crisis events since appropriate, timely intervention often is required to minimize wildlife losses from disease and prevent the establishment of new infectious diseases within wildlife populations and geographic areas. Increasing recognition of the substantial number of infectious diseases being transferred between wildlife, domestic animals, and humans has led to increased collaborative investigations between wildlife, domestic, and human health programs. That collaboration has led to a heightened focus on wildlife disease within some public health and agriculture agencies. For purposes of this Chapter, wildlife disease is narrowly defined as those diseases (infectious and noninfectious) causing morbidity and mortality in free-ranging wildlife populations. Therefore, there is no focus on the numerous fish disease or environmental contaminant programs that exist on behalf of North American fauna.

Techniques and Methods↗

USGS2009

Ignoring detailed fast-changing dynamics of land use overestimates regional terrestrial carbon sequestration

Land use change is critical in determining the distribution, magnitude and mechanisms of terrestrial carbon budgets at the local to global scales. To date, almost all regional to global carbon cycle studies are driven by a static land use map or land use change statistics with decadal time intervals. The biases in quantifying carbon exchange between the terrestrial ecosystems and the atmosphere caused by using such land use change information have not been investigated. Here, we used the General Ensemble biogeochemical Modeling System (GEMS), along with consistent and spatially explicit land use change scenarios with different intervals (1 yr, 5 yrs, 10 yrs and static, respectively), to evaluate the impacts of land use change data frequency on estimating regional carbon sequestration in the southeastern United States. Our results indicate that ignoring the detailed fast-changing dynamics of land use can lead to a significant overestimation of carbon uptake by the terrestrial ecosystem. Regional carbon sequestration increased from 0.27 to 0.69, 0.80 and 0.97 Mg C ha −1 yr −1 when land use change data frequency shifting from 1 year to 5 years, 10 years interval and static land use information, respectively. Carbon removal by forest harvesting and prolonged cumulative impacts of historical land use change on carbon cycle accounted for the differences in carbon sequestration between static and dynamic land use change scenarios. The results suggest that it is critical to incorporate the detailed dynamics of land use change into local to global carbon cycle studies. Otherwise, it is impossible to accurately quantify the geographic distributions, magnitudes, and mechanisms of terrestrial carbon sequestration at the local to global scales.

Alabama, Georgia↗

USGS2019

Climate-driven state shifts in the Prairie Pothole Region: Assessing future impacts relevant to the management of wetland habitats critical to waterfowl

Embedded within the North American Prairie Pothole Region (PPR) are millions of small, depressional wetlands that annually support 50–80% of the continent’s waterfowl production. We recently assembled evidence that demonstrates a change towards a wetter climate that is driving a shift in the state of the region’s wetland ecosystems. This ecological state-shift has been primarily the result of a sustained wet climate that has influenced timing and magnitude of surface-water inputs to wetlands, connections to groundwater, and inputs of dissolved salts. As climate influences continue to change in the PPR, it is important to understand the potential of these changes to impact wetland habitats important for waterfowl production. Previous model simulations of prairie-pothole wetlands under future climate scenarios projected decreases in the ability of wetlands to facilitate waterfowl production throughout the majority of what is currently the most productive portion of the region. Results from these modeling efforts also suggested that suitable waterfowl breeding-habitat would be limited mostly to the southeastern portion of the PPR, a portion of the region in which most depressional wetlands (> 90%) have been drained. Thus, if these modeled outcomes materialize, a significant restoration effort would be needed in the southeastern PPR to support waterfowl production. However, the models used in earlier efforts were developed from a small number of wetlands using data from a relatively dry period and did not allow for changing mechanisms influencing surface-water, groundwater and dissolved salt inputs to prairie-pothole wetlands. The primary objective of our research is to improve our understanding of future climate change on impacts to wetland ecosystems and breeding waterfowl habitat in the PPR. We used a newly developed Pothole Hydrology Linked Systems Simulator (PHyLiSS) model to estimate wetland ecosystem responses to 32 distinct climate models under 2 different emissions scenarios. Unlike previous wetland hydrology models, the PHyLiSS model allows for shifting hydrological and geochemical mechanisms influencing wetland ecosystems. We modeled one average-sized seasonal wetland basin at 18 different geographic locations (hereafter “sites”) across the PPR with 3 sites represented for each of 6 ecoregions coincident to early research. We applied the PHyLiSS model using historical daily precipitation and temperature data from 1982–2015 and developed linear models relative to ponded water depth in the simulated wetlands and the observed regional WBPHS May Pond count number for 16 of the 18 sites. Based on the output of 32 climate models and 2 emission scenarios we found a projected change in May pond numbers from -23% to +.02% when comparing the most recent climate period (1989–2018) to the end of the 21 st century (2070–2099). We also found no evidence that the distribution of May ponds will shift in the future. These results suggest that management and conservation strategies for wetlands in the PPR should continue to focus on areas where high densities of intact wetland basins support large numbers of breeding duck pairs.

