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At least 1,657 records · Page 92Linked to original sources
USGS2026

Guidelines for producing integrated 210Pb and 14C age-models

Accurate reconstructions of past environmental changes are crucial in paleoecological research and require reliable chronologies of sedimentary archives. Establishing robust age-models and obtaining the most appropriate proxies for analysis is a complex scientific endeavor, requiring extensive resources and collaboration among specialists, including radiochronologists. Radiometric dating methods, such as 210 Pb and radiocarbon ( 14 C), are frequently employed to establish chronologies in aquatic sedimentary deposits and peat bogs. In this study, we review key aspects of sampling, analysis, and the principles underlying 210 Pb and 14 C age-models, focusing on methods for developing robust joint chronologies for paleoenvironmental research. Drawing largely from the authors' experiences and group discussions during and after a scientific workshop in 2022, we discuss important considerations for site selection, sampling strategies, and radiometric dating to construct integrated 210 Pb and 14 C age-models. Using expert consensus, this group – called Paleostats – aims to provide a set of best practices for other geochronologists with this methods paper. Among our conclusions, we emphasize the importance of accounting for site-specific factors such as prior information on sedimentation rates to establish appropriate sampling and analytical strategies. The use of appropriate coring devices can minimize disturbance to sediments and ensure the core surface remains intact and preserved until sectioning. Where excess 210 Pb is expected, sectioning at intervals of ≤1 cm provides an adequate sampling resolution for 210 Pb dating. Exceptions are possible, allowing for ~2–3 cm sections in areas with confirmed high sedimentation rates (e.g., > 1 cm yr −1 ). Recovering deeper core sections for 14 C dating with sufficient overlap allows for accounting errors in depth estimates made in the field. Special attention is advised during time intervals where validation proxies, such as the human-made radionuclides 137 Cs or post-bomb 14 C, are expected, and to determine the depth of secular equilibrium between 210 Pb and 226 Ra. Radiocarbon analyses are commonly performed by accelerator mass spectrometry, and age models are constructed mainly using Bayesian statistics with Markov Chain Monte Carlo techniques (e.g., Bacon ). A Bayesian approach ( Plum ) is now available for producing 210 Pb age-models, which infers the 210 Pb ex flux, eliminates the need for selecting an equilibrium depth, and allows dating cores with incomplete 210 Pb ex inventory. Plum offers improved chronologies by integrating raw 210 Pb and 14 C data, and these age-models can be enriched with other dating methodologies, such as identifying tephras and other well-recorded historical events. Harmonized reporting would contribute to making radiometric age-models reproducible, which would benefit from an international effort. Using 210 Pb and 14 C to produce integrated age-models may yield better insights into the interplay between natural and recent anthropogenic forcings on ecosystems. This can enhance our understanding of environmental processes and their impacts on climate change, ultimately supporting science-based assessments and decisions.

Earth-Science Reviews↗
USGS2014

Database for the geologic map of upper Eocene to Holocene volcanic and related rocks in the Cascade Range, Washington

This geospatial database for a geologic map of the Cascades Range in Washington state is one of a series of maps that shows Cascade Range geology by fitting published and unpublished mapping into a province-wide scheme of lithostratigraphic units. Geologic maps of the Eocene to Holocene Cascade Range in California and Oregon complete the series, providing a comprehensive geologic map of the entire Cascade Range that incorporates modern field studies and that has a unified and internally consistent explanantion. The complete series will be useful for regional studies of volcanic hazards, volcanology, and tectonics. Originally a project supported by the Geothermal Research Program of the U.S. Geological Survey, the maps emphasize Quaternary volcanic rocks, because large igneous-related hydrothermal systems that have high temperatures are associated with Quaternary volcanic fields. Rocks older than a few million years are also included on the maps as they help to unravel geologic puzzles of the present-day Cascade Range. The deeply eroded older volcanoes found in the Western Cascades physiographic subprovince are analogues of today's snow-covered shield volcanoes and stratovolcanoes. The fossil hydrothermal systems of the Eocene to Pliocene vents now exposed provide clues to processes active today beneath the Pleistocene and Holocene volcanic peaks along the present-day crest of the Cascade Range. Study of these older rocks can aid in developing models of geothermal systems. These rocks also give insight into the origins of volcanic-hosted mineral deposits and even to future volcanic hazards. This digital database contains information used to produce the geologic map published as Sheet 1 in U.S. Geological Survey Miscellaneous Investigations Series Map I-2005. (Sheet 2 of Map I-2005 shows sources of geologic data used in the compilation and is available separately). Sheet 1 of Map I-2005 shows the distribution and relations of volcanic and related rock units in the Cascade Range of Washington at a scale of 1:500,000. This digital release is produced from stable materials originally compiled at 1:250,000 scale that were used to publish Sheet 1. The database therefore contains more detailed geologic information than is portrayed on Sheet 1. This is most noticeable in the database as expanded polygons of surficial units and the presence of additional strands of concealed faults. No stable compilation materials exist for Sheet 1 at 1:500,000 scale. The main component of this digital release is a spatial database prepared using geographic information systems (GIS) applications. This release also contains links to files to view or print the map sheet, main report text, and accompanying mapping reference sheet from Map I-2005. For more information on volcanoes in the Cascade Range in Washington, Oregon, or California, please refer to the U.S. Geological Survey Volcano Hazards Program website.

