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USGS1979

United States Geological Survey Yearbook, fiscal year 1978

Fiscal year 1978 saw the U.S. Geological Survey continuing to perform its basic historical missions of collecting, analyzing, and disseminating information about the Earth, its processes, and its water and mineral resources. Classifying Federal lands and supervising lessee mineral extraction operations on those lands were also major Survey concerns during the year. In addition, substantial progress was made in the exploration and assessment of the petroleum potential of the National Petroleum Reserve in Alaska, a recently assigned mission. These basic missions found expression in a wide range of program activities and interests as diverse as the sands of Mars and the volcanoes of Hawaii. Programs included assessment of numerous potential energy and mineral resources, study of earthquakes and other geologic hazards, appraisal of the magnitude and quality of the Nation's water resources, and supervision of lease operations on Federal lands. The Survey also was involved in developing data on land use and producing topographic, geologic, and hydrologic maps for public and private use. In cooperation with other Federal agencies, the Survey participated in studies under the U.S. Climate Program and continued its analysis of data received from the two Viking landers on the surface of Mars. On April 3, 1978, Dr. H. William Menard became the 10th Director of the U.S. Geological Survey. Dr. Menard, who, until his appointment, was Professor of Geology at the Scripps Institution of Oceanography, San Diego, Calif., brings to the Director's post the experience gained in a long and successful career as a marine geologist and oceanographer. He succeeds Dr. Vincent E. McKelvey, who continues with the Survey as a senior research scientist.

Yearbook↗

USGS1998

Accounting for cyanide and its degradation products at three Nevada gold mines; constraints from stable C- and N-isotopes

An understanding of the fate of cyanide (CN-) in mine process waters is important for addressing environmental concerns and for taking steps to minimize reagent costs. The utility of stable isotope methods in identifying cyanide loss pathways has been investigated in case studies at three Nevada gold mines. Freshly prepared barren solutions at the mines have cyanide d15N and d13C values averaging -4 ? and -36 ?, respectively, reflecting the nitrogen and carbon sources used by commercial manufacturers, air and natural gas methane. Pregnant solutions returning from ore heaps display small isotopic shifts to lower d15N and d13C values. The shifts are similar to those observed in laboratory experiments where cyanide was progressively precipitated as a cyanometallic compound, and are opposite in sign and much smaller in magnitude than the shifts observed in experiments where HCN was offgassed. Offgassing is inferred to be a minor cyanide loss mechanism in the heap leach operations at the three mines, and precipitation as cyanometallic compounds, and possibly coprecipitation with ferric oxides, is inferred to be an important loss mechanism. Isotopic analysis of dissolved inorganic carbon (DIC) shows that uptake of high d13C air CO2 has been important in many barren and pregnant solutions. However, DIC in reclaim pond waters at all three mines has low d13C values of -28 to -34 ? indicating cyanide breakdown either by hydrolysis or by other chemical pathways that break the C-N bond. Isotope mass balance calculations indicate that about 40 % of the DIC load in the ponds, at a minimum, was derived from cyanide breakdown. This level of cyanide hydrolysis accounts for 14-100 % of the dissolved inorganic nitrogen species present in the ponds. Overall, isotope data provide quantitative evidence that only minor amounts of cyanide are lost via offgassing and that significant amounts are destroyed via hydrolysis and related pathways. The data also highlight the possibility that significant cyanide may be either retained in the ore heaps or destroyed via other chemical pathways.

Open-File Report↗

USGS2024

Quantifying fine sediment infiltration in spawning gravel used by Chinook salmon (Oncorhynchus tshawytscha) in the Sauk River Basin, Washington, 2018–21

