Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Space Weather”

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

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

At least 199 records · Page 11Linked to original sources
USGS2004

Hydrologic scales, cloud variability, remote sensing, and models: Implications for forecasting snowmelt and streamflow

Accurate prediction of available water supply from snowmelt is needed if the myriad of human, environmental, agricultural, and industrial demands for water are to be satisfied, especially given legislatively imposed conditions on its allocation. Robust retrievals of hydrologic basin model variables (e.g., insolation or areal extent of snow cover) provide several advantages over the current operational use of either point measurements or parameterizations to help to meet this requirement. Insolation can be provided at hourly time scales (or better if needed during rapid melt events associated with flooding) and at 1-km spatial resolution. These satellite-based retrievals incorporate the effects of highly variable (both in space and time) and unpredictable cloud cover on estimates of insolation. The insolation estimates are further adjusted for the effects of basin topography using a high- resolution digital elevation model prior to model input. Simulations of two Sierra Nevada rivers in the snowmelt seasons of 1998 and 1999 indicate that even the simplest improvements in modeled insolation can improve snowmelt simulations, with 10%–20% reductions in root-mean-square errors. Direct retrieval of the areal extent of snow cover may mitigate the need to rely entirely on internal calculations of this variable, a reliance that can yield large errors that are difficult to correct until long after the season is complete and that often leads to persistent underestimates or overestimates of the volumes of the water to operational reservoirs. Agencies responsible for accurately predicting available water resources from the melt of snowpack [e.g., both federal (the National Weather Service River Forecast Centers) and state (the California Department of Water Resources)] can benefit by incorporating concepts developed herein into their operational forecasting procedures.

Weather and Forecasting↗
USGS2001

Evaluation of flash-flood discharge forecasts in complex terrain using precipitation

Operational prediction of flash floods produced by thunderstorm (convective) precipitation in mountainous areas requires accurate estimates or predictions of the precipitation distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds are generally small in size, and small position errors in the forecast or observed placement of the precipitation can distribute the rain over the wrong watershed. In addition to the need for good precipitation estimates and predictions, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the precipitation-rate input data. Different techniques for the estimation and prediction of convective precipitation will be applied to the Buffalo Creek, Colorado flash flood of July 1996, where over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the precipitation was exacerbated by the fact that a significant fraction of the watershed experienced a wildfire approximately two months prior to the rain event. Precipitation estimates from the National Weather Service's operational Weather Surveillance Radar-Doppler 1988 and the National Center for Atmospheric Research S-band, research, dual-polarization radar, colocated to the east of Denver, are compared. In addition, very short range forecasts from a convection-resolving dynamic model, which is initialized variationally using the radar reflectivity and Doppler winds, are compared with forecasts from an automated-algorithmic forecast system that also employs the radar data. The radar estimates of rain rate, and the two forecasting systems that employ the radar data, have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the radar data and forecasts from the dynamic model and the automated algorithm could be operationally useful for input to surface-hydrologic models employed for flood warning. Precipitation data provided by these various techniques at short time scales and at fine spatial resolutions are employed as detailed input to a distributed-parameter hydrologic model for flash-flood prediction and analysis. With the radar-based precipitation estimates employed as input, the simulated flood discharge was similar to that observed. The dynamic-model precipitation forecast showed the most promise in providing a significant discharge-forecast lead time. The algorithmic system's precipitation forecast did not demonstrate as much skill, but the associated discharge forecast would still have been sufficient to have provided an alert of impending flood danger.

Journal of Hydrologic Engineering↗
USGS2011

River chemistry as a monitor of Yosemite Park mountain hydroclimates

High-frequency, high-altitude measurements of water chemistry provide insights into processes relating to the hydrology, climate, and geochemistry of mountain catchments. When such observations are combined with stream stage, temperature, snow, weather, and other surface hydroclimate measurements, they are particularly useful in allowing connections between climate, river discharge, river chemistry, and ecosystems to be discerned. Climate is the major source of variability in U.S. and global water resources. For example, large-scale variations in the global atmosphere and the Pacific Ocean are responsible for much of the variability in river discharge in Hawaii, Alaska, the U.S. Pacific Northwest, and the U.S. Southwest [ Cayan and Peterson , 1989], and thus are closely linked to water and energy resources of the western United States [ Cayan et al ., 2003].

Eos, Earth and Space Science News↗
USGS2016

Ungulate reproductive parameters track satellite observations of plant phenology across latitude and climatological regimes