Washington↗
USGS1970

The Alaska earthquake, March 27, 1964: Lessons and conclusions

One of the greatest earthquakes of all time struck south-central Alaska on March 27, 1964. Strong motion lasted longer than for most recorded earthquakes, and more land surface was dislocated, vertically and horizontally, than by any known previous temblor. Never before were so many effects on earth processes and on the works of man available for study by scientists and engineers over so great an area. The seismic vibrations, which directly or indirectly caused most of the damage, were but surface manifestations of a great geologic event-the dislocation of a huge segment of the crust along a deeply buried fault whose nature and even exact location are still subjects for speculation. Not only was the land surface tilted by the great tectonic event beneath it, with resultant seismic sea waves that traversed the entire Pacific, but an enormous mass of land and sea floor moved several tens of feet horizontally toward the Gulf of Alaska. Downslope mass movements of rock, earth, and snow were initiated. Subaqueous slides along lake shores and seacoasts, near-horizontal movements of mobilized soil (“landspreading”), and giant translatory slides in sensitive clay did the most damage and provided the most new knowledge as to the origin, mechanics, and possible means of control or avoidance of such movements. The slopes of most of the deltas that slid in 1964, and that produced destructive local waves, are still as steep or steeper than they were before the earthquake and hence would be unstable or metastable in the event of another great earthquake. Rockslide avalanches provided new evidence that such masses may travel on cushions of compressed air, but a widely held theory that glaciers surge after an earthquake has not been substantiated. Innumerable ground fissures, many of them marked by copious emissions of water, caused much damage in towns and along transportation routes. Vibration also consolidated loose granular materials. In some coastal areas, local subsidence was superimposed on regional tectonic subsidence to heighten the flooding damage. Ground and surface waters were measurably affected by the earthquake, not only in Alaska but throughout the world. Expectably, local geologic conditions largely controlled the extent of structural damage, whether caused directly by seismic vibrations or by secondary effects such as those just described. Intensity was greatest in areas underlain by thick saturated unconsolidated deposits, least on indurated bedrock or permanently frozen ground, and intermediate on coarse well-drained gravel, on morainal deposits, or on moderately indurated sedimentary rocks. Local and even regional geology also controlled the distribution and extent of the earthquake's effects on hydrologic systems. In the conterminous United States, for example, seiches in wells and bodies of surface water were controlled by geologic structures of regional dimension. Devastating as the earthquake was, it had many long-term beneficial effects. Many of these were socioeconomic or engineering in nature; others were of scientific value. Much new and corroborative basic geologic and hydrologic information was accumulated in the course of the earthquake studies, and many new or improved investigative techniques were developed. Chief among these, perhaps, were the recognition that lakes can be used as giant tiltmeters, the refinement of methods for measuring land-level changes by observing displacements of barnacles and other sessile organisms, and the relating of hydrology to seismology by worldwide study of hydroseisms in surface-water bodies and in wells. The geologic and hydrologic lessons learned from studies of the Alaska earthquake also lead directly to better definition of the research needed to further our understanding of earthquakes and of how to avoid or lessen the effects of future ones. Research is needed on the origins and mechanisms of earthquakes, on crustal structure, and on the generation of tsunamis and local waves. Better earthquake-hazard maps, based on improved knowledge of regional geology, fault behavior, and earthquake mechanisms, are needed for the entire country. Their preparation will require the close collaboration of engineers, seismologists, and geologists. Geologic maps of all inhabited places in earthquake-prone parts of the country are also needed by city planners and others, because the direct relationship between local geology and potential earthquake damage is now well understood. Improved and enlarged nets of earthquake-sensing instruments, sited in relation to known geology, are needed, as are many more geodetic and hydrographic measurements. Every large earthquake, wherever located, should be regarded as a full-scale laboratory experiment whose study can give scientific and engineering information unobtainable from any other source. Plans must be made before the event to insure staffing, funding, and coordination of effort for the scientific and engineering study of future earthquakes. Advice of earth scientists and engineers should be used in the decision-making processes involved in reconstruction after any future disastrous earthquake, as was done after the Alaska earthquake. The volume closes with a selected bibliography and a comprehensive index to the entire series of U.S. Geological Survey Professional Papers 541-546. This is the last in a series of six reports that the U.S. Geological Survey published on the results of a comprehensive geologic study that began, as a reconnaissance survey, within 24 hours after the March 27, 1964, Magnitude 9.2 Great Alaska Earthquake and extended, as detailed investigations, through several field seasons. The 1964 Great Alaska earthquake was the largest earthquake in the U.S. since 1700. Professional Paper 546, in 1 part, describes Lessons and Conclusions.

Alaska↗
USGS2011

A reevaluation of the Pallett Creek earthquake chronology based on new AMS radiocarbon dates, San Andreas fault, California

The Pallett Creek paleoseismic record occupies a keystone position in most attempts to develop rupture histories for the southern San Andreas fault. Previous estimates of earthquake ages at Pallett Creek were determined by decay counting radiocarbon methods. That method requires large samples which can lead to unaccounted sources of uncertainty in radiocarbon ages because of the heterogeneous composition of organic layers. In contrast, accelerator mass spectrometry (AMS) radiocarbon dates may be obtained from small samples that have known carbon sources and also allow for a more complete sampling of the section. We present 65 new AMS radiocarbon dates that span nine ground‐rupturing earthquakes at Pallett Creek. Overall, the AMS dates are similar to and reveal no dramatic bias in the conventional dates. For many layers, however, individual charcoal samples were younger than the conventional dates, leading to earthquake ages that are overall slightly younger than previously reported. New earthquake ages are determined by Bayesian refinement of the layer ages based on stratigraphic ordering and sedimentological constraints. The new chronology is more regular than previously published records in large part due to new samples constraining the age of event R. The closed interval from event C to 1857 has a mean recurrence of 135 years ( σ = 83.2 years) and a quasiperiodic coefficient of variation (COV) of 0.61. We show that the new dates and resultant earthquake chronology have a stronger effect on COV than the specific membership of this long series and dating precision improvements from sedimentation rates.