Fine sediment can infiltrate into river substrate that salmonid fish species ( Oncorhynchus spp.) use to spawn. High levels of sediment infiltration can increase egg-to-fry mortality, which corresponds to the period when salmonids are still residing in the subsurface gravels. This study quantifies fine sediment infiltration of Chinook salmon ( Oncorhynchus tshawytscha ) spawning habitat during the egg-to-fry emergence period over three years in the Sauk River, which has naturally high fine sediment loads and important native salmon populations. Additionally, this study qualitatively assesses how grain size distribution of the riverbed and adjacent gravel bars compare to grain size distribution following fine sediment infiltration to evaluate if riverbed or gravel bar grain size distributions may provide information on the potential for fine sediment infiltration in spawning gravels. Fine sediment infiltration into spawning gravels was quantified using sediment boxes and infiltration bags that were installed in artificial redds constructed at known Chinook salmon spawning locations at three study sites on the Sauk River over the expected egg-to-fry period. Over the three-year study period (August 2018–April 2021), fraction finer of sediment (grain sizes of less than two millimeters), ranged from 0.12 to 0.23 across the three study sites and years. Based on a comparison of field observations from this study and percentage egg-to-fry survival curves found in the literature, the expected survival for Chinook salmon eggs in the Sauk River is roughly 30 percent. Expected survival increases to approximately 90 percent if eggs are eyed and thus farther along in their development. Our field study did not evaluate the progression of infiltration, so it is unknown if observed fine sediment infiltration was at this relatively high rate during the period that corresponded to early egg development, when eggs are more sensitive to fine sediment infiltration. Dissolved oxygen in the gravels is largely above critically low levels (4 milligrams per liter) during sensitive periods corresponding to egg development and is interpreted not to affect egg-to-fry mortality. Active channel morphology in the middle reaches of the Sauk River may pose an additional challenge to pre-emergence survival. Channel change, deposition, and potential scour at the middle Sauk River study site likely contributed to low recovery rates of both sediment boxes and infiltration bags in two of the three study years. In terms of grain size distributions of riverbed sediment and adjacent gravel bars representing the potential for fine sediment infiltration into spawning gravels, both riverbed and gravel bar bulk subsurface sediment samples had higher fraction finer for the representative fine grain size of two millimeters compared to the sediment boxes and infiltration bags. Therefore, riverbed and gravel bar samples may serve as a conservative first order proxy for potential fine sediment infiltration into spawning gravels, with the understanding that these samples may overestimate fine sediment infiltration by up to 15 percent.

Washington↗

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↗

USGS2007

A 3-Dimensional Model of Water-Bearing Sequences in the Dominguez Gap Region, Long Beach, California

A 3-dimensional computer model of the Quaternary sequence stratigraphy in the Dominguez gap region of Long Beach, California has been developed to provide a robust chronostratigraphic framework for hydrologic and tectonic studies. The model consists of 13 layers within a 16.5 by 16.1 km (10.25 by 10 mile) square area and extends downward to an altitude of -900 meters (-2952.76 feet). Ten sequences of late Pliocene to Holocene age are identified and correlated within the model. Primary data to build the model comes from five reference core holes, extensive high-resolution seismic data obtained in San Pedro Bay, and logs from several hundred water and oil wells drilled in the region. The model is best constrained in the vicinity of the Dominguez gap seawater intrusion barrier where a dense network of subsurface data exist. The resultant stratigraphic framework and geologic structure differs significantly from what has been proposed in earlier studies. An important new discovery from this approach is the recognition of ongoing tectonic deformation throughout nearly all of Quaternary time that has impacted the geometry and character of the sequences. Anticlinal folding along a NW-SE trend, probably associated with Quaternary reactivation of the Wilmington anticline, has uplifted and thinned deposits along the fold crest, which intersects the Dominguez gap seawater barrier near Pacific Coast Highway. A W-NW trending fault system that approximately parallels the fold crest has also been identified. This fault progressively displaces all but the youngest sequences down to the north and serves as the southern termination of the classic Silverado aquifer. Uplift and erosion of fining-upward paralic sequences along the crest of the young fold has removed or thinned many of the fine-grained beds that serve to protect the underlying Silverado aquifer from seawater contaminated shallow groundwater. As a result of this process, the potential exists for vertical migration of seawater into the producing aquifers and subsequent landward migration of intruded waters beneath the existing Dominguez barrier. Incipient invasion of the Silverado aquifer by chloride-enriched waters is observed in a recently drilled well located along the crest of the fold seaward of the barrier and at a depth of 440 feet (134 meters). These new observations and interpretations indicate that the new sequence-based approach to defining the stratigraphy of the Dominguez Gap area may have important implications for seawater intrusion management. To test this, it will be useful to overlay existing water-quality and water level data onto the framework model and to incorporate the new stratigraphy into a transport model.

