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Results for “Coastal Sediments”

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

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At least 253 records · Page 14Linked to original sources
USGS2010

Chlorofluorocarbons (CCl3F and CCl2F2) as dating tools and hydrologic tracers in shallow groundwater of the Delmarva Peninsula, Atlantic Coastal Plain, United States

Concentrations of the Chlorofluorocarbons (CFCs) CFC-11 and CFC-12 were determined in groundwater from coastal plain sediments of the Delmarva Peninsula. CFC-modeled ages were calculated independently for CFC-11 and CFC-12, and agreed to within 2–3 years in the majority of the waters. Recharge temperatures, determined from dissolved nitrogen and argon concentrations, varied from 9±2°C over most of the peninsula to 14±2°C at the southernmost tip of the peninsula in Virginia. The CFC-modeled ages were examined in relation to the known hydrogeologic environment, both on regional scales and in more intensively sampled local scale networks. The CFC-modeled recharge years and measured tritium concentrations were used to reconstruct a tritium input function that was compared to the modeled tritium plus 3 He distribution. Most of the present distribution of tritium in Delmarva groundwater is consistent with low dispersivities. The results of the study strongly support the use of CFCs for dating shallow, aerobic groundwater.

Delaware, Maryland↗
USGS2010

Dating of shallow groundwater: Comparison of the transient tracers 3H/3He, chlorofluorocarbons, and 85Kr

This paper describes a direct comparison of apparent ages derived from 3 H/ 3 He, chlorofluorocarbons (CCl 3 F and CCl 2 F 2 ), and 85 Kr measurements in shallow groundwater. Wells chosen for this study are completed in the unconfined surficial aquifers in late Cenozoic Atlantic Coastal Plain sediments of the Delmarva Peninsula, on the east coast of the United States. Most of the apparent tracer ages agree within 2 years of each other for recharge dates between 1965 and 1990. Discrepancies in apparent tracer ages usually can be explained by hydrological processes such as mixing in a discharge area. Recharge rate calculations based on apparent tracer age gradients at multilevel well locations agree with previous recharge estimates. High recharge rates on the Delmarva Peninsula result in nearly complete dissolved-gas confinement in the groundwater. The remarkable agreement between the different tracer ages indicates negligible mixing of waters of different ages, insignificant dispersion, minimal gas loss to the atmosphere, and insignificant sorption-desorption processes at this location.

Water Resources Research↗
USGS2020

Historically unprecedented Northern Gulf of Mexico hurricane activity from 650 to 1250 CE

Hurricane Michael (2018) was the first Category 5 storm on record to make landfall on the Florida panhandle since at least 1851 CE (Common Era), and it resulted in the loss of 59 lives and $25 billion in damages across the southeastern U.S. This event placed a spotlight on recent intense (exceeding Category 4 or 5 on the Saffir-Simpson Hurricane Wind Scale) hurricane landfalls, prompting questions about the natural range in variability of hurricane activity that the instrumental record is too short to address. Of particular interest is determining whether the frequency of recent intense hurricane landfalls in the northern Gulf of Mexico (GOM) is within or outside the natural range of intense hurricane activity prior to 1851 CE. In this study, we identify intense hurricane landfalls in northwest Florida during the past 2000 years based on coarse anomaly event detection from two coastal lacustrine sediment archives. We identified a historically unprecedented period of heightened storm activity common to four Florida panhandle localities from 650 to 1250 CE and a shift to a relatively quiescent storm climate in the GOM spanning the past six centuries. Our study provides long-term context for events like Hurricane Michael and suggests that the observational period 1851 CE to present may underrepresent the natural range in landfalling hurricane activity.

Gulf of Mexico↗
USGS1969

Longitudinal slope characteristics of rivers of the midcontinent and the Atlantic east gulf slopes

This study of longitudinal stream profiles of rivers of the Midcontinent (rivers tributary to the Mississippi) and Atlantic and East Gulf Slopes has revealed five types of longitudinal profiles: (1) Overall concave-upward profiles with or without long constant slope segments; (2) convex upward, for example, the Missouri River has a profile that has a constant slope for its lower 560 miles and then is convex upward with constant slope segments to a point beyond the Yellowstone River junction; (3) concave-upward irregular, ungraded, low-gradient profiles (Ohio and Tennessee Rivers); (4) irregular unsegmented and steep profiles, such as shown by the Delaware and Savannah-Tugaloo Rivers; and (5) irregular ungraded, steep-gradient profiles that are concave-upward in the upstream reaches and downstream convex-upward, for example, on most of the Atlantic Slope and East Gulf Slope Rivers above the Fall Line. Constant slope profiles occur where the last type of rivers flow across relatively weak Coastal Plain sediments and also inland on the Coosa and Oostanaula-Conasauga Rivers. The profile characteristics of the Atlantic and East Gulf streams lend support to the hypothesis of multiple erosion cycles in the Appalachians. © 1969 Taylor & Francis Group, LLC.