California↗
USGS2004

Preliminary report on the 22 December 2003, M 6.5 San Simeon, California earthquake

The M w 6.5 San Simeon earthquake struck the central California coast on 22 December 2003 at 19:15:56 UTC (11:15:56 am local time.) The epicenter was located 11 km northeast of the town of San Simeon, and 39 km west-northwest of Paso Robles ( Figure 1 ), as reported by the California Integrated Seismic Network (CISN, the California region of the Advanced National Seismic System [ANSS]). The mainshock nucleated at 35.702°N, 121.108°W and a depth of 7.1 km, and the rupture propagated unilaterally to the southeast. The strong directivity of the rupture resulted in a concentration of damage and aftershock activity to the southeast of the hypocenter. The worst earthquake damage occurred in Paso Robles, where two people died in the collapse of an unreinforced masonry building. The accurate and rapid earthquake information provided in near real-time by CISN/ANSS to the Governor's Office of Emergency Services made it possible to focus emergency response in the source area, although the earthquake was felt from San Francisco to Los Angeles. The San Simeon earthquake occurred on a reverse fault striking northwest and most likely dipping to the northeast. Although motion along the Pacific-North America plate boundary in California is dominantly strike-slip, there is a small compressional component through central California. Repeated thrust earthquakes such as the San Simeon event accommodate this compression and build the Coast Ranges. Other recent thrust earthquakes in central California include the 1983 Coalinga (M 6.4) and the 1985 Kettleman Hills (M 6.0) earthquakes. Prior earthquakes in the vicinity of the San Simeon event include a M 5-6 earthquake in 1853, a M 5.7 earthquake in 1906, and the M L 6.2 Bryson earthquake of 1952 ( Figure 1 ) ( McLaren and Savage, 2001 .) The San Simeon earthquake occurred on a previously unknown blind thrust fault. No surface rupture associated with the earthquake has been identified. A number of roads, including State Highway 46, buckled due to the earthquake, but this deformation appears mainly to be failure of road fill due to ground shaking and not the result of tectonic surface rupture. Extrapolation of the fault plane to the surface would roughly align with the surface trace of the Oceanic Fault, but this is thought to be a vertical strike-slip fault. Two models for the kinematics of the region have previously been proposed. The first is a fault-propagation fold model developed by Namson and Davis ( 1990 ) for the Santa Lucia mountains ∼30 km to the southeast of the San Simeon sequence. The mainshock geometry is similar to, although more steeply dipping than, the main blind thrust of this model, implying that this model may be applicable to the San Simeon region as well. The second is the model of McLaren and Savage ( 2001 ), in which the region is dominated by strike-slip faulting with shortening on high-angle reverse faults. This model also may be applicable, although the dip of the San Simeon mainshock is shallower than predicted. The San Simeon earthquake was followed by a vigorous aftershock sequence, with 165 events above M 3 reported by CISN within the first week of the mainshock. Although the event triggered many aftershocks, it did not significantly impact the seismicity rates of other nearby faults such as the San Andreas Fault and the San Simeon-Hosgri fault zone. The only triggered seismicity seems to be a few small events within the mainshock coda at the Geysers geothermal area, north of San Francisco. The San Simeon earthquake did, however, trigger shallow creep on the San Andreas Fault at Parkfield and hydrologic changes in hot springs in Paso Robles.

California↗
USGS2015

Hydrologic record extension of water-level data in the Everglades Depth Estimation Network (EDEN), 1991-99

The real-time Everglades Depth Estimation Network (EDEN) has been established to support a variety of scientific and water management purposes. The expansiveness of the Everglades, limited number of gaging stations, and extreme sensitivity of the ecosystem to small changes in water depth have created a need for accurate water-level and water-depth maps. The EDEN water-surface elevation model uses data from approximately 240 gages in the Everglades to create daily continuous interpolations of the water-surface elevation and water depth for the freshwater portion of the Everglades from 2000 to the present (2014). These maps provide hydrologic data previously unavailable for assessing biological and ecological studies. Ecologists working in the Everglades expressed a need to the EDEN project team for daily EDEN water-level surfaces from 1990 to 1999. The additional 10 years of surfaces will provide ecologists and resource managers with two decades (1991–2011) of surfaces to analyze hydrologic dynamics. Before 2000, many of the EDEN gages used to generate water surfaces were not in operation. These datasets were extended to provide estimations of hydrologic time-series histories. The general approach to the record extension (hindcasts) was to (1) create a database of available data from 1990 to the present; (2) use dynamic cluster analysis to group stations with similar hydrologic behaviors for subareas of the Everglades with a large number of stations; (3) use results from the cluster analysis to select candidate explanatory variables; (4) develop linear regression or artificial neural network models to extend water-level records; and (5) evaluate record extensions by using model performance statistics and comparison of water-surface maps for similar hydrologic conditions for the hindcasted period (1991–99) and measured period (2000–11). To hindcast and fill data records, 214 empirical models were developed—189 are linear regression models and 25 are artificial neural network models. The coefficient of determination (R 2 ) for 163 of the models is greater than 0.80 and the median percent model error (root mean square error divided by the range of the measured data) is 5 percent. To evaluate the performance of the hindcast models as a group, contour maps of modeled water-level surfaces at 2-centimeter (cm) intervals were generated using the hindcasted data. The 2-cm contour maps were examined for selected days to verify that water surfaces from the EDEN model are consistent with the input data. The biweekly 2-cm contour maps did show a higher number of issues during days in 1990 as compared to days after 1990. May 1990 had the lowest water levels in the Everglades of the 21-year dataset used for the hindcasting study. To hindcast these record low conditions in 1990, many of the hindcast models would require large extrapolations beyond the range of the predictive quality of the models. For these reasons, it was decided to limit the hindcasted data to the period January 1, 1991, to December 31, 1999. Overall, the hindcasted and gap-filled data are assumed to provide reasonable estimates of station-specific water-level data for an extended historical period to inform research and natural resource management in the Everglades.