Open-File Report↗

USGS2008

Geochemical trends and natural attenuation of RDX, nitrate, and perchlorate in the hazardous test area Fractured-Granite aquifer, White Sands Missile Range, New Mexico, 1996-2006

A fractured-granite aquifer at White Sands Missile Range is contaminated with the explosive compound RDX, nitrate, and perchlorate (oxidizer associated with rocket propellant) from the previous use of the Open Burn/Open Detonation site at the Hazardous Test Area. RDX, nitrate, and perchlorate ground-water concentrations were analyzed to examine source characteristics, spatial and temporal variability, and the influence of the natural attenuation processes of dilution and degradation in the Hazardous Test Area fractured-granite aquifer. Two transects of ground-water wells from the existing monitoring-site network - one perpendicular to ground-water flow (transect A-A') and another parallel to ground-water flow (transect B-B') - were selected to examine source characteristics and the spatial and temporal variability of the contaminant concentrations. Ground-water samples collected in 2005 from a larger sampling of monitoring sites than the two transects were analyzed for various tracers including major ions, trace elements, RDX degradates, dissolved gases, water isotopes, nitrate isotopes, and sulfate isotopes to examine the natural attenuation processes of dilution and degradation. Recharge entrains contaminants at the site and transports them downgradient towards the Tularosa Basin floor through a poorly connected fracture system(s). From 1996 to 2006, RDX, nitrate, and perchlorate concentrations in ground water downgradient from the Open Burn/Open Detonation site have been relatively stable. RDX, nitrate, and perchlorate in ground water from wells near the site indicate dispersed contaminant sources in and near the Open Burn/Open Detonation pits. The sources of RDX and nitrate in the pit area have shifted with time, and the shift correlates with the regrading of the south and east berms of each pit in 2002 and 2003 following closure of the site. The largest RDX concentrations were in ground water about 0.1 mile downgradient from the pits, the largest perchlorate concentrations were in ground water about 0.15 mile downgradient from the pits, and the largest nitrate concentrations were in ground water about 0.25 mile down-gradient from the pits. Strong and moderate correlation of water level and the contaminant concentrations near the source areas and low correlation outside and downgradient from the source areas indicates a diminishing of the water level/contaminant relation with downgradient flow. Ground water was not progressively older at all locations downgradient from the Open Burn/Open Detonation site indicating multiple recharge areas. Major ion and strontium concentrations and d2H and d18O values identified similar sources of recharge waters comprising the aquifer except along the basin periphery where recharge water may be influenced by dissolution of mineral assemblages associated with ore deposits that are present along the basin margins. Ground-water ages, dissolved-solids concentrations, and calcium-strontium concentrations indicate limited or partial connectivity between fractures and contributions of uncontaminated recharge water downgradient from the site that dilutes contaminant concentrations. Changes in RDX and nitrate concentration patterns, the presence of methane, changes in carbon dioxide concentrations and d15N and d34S values, and variable reduction-oxidation conditions suggest degradation of contaminants in the downgradient direction. Estimated values of electron potential were assigned to ground water collected in October 2005 from all monitoring sites at the Hazardous Test Area. Moderate to strong reducing conditions were present upgradient from the Open Burn/Open Detonation site, at the site, and at various locations downgradient from the site, but the aquifer contained well-oxygenated water between many of the reducing areas. The spatial variability of reduction-oxidation conditions in the aquifer exemplifies the partial connectivity of the fracture system(s). Dilution of the contaminants i