International Association of Scientific Hydrology ↗
USGS2019

Comparison of a simple hydrostatic and a data-intensive 3D numerical modeling method of simulating sea-level rise induced groundwater inundation for Honolulu, Hawai'i, USA

Groundwater inundation (GWI) is a particularly challenging consequence of sea-level rise (SLR), as it progressively inundates infrastructure located above and below the ground surface. Paths of flooding by GWI differ from other types of SLR flooding (i.e., wave overwash, storm-drain backflow) such that it is more difficult to mitigate, and thus requires a separate set of highly innovative adaptation strategies to manage. To spur consideration of GWI in planning, data-intensive numerical modeling methods have been developed that produce locally specific visualizations of GWI, though the accessibility of such methods is limited by extensive data requirements. Conversely, the hydrostatic (or 'bathtub') modeling approach is widely used in adaptation planning owing to easily accessed visualizations (i.e., NOAA SLR Viewer), yet its capacity to simulate GWI has never been tested. Given the separate actions necessary to mitigate GWI relative to marine overwash, this is a significant gap. Here we compare a simple hydrostatic modeling method with a more deterministic, dynamic and robust 3D numerical modeling approach to explore the effectiveness of the hydrostatic method in simulating equilibrium aquifer effects of multi-decadal sea-level rise, and in turn GWI for Honolulu, Hawai'i. We find hydrostatic modeling in the Honolulu area and likely other settings may yield similar results to numerical modeling when referencing the local mean higher-high water tide datum (generally typical of flood studies). These findings have the potential to spur preliminary understanding of GWI impacts in municipalities that lack the required data to conduct rigorous groundwater-modeling investigations. We note that the methods explored here for Honolulu do not simulate dynamic coastal processes (i.e., coastal erosion, sediment accretion or changes in land cover) and thus are most appropriately applied to regions that host heavily armored shorelines behind which GWI can develop.

Hawaii↗
USGS1974

Buried Triassic basin in the central Savannah River area, South Carolina and Georgia

A basin filled with Triassic red beds, located on the South Carolina–Georgia line ∼32 km southeast of Augusta, Georgia, is buried beneath ∼350 m of Coastal Plain sediments. An extensive aeromagnetic survey, seismic refraction and reflection surveys, and geophysical logs and samples from three wells define the extent and character of the basin. This basin, herein named the Dunbarton Triassic basin, is ∼50 km long, 10 km wide, and trends northeast. The northwest margin of the basin is well defined by the aeromagnetic survey, a seismic reflection traverse, and a well that passed through 485 m of Triassic fanglomerate before entering the crystalline metamorphic rocks below. Near the center of the Triassic basin, a well passed through 902 m of maroon Triassic mudstone and sandstone of fluvial origin without penetrating the bottom of the basin. The permeability of the Triassic rock is extremely low, and water-transmitting fractures were not penetrated. Even slight water-level disturbances in the Triassic wells require many years to recover. Total dissolved solids of the water from the Triassic basin are about twice that in the crystalline metamorphic rocks that surround it. The inferred geologic history of this basin is similar to the history of Triassic basins that crop out in North Carolina.

Georgia, South Carolilna↗
USGS2019

A federal-state partnership for mapping Florida's coast and seafloor

The Florida Coastal Mapping Program, a partnership of state and federal agencies, has a goal of having modern, consistent, high- resolution sea-floor data for all of Florida’s coastal zone in the next decade to support a myriad of coastal zone science and management applications. One of the early steps in the implementation process is to prioritize and justify mapping needs. This is accomplished by holding six regional workshops across the state during which stakeholders and partners are introduced to a newly developed geospatial prioritization tool. Users independently utilize the tool to populate grid cells for a given region, and the result is a cumulative perspective on sea floor mapping priorities to inform future mapping initiatives. The tool also allows participants to indicate their primary use of sea floor mapping data and types of additional data required for their science or management need.

Florida↗
USGS1997

Delineating paleochannels using shallow seismic reflection

Discontinuous confining units beneath industrialized areas provide effective pathways for contaminants to move from one aquifer to another within Atlantic Coastal Plain sediments. Shallow seismic reflection can provide coherent high resolution images of thin, alternating sand and clay sequences in many shallow water table environments — useful, cost‐effective information which can significantly enhance environmental investigations.