Florida↗
USGS1991

User's guide to the wetland creation/restoration data base, version 2

Wetland creation or restoration projects are frequently proposed as mitigation for unavoidable wetland losses, as components of wetland enhancement programs, and as tools to accomplish specific objectives such as waterfowl production or flood control. There is considerable controversy concerning the effectiveness of such projects as well as the most appropriate and efficient techniques to employ. The importance of the resource and the long time scales involved in fully evaluating a creation or restoration effort make it imperative to consider existing information as fully as possible in the development and evaluation of wetland creation or restoration proposals. To aid in the evaluation of wetland/creation efforts, the U.s. Fish and Wildlife Service (FWS), National Ecology Research Center, has developed the Wetland Creation/Restoration (WCR) Data Base. The data base is a highly indexed or keyworded bibliography of wetland creation or restoration articles. ("Articles" refers to any type of publication that deals specifically with wetland creation/restoration projects or studies.) The scope of the articles is international, although most of them are concerned with projects conducted in the United States. Information coded for each article includes author; citation; type of wetland and its location in terms of state, ecoregion, and FWS region; type of study undertaken; objectives in creating or restoring the wetland; actions performed to realize those objectives; length of time encompassed by the study; evaluation of results and responses to the wetland creation/restoration actions; and a listing of plant species significant to the project. A brief annotation summarizes the article and includes any significant additional information that may not be adequately reflected in the above described fields. Many of these articles describe only one or two components of a total wetland restoration effort. Planning a project that is designed to restore a wetland system (including at least some of its functions) is similar to constructing a picture from a number of puzzle pieces--missing pieces represent data gaps or information that is not available. Articles range from specific case studies, to overviews of restoration methods and techniques, to planning restoration projects and assessing programmatic and administrative backgrounds and interactions. In this data base, the term "restoration" is applied loosely to include rehabilitation of wetlands. It may refer to a number of situations or actions including, but not limited to: 1. breaching dikes or plugging drains; 2. water pollution clean-up; 3. conversion of eutrophic conditions; 4. wastewater treatment; 5. recolonization of previously disturbed or denuded areas; 6. amelioration of adverse conditions (erosion, wave, or wind action); 7. soil treatment --mulching, fertilization; 8. rerouting streams --may include construction of meander patterns; 9. monitoring natural vegetation; or 0. excluding grazers (geese, cattle) and monitoring results. This report describes the format and content of Version 2 of the WCR data base. Version 2 differs from the previous version described in SchnellerMcDonald et al. (1988): several fields have been dropped and condensed and new records have been added. Version 2 includes all records distributed with the earlier version and its updates. We recommend you replace any previous version with Version 2.

Book↗
USGS2024

Societal benefits of cyanobacteria harmful algal bloom management in Lake Okeechobee in Florida—Potential damages avoided during the 2018 event under U.S. Army Corps of Engineers Harmful Algal Bloom Interception, Treatment, and Transformation System scenarios

Freshwater harmful algal blooms (HABs) formed by blue-green algae, or cyanobacteria, have emerged as a global environmental problem. Their negative impacts on aquatic ecosystems can affect the benefits nature provides to human society by reducing water quality; inhibiting aquatic recreation; killing fish, wildlife, and pets; and posing a risk to human health. To manage harmful algal blooms, the Engineer Research and Development Center of the U.S. Army Corps of Engineers is developing an advanced technology called the Harmful Algal Bloom Interception, Treatment, and Transformation System (HABITATS), which has been tested in pilot demonstrations upstream of spillways at HAB-affected waterbodies in Florida. The U.S. Geological Survey and cooperators from the U.S. Department of the Interior Office of Policy Analysis investigated the societal benefits of HABITATS technology by using data from an actual 2018 harmful algal bloom in Lake Okeechobee to characterize the observed societal impacts and then comparing observed effects to hypothetical scenarios of HABITATS deployment. This study estimated an economic value of $5.5 million in foregone recreation as a result of closed boating ramp facilities and other restrictions on aquatic recreation such as fishing and swimming during the 2018 cyanobacteria harmful algal bloom outbreak. The change in housing sales prices that could have resulted from murky water or bad odor during that outbreak was estimated as $2.3 million. The team also investigated drinking water contamination and human illness but did not find significant societal impacts in this case. If HABITATS had been deployed, the avoided losses less the cost of management could have provided net societal benefits that ranged between negative $2.1 million and positive $0.8 million, depending on the vertical distribution of algae in the water column and the HABITATS version used. The study’s estimated societal benefit is undoubtedly a lower bound estimate because current scientific knowledge is inadequate to characterize, or monetize, all the impacts.