Alberta, Iowa, Manitoba, Minnesota, Montana, North↗

USGS1983

Preliminary appraisal of the hydrology of the Rock Island area, Le Flore County, Oklahoma

Bed rock in the Rock Island area of northeastern Le Flore County in southeastern Oklahoma consists of shale, siltstone, and sandstone of the McAlester, Hartshorne, and Atoka Formations of Pennsylvanian age. The area is on the south flank of the Backbone anticline; the rocks dip to the south at 5o-45o. Alluvium along James Fork consists of sandy and clayey silt and may be as much as 30 feet thick. Water in bedrock is under artesian conditions. The depth to water in most wells is less than 20 feet below the surface; a few wells flow. Yields of most wells probably are less than 5 gallons per minute. Water from nine wells was a sodium carbonate or sodium mixed anion type; dissolved-solids concentrations ranged from 294 to 1,250 milligrams per liter. No relationship between variations in chemistry of ground water and well depth, geographic distribution, or geologic formation is apparent. James Fork has flow most of the time and discharge exceeds 25 cubic feet per second about one-half the time. The mean dissolved-solids concentration in James Fork water ranged from 224 milligrams per liter near Williams, Oklahoma, to 332 milligrams per liter near Hackett, Arkansas. Water in James Fork is a calcium magnesium sulfate type about 75 percent of the time. Maximum suspended sediment discharge was 2,720 tons per day. Silt-clay particles (diameters less than 0.062 millimeter) are the dominant sediment size. Potential hydrologic effects of surface mining for coal include: (1) Creation of additional water storage in surface-mine ponds, (2) changes in rock permeability and ground-water storage, (3) changes in runoff and streamflow characteristics, (4) changes in drainage patterns, and (5) changes in the chemical quality and sediment load of James Fork. Although mining may increase the quantities of sediment and dissolved minerals added to James Fork, detection of these increases would be difficult because the potentially mineable area is very small in proportion to the total area of the basin.

Water-Resources Investigations Report↗

USGS2015

Gondolellid conodonts and depositional setting of the Phosphoria Formation

The Phosphoria Formation and related rocks were deposited over an 8.9 m.y. interval beginning approximately 274.0Ma and ending approximately 265.1Ma. The Meade Peak Phosphatic Shale Member was deposited in southeastern Idaho and adjacent Wyoming over 5.4 m.y. from approximately 273.2 to 268.6 Ma. The Retort Phosphatic Shale Member was deposited in southwestern Montana and west-central Wyoming over 1.3 m.y. from approximately 267.4 to 266.1Ma. The base of the Roadian Stage of the Middle Permian occurs within the lower phosphate zone of the Meade Peak. The base of the Wordian Stage occurs within the upper phosphate zone of the Meade Peak. The presence of a cool-water brachiopod fauna, cool-water conodont faunas, and the absence of fusulinids throughout the Phosphoria basin indicate the presence of pervasive cool, upwelling waters. Acritarchs are intimately associated with phosphorites and phosphatic shales and may have been the primary organic producer to help drive phosphate production. The gondolellid conodont fauna of the Phosphoria Formation links a geographic cline of Jinogondolella nankingensis from the Delaware basin, West Texas, to the Sverdrup basin, Canadian Arctic, and shows distinct differentiation in species distribution, as do other conodont groups, within the Phosphoria basin. Ten species and two subspecies of gondolellid conodonts are recognized from the Phosphoria Formation and related rocks that belong to Mesogondolella and Jinogondolella.

Montana, Wyoming↗

USGS2021

Embracing ensemble species distribution models to inform at-risk species status assessments

Conservation planning depends on reliable information regarding the geographic distribution of species. However, our knowledge of species' distributions is often incomplete, especially when species are cryptic, difficult to survey, or rare. The use of species distribution models has increased in recent years and proven a valuable tool to evaluate habitat suitability for species. However, practitioners have yet to fully adopt the potential of species distribution models to inform conservation efforts for information-limited species. Here, we describe a species distribution modeling approach for at-risk species that could better inform U.S. Fish and Wildlife Service's species status assessments and help facilitate conservation decisions. We applied four modeling techniques (generalized additive, maximum entropy, generalized boosted, and weighted ensemble) to occurrence data for four at-risk species proposed for listing under the U.S. Endangered Species Act ( Papaipema eryngii, Macbridea caroliniana, Scutellaria ocmulgee, and Balduina atropurpurea ) in the Southeastern United States. The use of ensemble models reduced uncertainty caused by differences among modeling techniques, with a consequent improvement of predictive accuracy of fitted models. Incorporating an ensemble modeling approach into species status assessments and similar frameworks is likely to benefit survey efforts, inform recovery activities, and provide more robust status assessments for at-risk species. We emphasize that co-producing species distribution models in close collaboration with species experts has the potential to provide better calibration data and model refinements, which could ultimately improve reliance and use of model outputs.