New Mexico↗

USGS1939

Geologic map and guide of the island of Oahu, Hawaii

This bulletin, although designated Bulletin 2, is actually the fourth of a series published by the Division of Hydrography of the Territory of Hawaii. All four of the bulletins thus far published relate to the geology and ground-water resources of the island of Oahu.1 Together they present the results obtained on this island in the program of ground-water investigation of the Territory that has been conducted in cooperation with the Geological Survey, of the United States Department of the Interior. Bulletin 5 which is in preparation will describe the progress made in developing the ground-water resources of Oahu since Bulletin 1 was issued. In Bulletin 2 is presented the detailed geologic map of Oahu that has resulted from this investigation. The base for this map is the new topographic map of Oahu prepared by the Topographic Branch of the Geological Survey. This bulletin also contains a guide to the geology along the main highways, which can be used advantageously in connection with the geologic map. For 18 years the writer has had the great privilege of working under the technical direction of Mr. 0. E. Meinzer, geologist in charge of the Division of Ground Water, U. S. Geological Survey. Nearly two decades ago Mr. Meinzer envisioned the great benefits that the people of Hawaii would derive from a thorough study of the groundwater resources of these islands. He also recognized that a full knowledge of these resources could be obtained only by a complete understanding of the geology of the islands and the processes which formed them. This bulletin is one of a series that has been made possible largely as a result of his broad vision. Credit is due Mr. W. 0 . Clark for the location of all the dikes shown on plate 2 in the headwaters of Kamananui Stream near the north end of the Koolau Range, and to Dr. C. K. Wentworth for about a dozen dikes north of Kaimuki. Messrs. 0. E. Meinzer, G. R. Mansfield, M. H. Carson, G. A. Macdonald, and S. H. Elbert kindly criticized the manuscript. Mr. Harry L. Taeuber designed the cover and with James Y. Nitta prepared the illustrations. Their work has greatly enriched this bulletin. The topographic maps of 15-minute quadrangles, on a scale of 1 to 20,000 (approximately 3 inches to the mile), were used in the field as a base for the geologic mapping. The data were then transferred to the new topographic map of Oahu, which is on a scale of 1 to 62,500. The resulting geologic map is reproduced as plate 2 (in pocket) of this report. Some of the outcrops are too small to be shown on this smaller map. Plate 2 of this report was listed as plate 2 in Bulletin 1, which was, however, published without the map because of the time required to prepare and engrave the topographic base and the geologic map. The geologic structure sections at the bottom of plate 2 were not described in Bulletin 1, but are discussed below.

Hawai'i↗

USGS2001

Soil efflux and total emission rates of magmatic CO2 at the horseshoe lake tree kill, mammoth mountain, California, 1995-1999

We report the results of eight soil CO2 efflux surveys by the closed circulation chamber method at the Horseshoe Lake tree kill (HLTK) - the largest tree kill on Mammoth Mountain. The surveys were undertaken from 1995 to 1999 to constrain total HLTK CO2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills. HLTK effluxes range from 1 to > 10,000 g m -2 day -1 (grams CO2 per square meter per day); they are not normally distributed. Station efflux rates can vary by 7-35% during the course of the 8- to 16-h surveys. Disturbance of the upper 2 cm of ground surface causes effluxes to almost double. Semivariograms of efflux spatial covariance fit exponential or spherical models; they lack nugget effects. Efflux contour maps and total CO2 emission rates based on exponential, spherical, and linear kriging models of survey data are nearly identical; similar results are also obtained with triangulation models, suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions. In addition, model estimates of total CO2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of CO2. Surveys since 1997 indicate that, contrary to earlier speculations, a termination of elevated CO2 emissions at the HLTK is unlikely anytime soon. The HLTK CO2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995-1999 surveys but maintained a N-S elongation, presumably reflecting fault control of CO2 transport from depth. Total CO2 emission rates also fluctuated greatly, ranging from 46 to 136 t day-1 (metric tons CO2 per day) and averaging 93 t day-1. The large inter-survey variations are caused primarily by external (meteorological) processes operating on time scales of hours to days. The externally caused variations can mask significant changes occurring at depth; a striking example is the masking of a degassing event generated at depth and detected by a soil gas sensor network in September 1997 while an efflux survey was in progress. Thus, occasional efflux surveys are not an altogether effective surveillance tool for the HLTK, and making them effective by greatly increasing their frequency may not be practical. Published by Elsevier Science B.V.

Chemical Geology↗

USGS1947

Electrochemical stabilization as a means of preventing ground failure in railroads

Laboratory and field data on electrochemical stabilization of clays, by three Russian authors, are here presented in translation. Abstracts of the Russian papers were published in May 1947 issue of the Engineering News Record (pp. 100-101). There exists also a small body of literature, in German and English, dealing with the electrochemical stabilization and related subjects. Elements of the electrochemical process were patented by Casagrande in Germany, shortly before the last war. Results of the Russians and of others, including the German patent, appear to be sound and interesting accordingly. Mechanism of the electrochemical stabilization, however, appears to be surmised rather than established. Unless the mechanism of such stabilization is understood in detail, little progress may be expected in field applications of the electrochemical method. Electroosmosis, a poorly reversible coagulation of the soil colloids, and introduction of exchangeable aluminum into the clay complex have been given credit for the ground-stabilizing effects of direct electrical current. Much remains to be done, as the reader may see, in developing further the theory of the method. A critical study is indicated, in this connection, by agencies or individuals qualified and equipped for basic research in soil physics. Optimum schedules for field treatments need be ascertained with particular care, to suit any given kind of material and environment. A wide range of variation in such schedules, is most certainly to be encountered in dealing with materials as diverse in their composition and properties as are clays. Any generalization on relationships between soil, electrolytes, moisture, and current could be premature if based on the Russian work alone. Stabilization of ground is a major engineering geologic problem of national interest. Needless to say, perhaps, that failures are to be expected, in laboratory and in the field, in this as well as in any other kind of research. To minimize probabilities of such failures, it may be recommended that investigators develop the electrochemical stabilization problem not merely against the relatively narrow background of soil mechanics, but with a certain feeling for geology, mineralogy, pedology, soil physics, and soil chemistry.