Florida↗
USGS2013

Salmonids, stream temperatures, and solar loading--modeling the shade provided to the Klamath River by vegetation and geomorphology

The U.S. Geological Survey is studying approaches to characterize the thermal regulation of water and the dynamics of cold water refugia. High temperatures have physiological impacts on anadromous fish species. Factors affecting the presence, variability, and quality of thermal refugia are known, such as riverine and watershed processes, hyporheic flows, deep pools and bathymetric factors, thermal stratification of reservoirs, and other broader climatic considerations. This research develops a conceptual model and methodological techniques to quantify the change in solar insolation load to the Klamath River caused by riparian and floodplain vegetation, the morphology of the river, and the orientation and topographic characteristics of its watersheds. Using multiple scales of input data from digital elevation models and airborne light detection and ranging (LiDAR) derivatives, different analysis methods yielded three different model results. These models are correlated with thermal infrared imagery for ground-truth information at the focal confluence with the Scott River. Results from nonparametric correlation tests, geostatistical cross-covariograms, and cross-correlograms indicate that statistical relationships between the insolation models and the thermal infrared imagery exist and are significant. Furthermore, the use of geostatistics provides insights to the spatial structure of the relationships that would not be apparent otherwise. To incorporate a more complete representation of the temperature dynamics in the river system, other variables including the factors mentioned above, and their influence on solar loading, are discussed. With similar datasets, these methods could be applied to any river in the United States—especially those listed as temperature impaired under Section 303(d) of the Clean Water Act—or international riverine systems. Considering the importance of thermal refugia for aquatic species, these methods can help investigate opportunities for riparian restoration, identify problematic reaches unlikely to provide good habitat, and simulate changes to solar loading estimates from alternative landscape configurations.

California↗
USGS1996

Methods for estimating low-flow characteristics of ungaged streams in selected areas, northern Florida

Methods for estimating low-flow frequency characteristics at ungaged sites were developed for two areas in northern Florida. In the Yellow, Blackwater, Escambia, and Perdido River Basins study area (northwestern Florida), regional regression equations were developed for estimating the 7- and 30-day, 2- and 10-year low-flow characteristic (Q7,2, Q7,10, Q30,2, and Q30,10) by determining values of basin characteristics from digital Geographical Information System (GIS) coverages or hardcopy maps. A GIS, ARC-INFO, was used to quantify basin characteristics that were used in regression equations. Sources of digital data used in this analysis are elevation data, from a digital elevation model, stream length and location data from a digital hydrography coverage, and watershed boundaries digitized from topographic maps. The most accurate regression equations employed a basin characteristic that was based on a simple conceptual model of one- dimensional ground-water flow using Darcy's law. Slightly less accurate equations were obtained using drainage area as the only explanatory variable. The standard error of prediction for the Darcy and drainage area equations of Q7,2 was 65 and 74 percent, respectively; Q7,10, 58 and 62 percent, respectively; Q30,2, 51 and, 54 percent, respectively; and Q30,10, 44 and 51 percent, respectively. In the Santa Fe River Basin study area (northeastern Florida), a flow-routing method was used to estimate low-flow characteristics at ungaged sites from low stream- flow analyses based on records at gaged sites. The use of the flow-routing method is suggested for areas where regression analysis proves unsuccessful, where low-flow characteristics have been defined at a significant number of sites, and where information about the basin characteristics has been thoroughly researched. Low-flow frequency characteristics determined at 40 sites and measurements made during five synoptic runs in 1989-91 were used to develop a flow-routing method. Low-flow frequency characteristics and drainage areas were used to define river profiles for major streams within the Santa Fe River Basin. These river profiles serve as indicators of changes in a stream's low-flow characteristics with respect to change in drainage area. Unit low flows were also determined for each site where low-flow characteristics were determined. Areas of zero flow were defined for Q7,2 and Q7,10 conditions based on measurements made during synoptic runs and from low-flow frequency analyses. The flow-routing method uses the drainage areas to interpolate low-flow values between or near gaged sites on the same stream. Low-flow values are transferred from a gaged site, either upstream or downstream, to the ungaged site. A step-by-step process for flow routing must be made when tributary or other inflow enter a stream. The strength of the flow-routing method is that the values at gaged sites reflect the overall basin characteristics in the vicinity of the gaged sites. However, the accuracy of low-flow estimates may be less in areas of decreasing and increasing flow if sufficient data are not available to assess changing hydraulic and hydrologic conditions.

Florida↗
USGS2015

Examination of the Reelfoot Rift Petroleum System, south-central United States, and the elements that remain for potential exploration and development

The Reelfoot rift is one segment of a late Proterozoic(?) to early Paleozoic intracontinental rift complex in the south-central United States. The rift complex is situated beneath Mesozoic to Cenozoic strata of the Mississippi embayment of southeastern Missouri, northeastern Arkansas, and western Tennessee and Kentucky. The rift portion of the stratigraphic section consists primarily of synrift Cambrian and Ordovician strata, capped by a postrift sag succession of Late Ordovician to Cenozoic age. Potential synrift source rocks have been identified in the Cambrian Elvins Shale. Thermal maturity of Paleozoic strata within the rift ranges from the oil window to the dry gas window. Petroleum generation in Elvins source rocks likely occurred during the middle to late Paleozoic. Upper Cretaceous sedimentary rocks unconformably overlie various Paleozoic units and define the likely upper boundary of the petroleum system. No production has been established in the Reel-foot rift. However, at least nine of 22 exploratory wells have reported petroleum shows, mainly gas shows with some asphalt or solid hydrocarbon residue. Regional seismic profiling shows the presence of two large inversion structures (Blytheville arch and Pascola arch). The Blytheville arch is marked by a core of structurally thickened Elvins Shale, whereas the Pascola arch reflects the structural uplift of a portion of the entire rift basin. Structural uplift and faulting within the Reelfoot rift since the late Paleozoic appear to have disrupted older conventional hydrocarbon traps and likely spilled any potential conventional petroleum accumulations. The remaining potential resources within the Reelfoot rift are likely shale gas accumulations within the Elvins Shale; however, reservoir continuity and porosity as well as pervasive faulting appear to be significant future challenges for explorers and drillers.