The effect of climatically-driven plant phenology on mammalian reproduction is one key to predicting species-specific demographic responses to climate change. Large ungulates face their greatest energetic demands from the later stages of pregnancy through weaning, and so in seasonal environments parturition dates should match periods of high primary productivity. Interannual variation in weather influences the quality and timing of forage availability, which can influence neonatal survival. Here, we evaluated macro-scale patterns in reproductive performance of a widely distributed ungulate (mule deer, Odocoileus hemionus ) across contrasting climatological regimes using satellite-derived indices of primary productivity and plant phenology over eight degrees of latitude (890 km) in the American Southwest. The dataset comprised > 180,000 animal observations taken from 54 populations over eight years (2004–2011). Regionally, both the start and peak of growing season (“Start” and “Peak”, respectively) are negatively and significantly correlated with latitude, an unusual pattern stemming from a change in the dominance of spring snowmelt in the north to the influence of the North American Monsoon in the south. Corresponding to the timing and variation in both the Start and Peak, mule deer reproduction was latest, lowest, and most variable at lower latitudes where plant phenology is timed to the onset of monsoonal moisture. Parturition dates closely tracked the growing season across space, lagging behind the Start and preceding the Peak by 27 and 23 days, respectively. Mean juvenile production increased, and variation decreased, with increasing latitude. Temporally, juvenile production was best predicted by primary productivity during summer, which encompassed late pregnancy, parturition, and early lactation. Our findings offer a parsimonious explanation of two key reproductive parameters in ungulate demography, timing of parturition and mean annual production, across latitude and changing climatological regimes. Practically, this demonstrates the potential for broad-scale modeling of couplings between climate, plant phenology, and animal populations using space-borne observations.

Arizona, Colorado, Utah↗
USGS2013

Spectroscopic remote sensing of the distribution and persistence of oil from the Deepwater Horizon spill in Barataria Bay marshes

We applied a spectroscopic analysis to Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) data collected from low and medium altitudes during and after the Deepwater Horizon oil spill to delineate the distribution of oil-damaged canopies in the marshes of Barataria Bay, Louisiana. Spectral feature analysis compared the AVIRIS data to reference spectra of oiled marsh by using absorption features centered near 1.7 and 2.3 μm, which arise from CH bonds in oil. AVIRIS-derived maps of oiled shorelines from the individual dates of July 31, September 14, and October 4, 2010, were 89.3%, 89.8%, and 90.6% accurate, respectively. A composite map at 3.5 m grid spacing, accumulated from the three dates, was 93.4% accurate in detecting oiled shorelines. The composite map had 100% accuracy for detecting damaged plant canopy in oiled areas that extended more than 1.2 m into the marsh. Spatial resampling of the AVIRIS data to 30 m reduced the accuracy to 73.6% overall. However, detection accuracy remained high for oiled canopies that extended more than 4 m into the marsh (23 of 28 field reference points with oil were detected). Spectral resampling of the 3.5 m AVIRIS data to Landsat Enhanced Thematic Mapper (ETM) spectral response greatly reduced the detection of oil spectral signatures. With spatial resampling of simulated Landsat ETM data to 30 m, oil signatures were not detected. Overall, ~ 40 km of coastline, marsh comprised mainly of Spartina alterniflora and Juncus roemerianus, were found to be oiled in narrow zones at the shorelines. Zones of oiled canopies reached on average 11 m into the marsh, with a maximum reach of 21 m. The field and airborne data showed that, in many areas, weathered oil persisted in the marsh from the first field survey, July 10, to the latest airborne survey, October 4, 2010. The results demonstrate the applicability of high spatial resolution imaging spectrometer data to identifying contaminants in the environment for use in evaluating ecosystem disturbance and response.

Louisiana↗
USGS2020

Population ecology and spatial synchrony in abundance within and among populations of valley oak (Quercus lobata) leaf gall wasps

What factors drive population variability through space and time? Here we assess patterns of abundance of seven species of gall wasps in three genera occurring on the leaves of valley oaks ( Quercus lobata ) at 10 sites throughout this species' statewide range in California, from 2000 to 2006. Our primary goals were to understand the factors driving variability in gall abundance and to assess the extent of spatial synchrony in gall wasp communities at both large and small geographic scales. On the large, statewide scale, there was significant site‐to‐site variation in gall abundance, driven in all cases primarily by differences in mean maximum seasonal temperatures, and lesser year‐to‐year variation. In contrast, on the small, local scale, differences were more pronounced from year to year than from tree to tree, and were to some extent correlated with differences in acorn production, suggesting an interaction with the reproductive effort of hosts. Significant spatial synchrony was detected, particularly at the statewide scale, but in no case did synchrony decline significantly with distance, despite sites being up to 741 km apart. Variation in spatial synchrony was correlated with a number of exogenous factors, including seasonal weather conditions, the acorn crop at the statewide scale and soil phosphorus availability at the local scale; however, most variation in spatial synchrony in our analyses remained unexplained.