Open-File Report↗

USGS1980

Surface faulting near Livermore, California, associated with the January 1980 earthquakes

The earthquakes of 24 January (M s 5.8) 1980 north of Livermore, California, and 26 January (M s 5.2), were accompanied by surface faulting in the Greenville fault zone and apparently in the Las Positas fault zone also. The surface faulting was discontinuous and of small displacement. The main rupture within the Greenville fault zone trended about N.38°W. It was at least 4.2 km long and may have extended southward to Interstate Highway 580, giving a possible length of 6.2 km; both of these lengths included more gaps than observed surface rupture. Maximum displacements measured by us were about 25 mm of right slip (including afterslip through 28 January); vertical components of as much as 50 mm were seen locally, but these included gravity effects of unknown amount. The main break within the Greenville fault zones is very close to a fault strand mapped by Herd (1977, and unpublished data). A subsidiary break within the Greenville fault zone was about 0.5 km. long, had a general trend of N.46°W., and lay 0.12 to 0.25 km east of the main break. It was characterized by extension of as much as 40 mm and right slip of as much as 20 mm. This break was no more than 25 m from a fault mapped by Herd (unpublished data). Another break within the Greenville fault zone lay about 0.3 km southwest of the projection of the main break and trended about N33°W. It was at least 0.3 km long and showed mostly extension, but at several places a right-lateral component (up to 5 mm) was seen. This break was 80 to 100 m from a strand of the Greenville fault mapped by Herd (1977). Extensional fractures within the Greenville fault zone on the frontage roads north and south of Interstate Highway 580 may be related to regional extension or other processes, but do not seem to have resulted from faulting of the usual kind. One exception in this group is a fracture at the east side of Livermore valley which showed progressive increase in right-lateral displacement in February and March, 1980, and is directly on the projection of a fault in the Greenville fault zone mapped by Herd (1977). A group of more than 20 extensional fractures in Laughlin Road 1 km north of Interstate 580 probably are related to small tectonic displacements on faults in the Greenville fault zone. They are adjacent and parallel to two faults mapped by Herd (1977), are diagonal to the road, and most of them developed between 25 and 29 January, a period that included the M s 5.2 shock of 26 January. Observations at two locations indicate tectonic displacement on the Las Positas fault zone as mapped by Herd (1977). At Vasco Road a prominent break on a strand of the fault showed about 0.5 mm of left-lateral strike slip on 7 February. An alinement array across this and other fractures at the locality indicates about 6 mm of left-lateral displacement occurred between 21 February and 26 March. On Tesla Road several right-stepping fractures, one of which showed 1.5 mm of left-lateral strike slip, lie on or close tp previously mapped strands of the Las Positas fault zone. The evidence at these two localities indicates that tectonic surface displacement occurred along at least 1.1 km of the Las Positas fault zone.

California↗

USGS2023

Isotopic and geochemical evidence for the source of volcanism at Harrat Rahat, Kingdom of Saudi Arabia