GCSSEPM Foundation Perkins-Rosen Research Conferen↗
USGS2023

What evidence exists on the ecological and physical effects of built structures in shallow, tropical coral reefs? A systematic map protocol

Background Shallow, tropical coral reefs face compounding threats from habitat degradation due to coastal development and pollution, impacts from storms and sea-level rise, and pulse disturbances like blast fishing, mining, dredging, and ship groundings that reduce coral reefs’ height and variability. One approach toward restoring coral reef structure from these threats is deploying built structures. Built structures range from engineered modules and repurposed materials to underwater sculptures and intentionally placed natural rocks. Restoration practitioners and coastal managers increasingly consider incorporating built structures, including nature-based solutions, into coral reef-related applications. Yet, synthesized evidence on the ecological and physical performance of built structure interventions across a variety of contexts (e.g., restoration, coastal protection, mitigation, tourism) is not readily available to guide decisions. To help inform management decisions, here we aim to document the global evidence base on the ecological and physical performance of built structures in shallow (≤ 30 m) tropical (35° N to 35° S latitude) coral ecosystems. The collated evidence base on use cases and associated ecological and physical outcomes of built structure interventions can help inform future consideration of built structures in reef restoration design, siting, and implementation. Method To discover evidence on the performance of built structures in coral reef-related applications, such as restoration, mitigation, and coastal protection, primary literature will be searched across indexing platforms, bibliographic databases, open discovery citation indexes, a web-based search engine, a novel literature discovery tool, and organizational websites. The geographic scope of the search is global, and there is no limitation to temporal scope. Primary literature will be screened first at the level of title and abstract and then at the full text level against defined eligibility criteria for the population, intervention, study type, and outcomes of interest. Metadata will be extracted from studies that pass both screening levels. The resulting data will be analyzed to determine the distribution and abundance of evidence. Results will be made publicly available and reported in a systematic map that includes a narrative description, identifies evidence clusters and gaps, and outlines future research directions on the use of built structures in coral reef-related applications.

Environmental Evidence↗
USGS2015

Applications of optical sensors for high-frequency water-quality monitoring and research

The recent commercial availability of in-situ optical sensors, together with new techniques for data collection and analysis, provides the opportunity to monitor a wide range of water-quality constituents over time scales during which environmental conditions actually change. Traditional approaches for data collection (daily to monthly discrete samples) are often limited by high sample collection, processing, and analytical costs, difficult site access, and logistical challenges, particularly for long-term sampling at a large number of sites. Optical sensors that continuously measure constituents in the environment by absorbance or fluorescence properties (Figure 1) have had a long history of use in oceanography for measuring highly resolved concentrations and fluxes of organic matter, nutrients, and algal material. However, much of the work using commercially-available optical sensors in rivers and streams has taken place in only the last few years. Figure 1. [NOT SHOWN] Optical sensor technology is now sufficiently developed to warrant broader application for research and monitoring in coastal and freshwater systems, and the United States Geological Survey (a U.S. science agency) is now using these sensors in a variety of research and monitoring programs to better understand water quality in-situ and in real-time. Examples are numerous and range from the applications of nitrate sensors for calculating loads to estuaries susceptible to hypoxia (Pellerin et al., 2014) to the use of fluorometers to estimate methymercury fluxes (Bergamaschi et al., 2011) and disinfection byproduct formation (Carpenter et al., 2013). Transmitting these data in real-time provides information that can be used for early trend detection, help identify monitoring gaps critical for water management, and provide science-based decision support across a range of issues related to water quality, freshwater ecosystems, and human health. Despite the value of these sensors, collecting data that meet high-quality standards requires investment in and adherence to tested and established methods and protocols for sensor operation and data management (Pellerin et al., 2013). For example, optical sensor measurements can be strongly influenced by a variety of matrix effects, including water temperature, inner filtering from highly colored water, and scattering of light by suspended particles (Downing et al., 2012). Characterizing and correcting sensors for these effects – as well as the continued development of common methodologies and protocols for sensor use – will be critical to ensuring comparable measurements across sites and over time. In addition, collaborative efforts such as the Nutrient Sensor Challenge (www.nutrients-challenge.org) will continue to accelerate the development, production and use of affordable, reliable and accurate sensors for a range of environments. REFERENCES Bergamaschi .B.A., Fleck J.A., Downing B.D., Boss E., Pellerin B.A., Ganju N.K., Schoellhamer D.H., Byington A.A., Heim W.A., Stephenson M., Fujii R. (2011), Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements. Limnology and Oceanography, 56(4): 1355-1371. Carpenter K.D., Kraus T.E.C., Goldman J.H., Saraceno J., Downing B.D., Bergamaschi B.A., McGhee G., Triplett T. (2013), Sources and Characteristics of Organic Matter in the Clackamas River, Oregon, Related to the Formation of Disinfection By-products in Treated Drinking Water: U.S. Geological Survey Scientific Investigations Report 2013–5001, 78 p. Downing .B.D., Pellerin B.A., Bergamaschi B.A., Saraceno J., Kraus T.E.K. (2012), Seeing the light: The effects of particles, temperature and inner filtering on in situ CDOM fluorescence in rivers and streams. Limnology and Oceanography: Methods, 10: 767-775. Pellerin B.A., Bergamaschi B.A., Downing B.D., Saraceno J., Garrett J.D., Olsen L.D. (2013), Optical Techniques for the Determination of Nitrate in En