California↗
USGS1998

Terrestrial sedimentation and the carbon cycle: Coupling weathering and erosion to carbon burial

This paper examines the linkages between the carbon cycle and sedimentary processes on land. Available data suggest that sedimentation on land can bury vast quantities of organic carbon, roughly 10 15 g C yr −1 . To evaluate the relative roles of various classes of processes in the burial of carbon on land, terrestrial sedimentation was modeled as a series of 864 scenarios. Each scenario represents a unique choice of intensities for seven classes of processes and two different global wetland distributions. Comparison was made with presumed preagricultural conditions. The classes of processes were divided into two major component parts: clastic sedimentation of soil-derived carbon and organic sedimentation of autochthonous carbon. For clastic sedimentation, masses of sediment were considered for burial as reservoir sediment, lake sediment, and combined colluvium, alluvium, and aeolian deposits. When the ensemble of models is examined, the human-induced burial of 0.6-1.5·10 15 g yr −1 of carbon on land is entirely plausible. This sink reaches its maximum strength between 30° and 50° N. Paddy lands stand out as a type of land use that warrants future study, but the many faces of rice agriculture limit generalization. In an extreme scenario, paddy lands alone could be made to bury about 1·10 15 g C yr −1 . Arguing that terrestrial sedimentation processes could be much of the sink for the so called “missing carbon” is reasonable. Such a hypothesis, however, requires major redesign of how the carbon cycle is modeled. Unlike ecosystem processes that are amenable to satellite monitoring and parallel modeling, many aspects of terrestrial sedimentation are hidden from space.

Global Biogeochemical Cycles↗
USGS2001

Acidic deposition in the northeastern United States: Sources and inputs, ecosystem effects, and management strategies: The effects of acidic deposition in the northeastern United States include the acidification of soil and water, which stresses terrestrial and aquatic biota

Acidic deposition is the transfer of strong acids and acid-forming substances from the atmosphere to the surface of the Earth. The composition of acidic deposition includes ions, gases, and particles derived from the following: gaseous emissions of sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), ammonia (NH 3 ), and particulate emissions of acidifying and neutralizing compounds. Over the past quarter century of study, acidic deposition has emerged as a critical environmental stress that affects forested landscapes and aquatic ecosystems in North America, Europe, and Asia. This complex problem is an example of a new class of environmental issues that are multiregional in scale and are not amenable to simple resolution by policymakers. Acidic deposition can originate from transboundary air pollution and can affect large geographic areas. It is highly variable across space and time, links air pollution to diverse terrestrial and aquatic ecosystems, and alters the interactions of many elements (e.g., sulfur [S], nitrogen [N], hydrogen ion [H + ], calcium [Ca 2+ ], magnesium [Mg 2+ ], and aluminum [Al]). It also contributes directly and indirectly to biological stress and to the degradation of ecosystems. Despite the complexity of the effects of acidic deposition, North American and European management actions directed toward the recovery of damaged natural resources have resulted in recent decreases in both emissions and deposition of acidic S compounds. Accordingly, acidic deposition presents an instructive case study for coordinating science and policy efforts aimed at resolving large-scale environmental problems.

northeastern United States↗
USGS2019

Validating a time series of annual grass percent cover in the sagebrush ecosystem

We mapped yearly (2000–2016) estimates of annual grass percent cover for much of the sagebrush ecosystem of the western United States using remotely sensed, climate, and geophysical data in regression-tree models. Annual grasses senesce and cure by early summer and then become beds of fine fuel that easily ignite and spread fire through rangeland systems. Our annual maps estimate the extent of these fuels and can serve as a tool to assist land managers and scientists in understanding the ecosystem’s response to weather variations, disturbances, and management. Validating the time series of annual maps is important for determining the usefulness of the data. To validate these maps, we compare Bureau of Land Management Assessment Inventory and Monitoring (AIM) data to mapped estimates and use a leave-one-out spatial assessment technique that is effective for validating maps that cover broad geographical extents. We hypothesize that the time series of annual maps exhibits high spatiotemporal variability because precipitation is highly variable in arid and semiarid environments where sagebrush is native, and invasive annual grasses respond to precipitation. The remotely sensed data that help drive our regression-tree model effectively measures annual grasses’ response to precipitation. The mean absolute error (MAE) rate varied depending on the validation data and technique used for comparison. The AIM plot data and our maps had substantial spatial incongruence, but despite this, the MAE rate for the assessment equaled 12.62%. The leave-one-out accuracy assessment had an MAE of 8.43%. We quantified bias, and bias was more substantial at higher percent cover. These annual maps can help management identify actions that may alleviate the current cycle of invasive grasses because it enables the assessment of the variability of annual grass − percent cover distribution through space and time, as part of dynamic systems rather than static systems.

Rangeland Ecology and Management↗
USGS2001

Quaternary glacial, lacustrine, and fluvial interactions in the western Noatak basin, Northwest Alaska