Leading Edge (Tulsa, OK)↗
USGS2015

The 21 May 2014 M w 5.9 Bay of Bengal earthquake: macroseismic data suggest a high‐stress‐drop event

A modest but noteworthy M w 5.9 earthquake occurred in the Bay of Bengal beneath the central Bengal fan at 21:51 Indian Standard Time (16:21 UTC) on 21 May 2014. Centered over 300 km from the eastern coastline of India (Fig. 1), it caused modest damage by virtue of its location and magnitude. However, shaking was very widely felt in parts of eastern India where earthquakes are uncommon. Media outlets reported as many as four fatalities. Although most deaths were blamed on heart attacks, the death of one woman was attributed by different sources to either a roof collapse or a stampede (see Table S1, available in the electronic supplement to this article). Across the state of Odisha, as many as 250 people were injured (see Table S1), most after jumping from balconies or terraces. Light damage was reported from a number of towns on coastal deltaic sediments, including collapsed walls and damage to pukka and thatched dwellings. Shaking was felt well inland into east‐central India and was perceptible in multistoried buildings as far as Chennai, Delhi, and Jaipur at distances of ≈1600  km (Table 1).

Seismological Research Letters↗
USGS1984

Geophysical methods as mapping tools in a strata-bound gold deposit: Haile mine, South Carolina slate belt

Very low frequency electromagnetic, magnetic, and induced polarization methods. The very low frequency electromagnetic resistivity data show high resistivity zones that correlate with siliceous units known to host the gold. The magnetic data clearly identify the mafic and ultramafic dikes which cut metasediments and also fill faults that offset them. The induced polarization method allows examination of the mineralized metasediments in two dimensions by giving vertical sections of resistivity and percent frequency effect, parameters which correlate with silica and pyrite content, respectively. Lithologic units as well as ore zones can thus be mapped in this terrain which is deeply weathered and partially covered by coastal plain sediments.

Economic Geology↗
USGS1953

Stratigraphy and structure of outcropping pre-Selma Coastal Plain beds of Fayette and Lamar Counties, Alabama

The Coastal Plain sediments of Fayette and Lamar Counties, Ala., are pre-Selma Late Cretaceous in age and are divided into three mappable units, from oldest to youngest: (i) the Coker formation, (2) the Gordo formation, and (3) a unit composed of the McShan and Eutaw formations undifferentiated. The Coker formation as here defined includes the Cottondale, Eoline, and Coker formations of earlier workers; the name Gordo is used as previously defined. The Coker and Gordo formations constitute the Tuscaloosa group. Structure contours on formational contacts locally show marked irregularities that are partly the result of structural disturbances. Some of these disturbances were probably of post-Morreville (post-Austin) age.

Circular↗
USGS2004

Development of a long-term sampling network to monitor restoration success in the southwest coastal Everglades: Vegetation, hydrology, and sediments

Introduction and History Hurricane Andrew, a Category 5 storm, crossed the southern Florida peninsula on the morning of August 24, 1992. Following the storm, the National Park Service conducted an environmental damage assessment to gauge the storm's impacts on the natural resources of south Florida Park Service holdings. Although hurricanes have impacted Park Service lands such as the Everglades in the past, no systematic, permanent sampling scheme has been established to monitor long-term recovery (or lack thereof) following disturbance. In October 1992, vegetation monitoring plots were established in heavily damaged areas of mangrove forest on the southwest coast of the Everlgades, along the Lostmans and Broad Rivers. As the permanent plot network was being established, funding was awarded for the South Florida Global Climate Change project (SOFL-GCC). This led to the establishment of a network of hydrological monitoring stations. Finally, sediment elevation tables (SETs) were installed at many locations. SETs provide the means to measure very small changes (2 mm) in the sediment surface elevation accurately over time. We also set up marker horizons to measure accretion of sediment at each site. Sampling sites were located along three transects extending from upstream freshwater wetlands to downstream saltwater wetlands along the Shark, Lostmans and Chatham Rivers in Everglades National Park. While we were developing our sampling network for basic scientific research needs, concern mounted over the health of the Greater Everglades Ecosystem and in particular over the influence of decreased freshwater flows. Ecosystem restoration planning was begun, resulting in the multi-agency, $8 billion Comprehensive Everglades Restoration Plan (CERP). Our co-located sampling networks allow us to track the interaction of hydrology, sediment, and vegetation over time, and will provide the opportunity to monitor the progress of the Everglades restoration and to gauge its success. Our earlier research questions have been modified over time to place a major emphasis on CERP needs, while still recognizing the importance of other processes, including disturbance and sea-level rise. Our research addresses processes relevant to the following restoration and related questions: * How will increasing freshwater flow affect wetland primary production? * Will increasing freshwater inflow alter nutrient availability? * Does recovery following disturbance in mangroves depend on freshwater inflow? * Will the position of vegetation ecotones change in response to upstream water management? * What will be the influence of global climate change, such as sea-level rise, on the Everglades restoration? * Will processes of wetlands soil formation be altered by sea-level rise and changed freshwater inflow?