Pleistocene and Holocene basalts, hawaiites, mugearites, benmoreites, and trachytes from the northern part of the Harrat Rahat volcanic field, Kingdom of Saudi Arabia, were analyzed for Sr, Nd, Hf, and Pb isotopic compositions. Evolved trachytes with Mg number <0.1 (Mg# = Mg/[Mg+Fe 2+ ], molar) have relatively radiogenic Sr isotopic compositions indicating that they were influenced by contamination probably in the upper crust. Volcanic rocks with Mg# >0.1, consisting chiefly of alkali basalts but encompassing hawaiites, mugearites, and benmoreites, show a limited range in Hf, Nd, Sr, and Pb isotopic compositions. Although the total Pb isotope variation is only 1 percent, the Pb isotope values correlate with Mg#, where the least radiogenic Pb is in samples with the lowest Mg#. The trend formed in Pb isotope space points toward an unradiogenic Pb composition that is similar to the Pb isotopic composition of lower crust of the Precambrian Arabian-Nubian Shields, as well as to feldspars and galena in the upper crust of the western Arabian Shield. This trend is interpreted as progressive but overall minor (no more than 5 weight percent) assimilation of shield rocks, or their partial melts, during fractional crystallization. Isotopic compositions of the least evolved northern Harrat Rahat magmas are most similar among analyzed Arabian harrats to depleted spreading-ridge basalts of the active Red Sea rift, but isotopic values are displaced toward those of spreading-ridge basalts of the Gulf of Aden that are proximal to the site of the Afar mantle plume. The Pb isotopic compositions very near the Northern Hemisphere Reference Line indicate no discernable lithospheric contribution to yield the parental basalts of northern Harrat Rahat, and their isotopic compositions are consistent with derivation predominantly from depleted Northern Hemisphere asthenosphere with a subordinate (20–30 weight percent) component from the Afar mantle plume. Trace-element variations show that appreciable portions of melting were in the garnet stability field, confirming the sub-lithospheric origin of the magmas, and that melting extents were low, accounting for the alkalic, trace-element-enriched character of the suite. The presence of possible Afar mantle beneath the western part of the Arabian Shield and its absence beneath the Red Sea rift may result from capture and channelized flow along high-relief structures incised into the base of the sub-continental lithosphere, as revealed by geophysical images.

northern Harrat Rahat↗

USGS2016

Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines

Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.

Scientific Reports↗

USGS1975

Hydrology of three sinkhole basins in southwestern Seminole County, Florida

The southwestern part of Seminole County--in east-central Florida-is characterized by sinkholes formed by the subsidence of surficial deposits into solution cavities in the underlying limestone deposits. The area includes three sinkhole basins created by such subsidence: Cranes Roost, Palm Springs, and Grace Lake. Cranes Roost basin (drainage area, 5.02 square miles) contains a closed drainage system of lakes and swamps--including Lakes Adelaide, Florida, and Mobile--that terminates at Cranes Roost sink. It also contains Lake Orienta and two unnamed sinks which do not overflow into Cranes Roost sink. Palm Springs basin (drainage area, 1.77 square miles) includes Lake Marion, Eleventh Hole Pond, and several small unconnected sinks. Grace Lake basin (drainage area, 1.64 square miles) includes Island Lake which overflows into Grace Lake. The recent spread of urban development has tended to encroach on the flood plains of lakes in these sinkhole basins and cause concern over the flood hazard that results. An investigation was made of the area to document the highest known lake levels, to examine possible effects of urbanization with regard to increasing the flood hazard, and to appraise the possibilities of controlling lake levels to reduce or limit the flood hazard. The highest lake stages of record in the three sinkhole basins occurred in September 1960. Analyses of the hydrologic relations between lake stages, ground-water levels, stream discharges, and rainfall in the area indicated that the lake stages of September 1960 probably were the highest attained since at least 1895. Cultural development that increases the percentage of a sink basin covered by impervious materials will cause more rapid runoff of a larger part of the rainfall in the basin. Thus, as development progresses, lake stages seldom reached under natural conditions may be reached more frequently unless the lake levels are controlled. In Crane Roost basin, the levels of Lakes Mobile, Adelaide, and Florida could be controlled by enlarging their surface outlets and adding control structures; however, such measures might be ineffective unless the level of Cranes Roost also was controlled. The level of Cranes Roost could be controlled by removal of water by pumping or by providing a surface outlet; pumping might be ineffective during extreme wet periods because of the potential for inflow from upstream lakes and the potential for ground-water inflow from the Floridan aquifer. The level of Lake Orienta could be Controlled by removal of water by pumping or by providing a surface outlet. In the Palm Springs sink basin, the levels of Lake Marion and the several small sinks could be controlled by removal of water by pumping or by providing surface outlets. For the several sinks, however, providing a surface outlet would require an extensive excavation and pumping might prove impractical because of seepage induced from the Floridan aquifer. The level of Island Lake--in Grace Lake sink basin-could be controlled by enlarging its surface outlet and providing a control structure. The peak stage of Grace Lake could be reduced by lowering its outlet to the north, but release of water during wet periods might cause downstream flooding.