The 130 km long Noatak basin is surrounded by mountains of the western Brooks Range. Middle and late Pleistocene glaciers flowing southeast into the basin dammed a succession of proglacial lakes defined by shorelines, outlet channels, and upper limits of wave erosion. More than 60 bluffs along the Noatak River and its principal tributaries expose glacial and glaciolacustrine sediments that exhibit cut-and-fill relationships with interglacial and interstadial river-channel and floodplain deposits. This report focuses on the western Noatak basin, where high bluffs created by deep postglacial erosion record four major glacial advances. During the Cutler advance, a floating ice tongue terminated in a large proglacial lake that filled the Noatak basin. The retreating glacier abandoned a trough along the valley center that subsequently filled with about 40 m of sediment during several younger glaciations and probably two major interglacial episodes. Alluvium that formed near the beginning of the younger interglaciation contains the 140,000 yr old Old Crow tephra. The subsequent closely spaced Okak and Makpik advances are clearly younger than the maximum of the last interglaciation, but they preceded a middle Wisconsin (36-30 ka) nonglacial interval in the Noatak basin. The Okak advance terminated in an extensive lake, whereas glaciers of the Makpik and the subsequent Anisak advances flowed into much narrower lakes that filled only the basin center. The Anisak advance, bracketed by radiocarbon ages of about 35 and 13.6 ka, represents the Last Glacial Maximum (LGM) in the western Noatak basin. Correlations with the oldest and youngest glacial deposits of the central Brooks Range are clear, but relationships to events of intermediate age are more tenuous. Early Pleistocene and older glacial advances from the central Brooks Range must have filled the Noatak basin and overflowed northward through Howard Pass. A younger glacial advance, of inferred middle Pleistocene (Sagavanirktok River) age, extended down the Noatak valley into the basin center, but its deposits are deeply buried beneath the basin floor and must be older than the Cutler moraine. The Cutler advance may have been synchronous with the older of two advances of Itkillik I age in the Atongarak Creek area, but other evidence indicates that the Okak-Makpik moraine succession more likely was synchronous with the two Atongarak Creek moraines. Radiocarbon ages, surface morphology, soil and weathering profiles, and lake-level history all support correlation of the last (Anisak) major glacial advance in the western basin with the Douglas Creek moraine farther east and with Itkillik II (late Wisconsin) glaciation of the central Brooks Range.

Alaska↗
USGS2016

Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam, Arizona

This study examined links among fluvial, aeolian, and hillslope geomorphic processes that affect archeological sites and surrounding landscapes in the Colorado River corridor downstream from Glen Canyon Dam, Arizona. We assessed the potential for Colorado River sediment to enhance the preservation of river-corridor archeological resources through aeolian sand deposition or mitigation of gully erosion. By identifying locally prevailing wind directions, locations of modern sandbars, and likely aeolian-transport barriers, we determined that relatively few archeological sites are now ideally situated to receive aeolian sand supply from sandbars deposited by recent controlled floods. Whereas three-fourths of the 358 river-corridor archeological sites we examined include Colorado River sediment as an integral component of their geomorphic context, only 32 sites currently appear to have a high degree of connectivity (coupled interactions) between modern fluvial sandbars and sand-dominated landscapes downwind. This represents a substantial decrease from past decades, as determined by aerial-photograph analysis. Thus, we infer that recent controlled floods have had a limited, and declining, influence on archeological-site preservation. Within the study area, overland-flow (gully) erosion is less severe in sand landscapes with active aeolian sand than in landscapes that lack aeolian transport; gullies terminate more commonly in active sand (sand that is mobile by wind rather than stabilized by biologic soil crust). We infer that these characteristics largely result from aeolian sand transport being an effective gully-limiting and gully-annealing mechanism. Aeolian sand activity in the river corridor varies substantially as a function of reach morphology and dominant wind direction relative to the river-corridor orientation, factors that control accommodation space for river-derived sand and the modern sand supply to aeolian dunes. These attributes, together with an inverse correlation between aeolian sand activity and gully occurrence, define varying degrees of net long-term gully-erosion risk for sediment deposits and associated archeological sites in different regions of the river corridor. Over most of the river corridor, including some of the archeologically richest regions, sand is too inactive with respect to aeolian transport to anneal gullies effectively. At eight selected archeological sites that we studied with high-resolution terrestrial lidar scans for more than a year, sand loss by overland flow (gully erosion) and aeolian deflation generally exceeded deposition, such that erosion dominated over most monitoring intervals—even at four sites with strong connectivity to modern sand supply. The Glen Canyon reach of the river corridor appears especially vulnerable to gully erosion. Among the sites that we monitored in detail, erosion generally dominated over deposition to a greater degree at four Glen Canyon sites with no modern sand supply than at four Marble–Grand Canyon sites with aeolian sand supply from controlled-flood sandbars. Although gross annual-scale erosion rates were similar among the Glen Canyon sites and among the Marble–Grand Canyon sites, a relative lack of depositional processes led to greater net erosion at the Glen Canyon sites. Having found no differences in weather patterns to suggest greater erosive forcing in Glen Canyon, and no conclusively influential differences in the slope or watershed area contributing to gully formation, we attribute the greater erosion at the Glen Canyon sites to a combination of inherent geomorphic context (high terraces that do not receive modern sediment supply) and pronounced effects of postdam sediment-supply limitation. We conclude that most of the river-corridor archeological sites are at elevated risk of net erosion under present dam operations. In the present flow regime, controlled floods do not simulate the magnitude or frequency of natural floods, and are not large enough to deposit sand at elevations that were flooded at annual to decadal intervals in predam time. For archeological sites that depend upon river-derived sand, we infer elevated erosion risk owing to a combination of reduced sand supply (both fluvial and aeolian) through (1) the lower-than-natural flood magnitude, frequency, and sediment supply of the controlled-flooding protocol; (2) reduction of open, dry sand area available for wind redistribution under current normal (nonflood) dam operations, which do not include flows as low as natural seasonal low flows and do include substantial daily flow fluctuations; and (3) impeded aeolian sand entrainment and transport owing to increased riparian vegetation growth in the absence of larger, more-frequent floods. If dam operations were to increase the supply of sand available for windblown transport—for example, through larger floods, sediment augmentation, or increased fluvial sandbar exposure by low flows—and also decrease riparian vegetation, the prevalence of active aeolian sand could increase over time, and the propensity for unmitigated gully erosion could decrease. Although the evolution of river-corridor landscapes and archeological sites has been altered fundamentally by the lack of large, sediment-rich floods (flows on the order of 5,000 m 3 /s), some combination of sediment-rich flows above 1,270 m 3 /s, seasonal flows below 226 m 3 /s, and riparian-vegetation removal might increase the preservation potential for sand-dependent archeological resources in the Colorado River corridor.