Arkansas, Florida, Georgia, Missouri, North Caroli↗

USGS2003

Tidal-bundle sequences in the Jordan Sandstone (Upper Cambrian), southeastern Minnesota, U.S.A.: Evidence for tides along inboard shorelines of the Sauk Epicontinental Sea

This study documents for the first time tidal bundling in a lower Paleozoic sheet sandstone from the cratonic interior of North America, providing insights into the hydrodynamics of ancient epicontinental seas. The Jordan Sandstone (Upper Cambrian) in the Upper Mississippi Valley contains large-scale planar tabular cross-sets with tidal-bundle sequences, which were analyzed in detail at an exceptional exposure. Tidal-bundle sequences (neap-spring-neap cycles) were delineated by foreset thickening-thinning patterns and composite shale drapes, the latter of which represent accumulations of mud during the neap tides of neap-spring-neap tidal cycles. Fourier analysis of the bundle thickness data from the 26 measurable bundle sequences revealed cycles ranging from 15 to 34 bundles per sequence, which suggests a semidiurnal or mixed tidal system along this part of the Late Cambrian shoreline. We extend the tidal interpretation to widespread occurrences of the same facies in outcrops of lesser quality, where the facies is recognizable but too few bundles are exposed for tidal cycles to be measured. By doing so, this study shows that tidally generated deposits have a significant geographic and temporal extent in Upper Cambrian strata of central mid-continent North America. The deposition and preservation of tidal facies was related to the intermittent development of shoreline embayments during transgressions. The tidally dominated deposits filled ravined topographies that were repeatedly developed on the updip parts of the shoreface. Resulting coastal geomorphologies, accompanied perhaps by larger-scale changes in basinal conditions and/or configuration, led to changes in depositional conditions from wave-dominated to tide-dominated. Outcrops of the Jordan Sandstone tidal facies in the Upper Mississippi Valley represent the farthest inboard recorded transmission of ocean-generated tides in the Laurentian epicontinental seas, demonstrating that tidal currents were significant agents in the transport of sand along the far cratonic interior shorelines of Cambrian North America. The results of this study improve the facies-level understanding of the genesis of sheet sandstones. Furthermore, tidalites documented here occur in a specific position within a sequence stratigraphic architecture for the Jordan Sandstone. This provides a framework to compare these ancient deposits and processes to younger (e.g., Carboniferous) epicontinental systems where stratal and sediment dynamics are better documented.

Illinois, Indiana, Iowa, Michigan, Minnesota, Miss↗

USGS1983

Population biology of yellow perch in southern Lake Michigan, 1971-79

This study was based mainly on gill-net collections of yellow perch (Perca flavescens) made during July and August 1971-79, in southern Lake Michigan at Grand Haven, Saugatuck, South Haven, Benton Harbor, and New Buffalo, Michigan; Michigan City and Gary, Indiana; Waukegan, Illinois; and Milwaukee, Wisconsin. Abundance of yellow perch was above the 1971-79 average in 1971 and 1972, below average in 1979, and about average or in doubt in the other years. Abundance during 1976-79 was greatest at Saugatuck and decreased more or less progressively from Saugatuck southward and around the southern end of the lake. The geographical differences in abundance were attributable partly to differences in fishing mortality. Average lengths of fish caught were greatest at Saugatuck, and generally greater in Michigan waters than in other areas; they were greater for females than for males. Fish sampled ranged in age from I to IX, but 88% of the males and 81% of the females were of ages II-V. Older perch were generally more common in State of Michigan waters, particularly at Saugatuck, than elsewhere. Females grew faster than males after the second year of life. Average lengths of males and females at the end of 3 years were 197 and 214 mm, respectively, in Michigan waters and 186 and 195 mm in Indiana-Illinois (few perch were caught in Wisconsin). The relation of weight (W) to length (L) for combined sexes was W = 2.6761(10-6) x L3.2644. Perch in southeastern Lake Michigan spawned mainly from late May to mid June. Virtually all males were mature in their second year, but some females not until their fourth year. Perch 174 to 355 mm long contained 9, 300 to 136, 000 eggs. Approximate mortalities of males and females in Michigan waters were 52% and 48%, respectively; rates were higher in Indiana-Illinois.

Lake Michigan↗