Florida↗

USGS2018

Geologic map of the Fort Morgan 7.5' quadrangle, Morgan County, Colorado

The Fort Morgan 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. The South Platte River, originating high in the Colorado Rocky Mountains, has played a major role in shaping surficial geology in the map area, which is several tens of kilometers downstream from where headwater tributaries join the river. Recurrent glaciation (and deglaciation) of basin headwaters has affected river discharge and sediment supply far downstream, influencing deposition of alluvium and river incision in the Fort Morgan quadrangle. Distribution and characteristics of the alluvial deposits indicate that during the Pleistocene the course of the river within the map area shifted progressively southward as it incised, and by late middle Pleistocene the river was south of its present position, cutting and filling a deep paleochannel near the south edge of the quadrangle. The river shifted back to the north during the late Pleistocene. Kiowa and Bijou Creeks are unglaciated tributaries originating in the Colorado Piedmont east of the Front Range that also have played a major role in shaping surficial geology of the map area. Periodically during the late Pleistocene, major flood events on these tributaries deposited large volumes of sediment at and near their confluences, forming a broad, low-gradient fan composed of sidestream alluvium that could have occasionally dammed the river for short periods of time. Wildcat Creek, also originating on the Colorado Piedmont, and the small drainage of Cris Lee Draw dissect the map area north of the river. Eolian sand deposits of the Sterling (north of river) and Fort Morgan (south of river) dune fields cover much of the quadrangle and record past episodes of sand mobilization during times of prolonged drought. With the onset of irrigation and damming during historical times, the South Platte River has changed from a broad, shallow, and sandy braided river with highly variable seasonal discharge to a much narrower, deeper river with braided-meandering transition morphology and more uniform discharge.

Colorado↗

USGS1955

Water rights in areas of ground-water mining

Ground-water mining, the progressive depletion of storage in a ground-water reservoir, has been going on for several years in some areas, chiefly in the Southwestern States. In some of these States a water right is based on ownership of land overlying the ground-water reservoir and does not depend upon putting the water to use; in some States a right is based upon priority of appropriation and use and may be forfeited if the water is allowed to go unused for a specified period, but ownership of land is not essential; and in several States both these doctrines or modifications thereof are accepted, and each applies to certain classes of water or to certain conditions of development. Experience to date indicates that a cure for ground-water mining does not necessarily depend upon the water-rights doctrine that is accepted in the area. Indeed, some recent court decisions have incorporated both the areal factor of the landownership doctrines and the time factor of the appropriation doctrine. Overdraft can be eliminated if water is available from another source to replace some of the water taken from the affected aquifer. In areas where no alternate source of supply is available at reasonable cost, public opinion so far appears to favor treating ground water as a nonrenewable resource comparable to petroleum and metals, and mining it until the supply is exhausted, rather than curbing the withdrawals at an earlier date.

Circular↗

USGS2009

Acoustic Doppler current profiler applications used in rivers and estuaries by the U.S. Geological Survey

The U.S. Geological Survey (USGS) has collected streamflow information for the Nation's streams since 1889. Streamflow information is used to predict floods, manage and allocate water resources, design engineering structures, compute water-quality loads, and operate water-control structures. The current (2007) size of the USGS streamgaging network is over 7,400 streamgages nationwide. The USGS has progressively improved the streamgaging program by incorporating new technologies and techniques that streamline data collection while increasing the quality of the streamflow data that are collected. The single greatest change in streamflow measurement technology during the last 100 years has been the development and application of high frequency acoustic instruments for measuring streamflow. One such instrument, the acoustic Doppler current profiler (ADCP), is rapidly replacing traditional mechanical current meters for streamflow measurement (Muste and others, 2007). For more information on how an ADCP works see Simpson (2001) or visit http://hydroacoustics.usgs.gov/. The USGS has used ADCPs attached to manned or tethered boats since the mid-1990s to measure streamflow in a wide variety of conditions (fig. 1). Recent analyses have shown that ADCP streamflow measurements can be made with similar or greater accuracy, efficiency, and resolution than measurements made using conventional current-meter methods (Oberg and Mueller, 2007). ADCPs also have the ability to measure streamflow in streams where traditional current-meter measurements previously were very difficult or costly to obtain, such as streams affected by backwater or tides. In addition to streamflow measurements, the USGS also uses ADCPs for other hydrologic measurements and applications, such as computing continuous records of streamflow for tidally or backwater affected streams, measuring velocity fields with high spatial and temporal resolution, and estimating suspended-sediment concentrations. An overview of these applications is provided in the fact sheet.