Arizona↗
USGS1949

Populations and home range relationships of the box turtle, Terrapene carolina (Linnaeus)

A population study of Terrapene carolina (Linnaeus) was made at the Patuxent Research Refuge, Maryland, from 1944 to 1947. A thirty acre area in bottomland forest was selected for intensive study. Turtles were marked by filing notches in marginal scutes according to a code. Turtles make extensive use of brushy shelter during the day as well.as at night. Gully banks and woods openings are used for sunning. Nights are usually spent in a 'form,' constructed by the turtle in leaves, debris, or earth. A form may be used once or it may be used repeatedly by the same or different turtles. Weather conditions most favorable to turtle activity are high humidity, warm sunny days, and frequent rains. Periods of activity are alternated with periods of quiet, even in favorable weather. There is no evidence for territorialism. Ranges of turtles of all ages and both sexes overlap grossly. Turtles are frequently found near each other but no antagonistic behavior has been observed. Adult turtles occupy specific home ranges which they maintain from year to year. Turtles retained their ranges even though a flood that completely covered the study area. Maximum home range diameters were determined by measurements of the mapped ranges of individual turtles. There was no significant difference between sizes of male and female ranges: males 33O+ 26 feet, females 37O+29 feet. A trail-laying device was used in following travel routes for 456 turtle days. Normal movements within the home range are characterized by (1) turns, doublings, detours, and criss-crossing paths, (2) interspersion of fairly direct traverses of the home range, (3) frequently repeated travels over certain routes. Maximum limits of the home range are ordinarily reached within a few days or weeks, although some turtles cover only one portion of the range at a time. Some turtles have two home ranges. One of these turtles was followed with a trailer for 161 days in 1946 and 1947. Trips outside the home range are made by females for egg laying. Trips of unexplained nature are made by both males and females. Turtles from other areas are occasional transients through the study plot. Standardized census trips provided data for estimating the size of the population. Census data were taken after females had returned from egg laying. The samples were spaced at intervals of a week or more to allow free movement of turtles over their ranges and assure more nearly equal availability of all turtles. These standard samples were compared by a collection ratio. Assumptions involved in the use of this ratio are discussed. Correction factors were applied to make allowance for turtles whose ranges.were partly inside and partly outside the study area, and for transient turtles. A second estimate, on the basis of the entire season's collecting, gave closely comparable results. The population of the study area is estimated to be between four and five turtles per acre, with juveniles constituting less than ten per cent of the total.

Dissertation Abstracts International↗
USGS2008

Lithofacies, Age, and Sequence Stratigraphy of the Carboniferous Lisburne Group in the Skimo Creek Area, Central Brooks Range