Conference Paper↗
USGS2003

Worldwide asbestos supply and consumption trends from 1900 to 2000

The use of asbestos is one of the most controversial issues surrounding the industrial minerals industry. Its carcinogenic nature, an overall lack of knowledge of minimum safe exposure levels, its widespread use for more than 100 years, and the long latency for the development of lung cancer and mesothelioma are the main contributing factors to these controversies. Another factor is that, despite decades of research, the mechanisms responsible for its carcinogenic properties are still largely unknown. The United States has produced about 3.28 million metric tons of asbestos fiber and used approximately 31.5 million tons between 1900 and 2000. About half of this amount was used since 1960. Cumulative world production during that same time period was about 173 million tons. Assuming that unusually large stocks are not maintained and that world consumption roughly equals production, about half of the world production and consumption occurred since 1976. The United States and western European nations were the largest consumers of asbestos during the first two-thirds of the 20th century. They were surpassed by the collective production and consumption of States within the former Soviet Union by the 1970s. With the onset of the health issues concerning asbestos in the late 1960s and early 1970s, world production and consumption began to decline during the 1980s. In 2000, world consumption, estimated to be 1.48 million tons, was only 31% that of 1980. Countries in Asia, South America, and the former Soviet Union remain the largest users of asbestos. More specifically, Brazil, China, India, Japan, Russia, and Thailand are the only countries that consumed more than 60,000 tons of asbestos in 2000. These six countries accounted for more than 80% of world?s apparent consumption in 2000.

Open-File Report↗
USGS2021

A characterization of deep-sea coral and sponge communities along the California and Oregon coast using a remotely operated vehicle on the EXPRESS 2018 expedition

Deep-sea coral and sponge (DSCS) communities serve as essential fish habitats (EFH) by providing shelter and nursery habitat, increasing diversity, and increasing prey availability (Freese and Wing, 2003; Bright, 2007; Baillon et al., 2012; Henderson et al., 2020). Threats to these long-lived, fragile organisms from bottom contact fishing gear, potential offshore renewable energy development, and ocean warming and acidification have increased the need for DSCS research along the U.S. West Coast (Gomez et al., 2018; Salgado et al., 2018; Yoklavich, et al., 2018; Gugliotti et al., 2019). The focus of these studies has varied from species distribution and abundance (Yoklavich and Love, 2005; Tissot et al., 2006) to developing and validating predictive distribution models (Huff et al., 2013; Rooper et al., 2017; Kreidler, 2020) to finding medicinal uses for corals and sponges (Essack et al., 2011; Shrestha et al., 2018). Due to the vast area of unexplored seafloor within the U.S. exclusive economic zone (EEZ; 200 nautical miles off the coast) and the technological requirements and expanse of deep-sea research, there is still much to learn about the distributions and biology of DSCS. This information is critical to resource managers for effective conservation and management of DSCS habitats. Protections are provided by the Pacific Fishery Management Council (PFMC) designation of groundfish EFH conservation areas (EFHCA) and the National Marine Sanctuaries Act (NMSA). Areas designated as EFHCA are closed to bottom trawl fishing to protect and preserve seafloor habitats. Recently the PFMC adopted Amendment 28 to the Groundfish Fishery Management Plan (GFMP; Pacific Fishery Management Council, 2019) which modified EFHCAs by closing new areas identified as vulnerable and reopening areas deemed not vulnerable. The NMSA prohibits bottom disturbance from certain activities within areas designated as national marine sanctuaries, such as oil and gas exploration or extraction, cable laying, and other forms of seabed alteration or construction that disturb benthic communities. NOAA’s Deep-Sea Coral and Research Technology Program (DSCRTP) began a 4-yr funding initiative for the U.S. West Coast in 2017. The goals of the West Coast Deep-Sea Coral Initiative (WCDSCI) were to: 1) gather baseline information on areas subject to fishing regulation changes prior to the implementation of Amendment 28; 2) improve our understanding of known DSCS bycatch “hot spots”; and 3) explore and assess DSCS resources within NOAA National Marine Sanctuaries with emphasis on areas of sanctuary resource protection and management concerns. During the first year of the program, a research cruise was developed to survey the West Coast from Oregon to California studying the DSCS ecosystems in priority areas. The 31-day expedition (9 Oct – 8 Nov, 2018) was launched from the NOAA Ship Bell M. Shimada, beginning in Newport, OR and ending in San Diego, CA. The science team assembled for this cruise were members of the EXpanding Pacific Research and Exploration of Submerged Systems (EXPRESS) campaign, which brings together researchers from federal and nonfederal institutions to collaborate on scientific expeditions targeting the deepwater areas off California, Oregon, and Washington. EXPRESS supports researchers leveraging funding, resources, personnel, and expertise to accomplish more science than would have been possible by a single entity alone. The 2018 coastwide expedition included research partners from National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) and Northwest Fisheries Science Center (NWFSC), National Ocean Service (Channel Islands, Cordell Bank, Greater Farallones, and Monterey Bay National Marine Sanctuaries), Bureau of Ocean Energy Management (BOEM), U.S. Geological Survey (USGS), and Monterey Bay Aquarium Research Institute (MBARI). Research objectives for the cruise were to: 1) Collect DSCS baseline information at 10 of the EFHCA sites undergoing protection modifications by the Pacific Fishery Management Council. 2) Collect DSCS and fish data at previously unexplored sites within West Coast National Marine Sanctuaries. 3) Revisit a subset of previously surveyed sites to document if changes in DCSC have occurred over time. 4) Collect information to validate BOEM supported cross-shelf habitat suitability models for DSCS. 5) Collect samples to help in identifying (and understanding) West Coast DSCS and expand use of new technologies (ROV, AUV, and environmental DNA [eDNA]). 6) Collect water samples for coastwide eDNA, nutrient, and carbon chemistry studies.