Fact Sheet↗

USGS1982

High rates of bedload transport measured from infilling rate of large strudelscour craters in the Beaufort Sea, Alaska

Strudel scours are craters as much as 20 m wide and 4 m deep, that are excavated by vertical drainage flow during the yearly spring flooding of vast reaches of fast ice surrounding arctic deltas; they form at a rate of about 2.5 km^-2 yr^-1. Monitoring two such craters in the Beaufort Sea, we found that in relatively unprotected sites they fill in by deposition from bedload in 2 to 3 years. Net westward sediment transport results in sand layers dipping at the angle of repose westward into the strudel-scour crater, whereas the west wall of the crater remains steep to vertical. Initially the crater traps almost all bedload: sand, pebbles, and organic detritus; as infilling progresses, the materials are increasingly winnowed, and bypassing must occur. Over a 20-m-wide sector, an exposed strudel scour trapped 360 m3 of bedload during two seasons; this infilling represents a bedload transport rate of 9 m3 yr^-1 m^-1. This rate should be applicable to a 4.5-km-wide zone with equal exposure and similar or shallower depth. Within this zone, the transport rate is 40,500 m3 yr^-1, similar to estimated longshore transport rates on local barrier beaches. On the basis of the established rate of cut and fill, all the delta-front deposits should consist of strudel-scour fill. Vibracores typically show dipping interbedded sand and lenses of organic material draped over very steep erosional contacts, and an absence of horizontal continuity of strata--criteria that should uniquely identify high-latitude deltaic deposits. Given a 2- to 3-year lifespan, most strudel scours seen in surveys must be old. The same holds true for ice gouges and other depressions not adjusted to summer waves and currents, although these features record events of only the past few years. In view of such high rates of bottom reworking of the shallow shelf, any human activities creating turbidity, such as dredging, would have little effect on the environment. However, huge amounts of transitory material trapped by long causeways planned for offshore development would result in major changes in the environment.

Open-File Report↗

USGS1996

Configuration of freshwater/saline-water interface and geologic controls on distribution of freshwater in a regional aquifer system, central lower peninsula of Michigan

Electrical-resistivity logs and water-quality data were used to delineate the fresh water/saline-water interface in a 22,000-square-mile area of the central Michigan Basin, where Mississippian and younger geologic units form a regional system of aquifers and confining units. Pleistocene glacial deposits in the central Lower Peninsula of Michigan contain freshwater, except in a 1,600-square-mile area within the Saginaw Lowlands, where these deposits typically contain saline water. Pennsylvanian and Mississippian sandstones are freshwater bearing where they subcrop below permeable Pleistocene glacial deposits. Down regional dip from subcrop areas, salinity of ground water progressively increases in Early Pennsylvanian and Mississippian sandstones, and these units contain brine in the central part of the basin. Freshwater is present in Late Pennsylvanian sandstones in the northern and southern parts of the aquifer system. Typically, saline water is present in Pennsylvanian sandstones in the eastern and western parts of the aquifer system. Relief on the freshwater/saline-water interface is about 500 feet. Altitudes of the interface are low (300 to 400 feet above sea level) along a north-south-trending corridor through the approximate center of the area mapped. In isolated areas in the northern and western parts of the aquifer system, the altitude of the base of freshwater is less than 400 feet, but altitude is typically more than 400 feet. In the southern and northern parts of the aquifer system where Pennsylvanian rocks are thin or absent, altitudes of the base of freshwater range from 700 to 800 feet and from 500 to 700 feet above sea level, respectively. Geologic controls on distribution of freshwater in the regional aquifer system are (1) direct hydraulic connection of sandstone aquifers and freshwater-bearing, permeable glacial deposits, (2) impedance of upward discharge of saline water from sandstones by lodgement tills, (3) impedance of recharge of freshwater to bedrock (or discharge of saline water from bedrock) by Jurassic red beds, and (4) vertical barriers to ground-water flow within and between sandstone units.

Michigan↗