The Lisburne Group, a mainly Carboniferous carbonate succession that is widely distributed across northern Alaska, contains notable amounts of oil and gas at Prudhoe Bay. Detailed studies of the Lisburne in the Skimo Creek area, central Brooks Range, delineate its lithofacies, age, conodont biofacies, depositional environments, and sequence stratigraphy and provide new data on its hydrocarbon source-rock and reservoir potential, as well as its thermal history, in this area. We have studied the Lisburne Group in two thrust sheets of the Endicott Mountains allochthon, herein called the Skimo and Tiglukpuk thrust sheets. The southern, Skimo Creek section, which is >900 m thick, is composed largely of even-bedded to nodular lime mudstone and wackestone intercalated with intervals of thin- to thick-bedded bioclastic packstone and grainstone. Some parts of the section are partially to completely dolomitized and (or) replaced by chert. A distinctive, 30-m-thick zone of black, organic-rich shale, lime mudstone, and phosphorite is exposed 170 m below the top of the Lisburne. The uppermost 40 m of section is also distinctive and made up of dark shale, lime mudstone, spiculite, and glauconitic grainstone. The northern, Tiglukpuk Creek section, which is similar to the Skimo Creek section but only ~760 m thick, includes more packstone and grainstone and less organic-rich shale. Analyses of conodonts and foraminifers indicate that both sections range in age from late Early Mississippian (Osagean) through Early Pennsylvanian (early Morrowan) and document a hiatus of at least 15 m.y. at the contact between the Lisburne and the overlying Siksikpuk Formation. No evidence of subaerial exposure was observed along this contact, which may represent a submarine erosional surface. Lithofacies and biofacies imply that the Lisburne Group in the study area was deposited mainly in midramp to outer-ramp settings. Deepest water strata are mud rich and formed below storm or fair-weather wave base on the outer ramp to outer midramp; shallowest facies are storm, sand-wave, and shoal deposits of the inner midramp to inner ramp. A relatively diverse, open-marine fauna occurs throughout much of the Lisburne in the study area, but some beds also contain clasts typical of more restricted, shallow-water environments that were likely transported seaward by storms and currents. Radiolarians are abundant in the shale and phosphorite unit at Skimo Creek and also occur in equivalent strata at Tiglukpuk Creek; high gamma-ray response and elevated total organic-carbon contents (max 5?8 weight percent) also characterize this unit at Skimo Creek. Lithologic, faunal, and geochemical data all suggest that these rocks formed mainly in an outer-ramp to basinal setting with low sedimentation rates, high productivity, and poorly oxygenated bottom water. Shale and mudstone at the top of the Lisburne Group accumulated in a similarly sediment starved, mainly outer ramp environment but lack comparable evidence for high nutrient and low oxygen levels during deposition. Vertical shifts in rock types and faunas delineate numerous parasequences and six probable third-order sequences in the study area; the same sequences are also recognized in the Lisburne Group to the east. Transgressive-system tracts in these sequences generally fine upward, whereas highstand-system tracts coarsen upward. Sequences in the Tiglukpuk Creek section are mostly thinner, contain thinner and more numerous parasequences, and accumulated in somewhat shallower settings than those in the Skimo Creek section. These differences reflect the more seaward position and, thus, increased accommodation space of the Skimo Creek section relative to the Tiglukpuk Creek section during deposition. Organic-rich calcareous shale in the shale and phosphorite unit has a cumulative thickness of at least 15 m and a lateral extent of >50 km; this lithology is the best potential hydrocarbon source rock in the Lisburne Group

Professional Paper↗
USGS2011

Ant-nest ichnofossils in honeycomb calcretes, Neogene Ogallala Formation, High Plains region of western Kansas, U.S.A.

Two new ant-nest trace fossils are described from calcic sandy paleosols of the Neogene Ogallala Formation in western Kansas. The ichnofossils are preserved within and below calcrete beds weathering in positive relief as carbonate-filled casts or as cavities in negative relief. Daimoniobarax ichnogenus nov. is established for burrow systems composed of vertically tiered, horizontally oriented pancake-shaped chambers connected by predominantly vertical and cylindrical shafts ~ 0.8 cm in diameter. Ichnospecies of Daimoniobarax are differentiated based on differences in the plan view outline of chambers, shaft orientation, and junctions between chambers and shafts. Daimoniobarax nephroides ichnospecies nov. is composed of an ~ 24–76 cm long vertical sequence of distinctly lobed chambers (~ 2–20 cm wide and ~ 1 cm high) arranged along sinuous to helical shafts. Chamber shape in plan view ranges from small teardrops to larger kidney- and U-shaped forms. Shafts intersect at chamber edges such that chambers appear to bud from the central shafts. Daimoniobarax nephroides is most similar to the nests of extant seed-harvester ants of the New World genus Pogonomyrmex . Such ants are specialized granivores and prefer sandy soils in arid to semi-arid grassland and desert regions. Daimoniobarax tschinkeli ichnospecies nov. is ~ 30–80 cm in vertical extent. Chambers (~ 2–30 cm wide and ~ 1 cm high) are circular to elongate or pseudopodial in plan view. Vertical shafts are straight to slightly sinuous and intersect most often toward the center of the chambers. The generalized architecture of D. tschinkeli is similar to that of the nests or nest portions of several extant ant genera, though it does not closely resemble any known modern nest. Ant ichnofossils provide valuable information on hidden biodiversity, paleohydrologic regimes, paleopedogenic processes, and paleoclimate during the time of nest occupation. Depth-related changes in chamber size and vertical spacing may also help interpret paleosurfaces and paleodepths, and serve as geopetal features.

Kansas↗
USGS2022

Medium spatial resolution mapping of global land cover and land cover change across multiple decades from Landsat