California, Oregon↗
USGS1994

Water-resources activities of the U.S. Geological Survey in New Mexico, fiscal year 1992

Awareness of our environment in general, and water resources in particular, has brought increased interest in and support of hydrologic data collection and research. The quantity, quality, and distribution of water are extremely important to the future well-being of New Mexico. The State's surface-water resources are minimal and highly variable due to climate and to regulation and diversion; ground-water resources are subject to development that exceeds natural recharge and to potential contamination by land use. Issues related to global climate change, disposal of hazardous wastes, toxic substances in water, water rights, and ground-water contamination are evolving areas of greater public concern. At the same time there is a continuing need for a better understanding of various hydrologic systems and processes in order to manage these limited water resources for maximum benefit to present and future generations. The U.S. Geological Survey has collected and disseminated information on the water resources of New Mexico for more than a century. The Survey began to collect records of streamflow in New Mexico in December 1888 when the first discharge measurements were made on the Rio Grande near the present gaging station at Embudo. This site, called the "birthplace of systematic stream gaging," was chosen to be the training center for the first hydrographers of the Irrigation Survey, a bureau within the original Geological Survey. Since that time, in cooperation with Federal, State, local, and tribal agencies, we have monitored streams at hundreds of sites throughout the State and have a current network of more than 200 streamflow-gaging stations. Through the Cooperative Program, we also have established sites where ground-water levels are monitored to document changes in ground-water storage or where surface-water and groundwater samples are collected to determine water chemistry, and we have undertaken investigative studies to define the availability, quality, and distribution of water resources. Information from the data program and results of investigative studies are made available to water-resources managers, regulators, and the public to be used for the effective management of the State's water resources. This report provides a brief summary of the activities of the New Mexico District for FY (fiscal year) 1992, including our mission, organization, sources of funding, and descriptions of current projects. This report serves to document not only the content of the program, but also the diversity and complexity of that program. Cooperation among water-resources agencies will be essential in effectively dealing with water-related issues facing New Mexico. We look forward to the challenge of addressing these issues by continuing to provide factual hydrologic data and technically sound areal appraisals and interpretive studies.

New Mexico↗
USGS2011

Genetic identity of Thamnophis sp. using microsatellite genetic markers

Butler’s gartersnake (Thamnophis butleri) was previously listed by the Wisconsin Department of Natural Resources as a state threatened species. Several key questions associated with species identity, integrity, and hybridization with other gartersnake species needed to be addressed to further refi ne the management plan for this species. The objectives of this research were: 1) to determine if genetic markers developed in the initial phase of research could identify discrete genetic groups of Wisconsin gartersnakes, 2) to determine if any or all genetic groups delineated in objective one were consistent with Butler’s gartersnake, plains gartersnake (T. radix), and/or common gartersnake (T. sirtalis), and 3) to determine if any of the genetic data were consistent with hybridization occurring between gartersnakes in Wisconsin. Snakes were sampled from various Midwestern locations with a focus on sites in Wisconsin. All snakes were photo-vouchered, morphological landmarks were taken, and a tail snip was collected for genetic analysis. Genetic data from previously developed microsatellite markers discriminated three genetic groups from a composite 13-locus dataset (N=815) using the Bayesian admixture analysis in STRUCTURE v2.3.3. These units were highly consistent with species-groups based on the membership of a small number of known snakes from areas where the species are not thought to co-occur. Using a threshold q-value (proportional genotype) of ≥80%, 498 Butler’s gartersnakes, 93 plains gartersnakes, and 107 common gartersnakes were identifi ed in Wisconsin samples; putative hybrid snakes of Butler’s gartersnake x plain gartersnake (34), Butler’s gartersnake x common gartersnake (8), and a single ambiguous snake were also identifi ed in Wisconsin samples. Levels of divergence among the species groups from Wisconsin were lower than between species groups from other states consistent with either larger than expected Wisconsin population sizes or signifi cant gene fl ow (introgressive hybridization) having occurred among species. Regardless, levels of divergence and overall integrity of the three groups were such that the presence of three species of gartersnakes in Wisconsin was supported and hybridization, at a minimum between Butler’s gartersnakes and the two other species, was shown to occur.

Wisconsin DNR Research Report↗
USGS2000

Puerto Rico: Marine sediments, terrestrial and seafloor imagery, and tectonic interpretations

Introduction: Puerto Rico is an island situated in the plate boundary zone between the Caribbean and the North American Plates. This is a geologically fascinating, tectonically active region, where the Caribbean Plate has over-ridden the North American Plate and is now sliding past it with strike-slip motion. The details of this tectonic interaction are poorly understood, largely because much of the region lies under water, making it difficult to study. The geologic setting of Puerto Rico has created or contributed to several pressing societal issues, related to human safety, environmental health, and economic development. Because the island lies on an active plate boundary, earthquakes are a constant threat and the densely populated coastal areas are vulnerable to tsunamis. Coastal erosion is a concern in many coastal areas, but is particularly serious to an island economy which relies heavily on a thriving tourist industry. In Puerto Rico, illegal mining of beach sands for use as aggregate has exacerbated coastal erosion and left coastal communities more exposed to the ravages of storms and tsunamis. The serious need for an affordable local source of aggregate to use in the growing construction industry on the island has created a strong interest in locating and evaluating offshore sand and gravel deposits. During the last 20 years the U.S. Geological Survey, often in cooperation with the Puerto Rico Department of Natural Resources and/or the University of Puerto Rico, has conducted a variety of projects to address the geologic aspects of these pressing societal issues. The papers and data presented here are the results of these projects. Some have been previously published elsewhere; others, such as the database of surficial sediments of the Puerto Rico insular shelf, interpretation of side-looking airborne radar imagery of the island, and the GIS data, are presented here for the first time. The purpose of this CD is to make the results of these diverse studies available in a readily accessible digital form, so that managers, planners, and other researchers can utilize the results.

Puerto Rico↗