Florida↗
USGS2018

Unmanned aerial systems capabilities of the U.S. Geological Survey Woods Hole Coastal and Marine Science Center

Unmanned aerial system (UAS) technology provides a rapid and low-cost solution for mapping coastal environments and assessing short- and long-term changes. The interdisciplinary nature of the data collected and the breadth of applications make UAS technology applicable to multiple scientific investigations. The Aerial Imaging and Mapping (AIM) group at the U.S. Geological Survey (USGS) Woods Hole Coastal and Marine Science Center provides UAS services to scientists to advance the science mission of the Coastal-Marine Hazards and Resources Program. Scientists at the Woods Hole Coastal and Marine Science Center use UASs to acquire imagery of coastal and wetland environments, which is then used to produce detailed topographic and visual reflectance datasets. UAS technology supports the work of geologists, engineers, physical scientists, geographers, and geochemists who study coastal erosion, sediment transport, storm impacts, habitats, biomass, and marsh stability.

Fact Sheet↗
USGS2026

Bascom Laser Diffraction Sedimentology Laboratory, Reston, Virginia

Introduction At the Bascom Laser Diffraction Sedimentology Laboratory, which is located in the Florence Bascom Geoscience Center at U.S. Geological Survey (USGS) headquarters in Reston, Virginia, scientists use physical sedimentology and particle characterization techniques to conduct detailed sediment characterization. Scientists address research problems in collaboration with other USGS science centers, State geological surveys, commercial industry, universities, and other partners. Laboratory capabilities include laser diffractometry for quantitative particle-size analysis, portable x-ray fluorescence (XRF) analysis for determining elemental abundances in rock or sediment samples, petrographic analysis of geologic media, and mechanical sieve analysis. These methods are used to analyze soil and sediment core material from terrestrial, marine, and lacustrine environments, surface sediments from coastal regions, and calcareous materials. Work done by the laboratory supports geologic mapping, resource assessments, land change studies, and geohazard analyses.

Fact Sheet↗
USGS2007

Coastal change-potential assessment of Sleeping Bear Dunes, Indiana Dunes, and Apostle Islands National Lakeshores to lake-level changes

A change-potential index (CPI) was used to map the susceptibility of the shoreline to future lake-level change within Apostle Islands, Indiana Dunes, and Sleeping Bear Dunes National Lakeshores (NL) along Lake Superior and Lake Michigan. The CPI in the Great Lakes setting ranks the following in terms of their physical contribution to lake-level related coastal change: geomorphology, regional coastal slope, rate and direction (i.e., rise and fall) of relative lake-level change, historical shoreline change rates, annual ice cover and mean significant wave height. The rankings for each input variable were combined, and an index value calculated for 1-minute bins covering the parks. The CPI highlights those regions where the physical effects of lake-level and coastal change might be the greatest. This approach combines the coastal system's potential for change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural susceptibility to the effects of lake-level variation. The CPI provides an objective technique for evaluation and long-term planning by scientists and park managers. The CPI is applied to the National Lakeshores of Apostle Islands, Indiana Dunes, and Sleeping Bear Dunes to test this methodology in lake settings. The National Lakeshores in this study consist of sand and gravel beaches, rock outcrops, and dune and glacial bluffs. The areas within these Great Lakes parks that are likely to experience the most lake-levelrelated coastal change are areas of unconsolidated sediment where regional coastal slope is low and wave energy is high.