Land cover maps are essential for characterizing the biophysical properties of the Earth’s land areas. Because land cover information synthesizes a rich array of information related to both the ecological condition of land areas and their exploitation by humans, they are widely used for basic and applied research that requires information related to land surface properties (e.g., terrestrial carbon models, water balance models, weather, and climate models) and are core inputs to models and analyses used by natural resource scientists and land managers. As the Earth’s global population has grown over the last several decades rates of land cover change have increased dramatically, with enormous impacts on ecosystem services (e.g., biodiversity, water supply, carbon sequestration, etc.). Hence, accurate information related to land cover is essential for both managing natural resources and for understanding society’s ecological, biophysical, and resource management footprint. To address the need for high-quality land cover information we are using the global record of Landsat observations to compile annual maps of global land cover from 2001 to 2020 at 30 m spatial resolution. To create these maps we use features derived from time series of Landsat imagery in combination with ancillary geospatial data and a large database of training sites to classify land cover at annual time step. The algorithm that we apply uses temporal segmentation to identify periods with stable land cover that are separated by breakpoints in the time series. Here we provide an overview of the methods and data sets we are using to create global maps of land cover. We describe the algorithms used to create these maps and the core land cover data sets that we are creating through this effort, and we summarize our approach to accuracy assessment. We also present a synthesis of early results and discuss the strengths and weaknesses of our early map products and the challenges that we have encountered in creating global land cover data sets from Landsat. Initial accuracy assessment for North America shows good overall accuracy (77.0 ± 2.0% correctly classified) and 79.8% agreement with the European Space Agency (ESA) WorldCover product. The land cover mapping results we report provide the foundation for robust, repeatable, and accurate mapping of global land cover and land cover change across multiple decades at 30 m spatial resolution from Landsat.

Frontiers in Remote Sensing↗
USGS2013

Numerical simulation of the groundwater-flow system in Chimacum Creek Basin and vicinity, Jefferson County, Washington

A groundwater-flow model was developed to evaluate potential future effects of growth and of water-management strategies on water resources in the Chimacum Creek Basin. The model covers an area of about 64 square miles (mi 2 ) on the Olympic Peninsula in northeastern Jefferson County, Washington. The Chimacum Creek Basin drains an area of about 53 mi 2 and consists of Chimacum Creek and its tributary East Fork Chimacum Creek, which converge near the town of Chimacum and discharge to Port Townsend Bay near the town of Irondale. The topography of the model area consists of north-south oriented, narrow, regularly spaced parallel ridges and valleys that are characteristic of fluted glaciated surfaces. Thick accumulations of peat occur along the axis of East Fork Chimacum Creek and provide rich soils for agricultural use. The study area is underlain by a north-thickening sequence of unconsolidated glacial (till and outwash) and interglacial (fluvial and lacustrine) deposits, and sedimentary and igneous bedrock units that crop out along the margins and the western interior of the model area. Six hydrogeologic units in the model area form the basis of the groundwater-flow model. They are represented by model layers UC (upper confining), UA (upper aquifer), MC (middle confining), LA (lower aquifer), LC (lower confining), and OE (bedrock). Groundwater flow in the Chimacum Creek Basin and vicinity was simulated using the groundwater-flow model, MODFLOW-2005. The finite-difference model grid comprises 245 columns, 313 rows, and 6 layers. Each model cell has a horizontal dimension of 200 × 200 feet (ft). The thickness of model layers varies throughout the model area and ranges from 5 ft in the non-bedrock units to more than 2,400 ft in the bedrock. Groundwater flow was simulated for steady-state conditions, which were simulated for calibration of the model using average recharge, discharge, and water levels for the 180-month period October 1994–September 2009. The model as calibrated has a mean residual of 4.5 ft and a standard error on the mean of 2.1 ft for heads, and 0.64±0.42 cubic feet per second for streamflows. After the model was calibrated, a Current Conditions simulation was developed to reflect current (October 2008–September 2009) hydrologic conditions, with representative pumping, return flows, and “normal” recharge (based on National Weather Service average precipitation for 1981 to 2010). The Current Conditions simulation was used to estimate current flow quantities, and as a basis to compare other simulations.Simulated steady-state inflow to the model area from precipitation and secondary recharge, or “return flow,” was 16,347 acre-feet per year (acre-ft/yr); groundwater inflow from other basins to the north of the model boundary was 1,518 acre-ft/yr (net, 3,114 acre-ft/yr in and 1,596 acre-ft/yr out) and simulated inflow from lake leakage was 613 acre-ft/yr (net, 684 acre-ft/yr in and 71 acre-ft/yr out). Simulated outflow from the model primarily was through discharge to Puget Sound (10,022 acre-ft/yr), streams (5,424 acre-ft/yr ), springs and seeps (1,521 acre-ft/yr), and through withdrawals from wells (1,506 acre-ft/yr). Four simulations were formulated using the calibrated model—one to represent current conditions (2009, the end of the period used for calibration) and three to provide representative examples of how the model can be used to evaluate the relative effects of potential changes in groundwater withdrawals and consumptive use on groundwater levels and stream base flows: Probable Future Use, based on population projections; Full Beneficial Use, based on Jefferson County Public Utility District #1 water rights; Sanitary Sewer, based on eliminating septic return flows in the Urban Growth Area. Particle tracking was used to assess flowpaths from sources and to sinks, and the effects of the presence of irrigation wells and their depths was assessed.