Indiana, Michigan, Wisconsin↗
USGS2009

Sidescan-Sonar Imagery and Surficial Geologic Interpretations of the Sea Floor in Western Rhode Island Sound

The U.S. Geological Survey (USGS) and National Oceanic and Atmospheric Administration (NOAA) have been working together to interpret sea-floor geology along the northeastern coast of the United States. In 2004, the NOAA Ship RUDE completed survey H11322, a sidescan-sonar and bathymetric survey that covers about 60 square kilometers of the sea floor in western Rhode Island Sound. This report interprets sidescan-sonar and bathymetric data from NOAA survey H11322 to delineate sea-floor features and sedimentary environments in the study area. Paleozoic bedrock and Cretaceous Coastal Plain sediments in Rhode Island Sound underlie Pleistocene glacial drift that affects the distribution of surficial Holocene marine and transgressional sediments. The study area has three bathymetric highs separated by a channel system. Features and patterns in the sidescan-sonar imagery include low, moderate, and high backscatter; sand waves; scarps; erosional outliers; boulders; trawl marks; and dredge spoils. Four sedimentary environments in the study area, based on backscatter and bathymetric features, include those characterized by erosion or nondeposition, coarse-grained bedload transport, sorting and reworking, and deposition. Environments characterized by erosion or nondeposition and coarse-grained bedload transport are located in shallower areas and environments characterized by deposition are located in deeper areas; environments characterized by sorting and reworking processes are generally located at moderate depths.

Open-File Report↗
USGS2010

Geophysical Data Collected off the South Shore of Martha's Vineyard, Massachusetts

The U.S. Geological Survey Woods Hole Science Center conducted a nearshore geophysical survey offshore of the southern coast of Martha's Vineyard, in the vicinity of the Martha's Vineyard Coastal Observatory in 2007. This mapping program was part of a larger research effort supporting the Office of Naval Research Ripples Directed-Research Initiative studies at Martha's Vineyard Coastal Observatory designed to improve our understanding of coastal sediment-transport processes. The survey was conducted aboard the Megan T. Miller August 9-13, 2007. The study area covers 35 square kilometers from about 0.2 kilometers to 5 kilometers offshore of the south shore of Martha's Vineyard, and ranges in depth from ~6 to 24 meters. The geophysical mapping utilized the following suite of high-resolution instrumentation to map the surficial sediment distribution, bathymetry, and sub-surface geology: a dual-frequency 100/500 kilohertz sidescan-sonar system, 234 kilohertz interferometric sonar, and 500 hertz -12 kilohertz chirp subbottom profiler. These geophysical data will be used to provide initial conditions for wave and circulation modeling within the study area.

Open-File Report↗
USGS2011

Assessment of soil-gas, seep, and soil contamination at the North Range Road Landfill, Fort Gordon, Georgia, 2008-2009

Soil gas, seeps, and soil were assessed for contaminants at the North Range Road Landfill at Fort Gordon, Georgia, from October 2008 to September 2009. The assessment included delineating organic contaminants present in soil-gas samples beneath the area estimated to be the landfill and in water samples collected from three seeps at the base of the landfill. Inorganic contaminants were determined in three seep samples and in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. All soil-gas samples collected contained total petroleum hydrocarbons above the method detection level. The highest total petroleum hydrocarbon mass detected was nearly 50 micrograms (μg) in a soil-gas sample from one of the three seeps. The highest BTEX mass detected was 0.83 μg in a soil-gas sample collected near the same seep. Some soil-gas samples had perchloroethylene (known as PCE) mass greater than the method detection level of 0.01 microgram. The highest PCE mass detected was 0.73 μg, and PCE mass was detected in soil gas in areas upgradient of the seeps and indicates that the seep contamination may be related to previous waste-disposal activities upgradient of the seeps No organic or semivolatile compounds in the seep samples were detected above their respective maximum contaminant levels established in the U.S. Environmental Protection Agency National Primary Drinking Water Standards. PCE was detected in water from all three seeps at concentrations between 0.85 and 0.95 microgram per liter. Trimethylsilanol was detected in water collected from all three seeps and may be related to the degradation of silicone-based materials commonly disposed of in landfills. Inorganic concentrations in water samples from one seep did not exceed any maximum contaminant levels in the National Secondary Drinking Water Standards. In water from one seep, however, iron was detected at 865 micrograms per liter, which exceeds the maximum contaminant level for iron in the Secondary Drinking Water Standard, and in water from the other seep, iron and manganese were detected at 492,000 and 10,700 micrograms per liter, repectively, both of which exceed the respective maximum contaminant levels for the Secondary Drinking Water Standard. Water from one of the seeps had concentrations of cadmium, copper, and zinc that exceed Georgia standards for in-stream water quality, and concentrations of arsenic and lead that exceed their respective maximum contaminant levels for the Primary Drinking Water Standards. Inorganic concentrations in all four soil samples did not exceed regional screening levels established by the U.S. Environmental Protection Agency. Barium concentrations, however, were two to three times higher than the background concentrations reported in similar Coastal Plain sediments of South Carolina.

Open-File Report↗