Washington↗
USGS2024

Global survey of paleo-bedforms on Mars

Sedimentary processes on Mars have contributed to a plethora of landforms, both ancient and modern. Many of these are aeolian- or fluvial-formed constructs that meet the morphologic criteria for dunes and ripples but are clearly lithified and part of the rock record. This study conducted a survey of Mars using data returned from the High Resolution Imaging Science Experiment (HiRISE) to characterize the spatial distribution, origin, and geologic context of these preserved ancient bedforms, termed here as paleo-bedforms. The most compelling class include organized groups of 2–80-m-tall, crescentic to transverse features spaced at 100–1000 m wavelengths at Apollinaris Sulci, Valles Marineris, and other low-latitude sites. These morphologies along with superposed craters, boulders, and fractures led to the interpretation that these are highly lithified, friable, and partially eroded ancient aeolian dunes. In addition to lithified dunes, other remnants of ancient bedforms include examples in which the dune was completely removed, leaving a shallow depression in a crescentic outline as dune cast pits. The most widespread occurrences of paleo-bedforms show crest-to-crest wavelengths (10–80 m), heights (∼1–4 m), and morphologies consistent with lower-order bedforms of megaripples or transverse aeolian ridges. Paleo-megaripple fields in Arcadia Planitia, Hellas Planitia, Terra Sirenum, and other locations exhibit a progression of degraded morphologies, with crests showing signs of rounding, pitting, or fracturing, while heights and slopes are diminished due to erosion. Most rare are the paleo-bedforms in the fluvial bedform class at Lethe Vallis and Holden crater, as they occur along the path of proposed ancient flooding events. More enigmatic paleo-bedform candidates occur concentrated along the steep Valles Marineris and Noctis Labyrinthus wall slopes. These intermediate-sized, arcuate landforms that resemble transverse climbing dunes are heavily cratered, but they may align perpendicular or oblique to the local gradient, perhaps formed by wall slope winds and slope creep. The bedforms are unlike most ancient terrestrial aeolian or fluvial bedform systems, which are typically preserved only as truncated members of stratigraphic sections. Episodes of burial and exhumation by various geologic units (e.g., the Medusae Fossae Formation, pyroclastic units, lava flows, dust) are notable, whereas other bedforms appear to have been stabilized and partially lithified in place without burial. Ongoing agents of mass wasting, aeolian abrasion, and cryo-driven processes have contributed to the exhumation, erosion, and weathered appearance of paleo-bedforms, and a spectrum of degradation states was observed. Collectively, we report a diverse variety of ancient sedimentary bedforms preserved across Mars, with implications about paleoclimates and landscape evolution on Mars.

Geomorphology↗
USGS2018

Delindeite titanosilicates and lourenswalsite, two new from the Magnet Cove region, Arkansas

Delindeite and lourenswalsite are two new barium titanosilicate minerals found as microscopic crystals in miarolitic cavities in nepheline syenite in the Diamond Jo quarry, Hot Spring County, Arkansas. Delindeite is found as aggregates of flake-like crystallites in compact spherules, light pinkish grey in colour, with a resinous, pearly lustre. The flakes are biaxial positive with average n ∼ 1.813; the measured density is 3.3 g/cm 3 . Electron diffraction revealed a monoclinic unit cell in space group C 2 l m or subgroup, with a = 21.617(13), b = 6.816(5), c = 5.383(3) Å, β = 94.03(5)° (refined from X-ray powder data). The strongest X-ray lines are ( hkl , d obs , I rel ): (200, 10.80, 100); (311, 3.54, 24); (6̄01, 3.083, 28); (601, 2.888, 31); (2̄21, 2.806, 20); (910, 2.262,18). The crystals are submicroscopically twinned on (100) and also produce additional continuous diffraction streaks parallel to a *, which double the b and c axes. The formula derived from electron and ion probe analyses (H 2 O by difference), as constrained by density and molar volume data, is approximately (Na,K) 2.7 (Ba,Ca) 4 (Ti,Fe,Al) 6 Si 8 O 26 (OH) 14 , with Na > K, Ba ≫ Ca, Ti ≫ Fe,Al; Z = 1. Lourenswalsite occurs as very thin hexagonal plates in rosettes, silver grey to light brownish grey in colour. The crystals are biaxial negative with very low 2 V angle. Indices of refraction are n α = 1.815, n β ≈ n γ = 1.840; the measured density is 3.17 g/cm = 1.840; the measured density is 3.17 g/cm 3 . X-ray and electron diffraction show a sharp pseudohexagonal lattice with a = 5.244 Å, but extremely diffuse diffraction streaks normal to the hk 0 plane. In these streaks a period of 20.5 Å can be discerned. A hexagonal unit cell with a = 5.244(2) Å, c = 20.49(3) Å can be refined from the powder diffraction data but does not account for some lines, probably because of extreme layer disorder as shown by precession single-crystal patterns. The strong X-ray powder lines are (002, 10.22, 20); (-, 3.93, 20); (111, 2.608, 100); (300, 1.5145, 80); (220, 1.3111, 25). The formula given by microprobe analyses, constrained by density and molar volume data, is approximately (K,Ba) 2 (Ti,Mg,Ca,Fe) 4 (Si,Al,Fe) 6 O 14 (OH) 12 with K > Ba, Ti ≫ (Mg,Ca,Fe), Si > Al > Fe; Z = 1. These minerals are formed under oxidizing weathering conditions, and iron is assumed to be in the Fe 3+ state.

Arkansas↗