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At least 559 records · Page 31Linked to original sources
USGS2022

Abundance of eelgrass (Zostera marina) at key Black Brant (Branta bernicla nigricans) wintering sites along the northern Pacific coast of Baja California, Mexico, 1998–2012

Trends in the abundance and distribution of eelgrass ( Zostera marina ), the primary winter forage of black brant ( Branta bernicla nigricans ), was evaluated at three major wintering sites for black brant along the northern Pacific coast of Baja California, Mexico. This region of northwestern Mexico contains significant beds of eelgrass that were showing signs of decline, which may negatively affect the Pacific flyway population of black brant. Embayment-wide surveys of eelgrass were conducted at Bahia San Quintin (BSQ), Laguna Ojo de Liebre (LOL), and Laguna San Ignacio (LSI) between 1998 and 2012 to estimate baselines and trends in the distribution and abundance of this seagrass in Mexico. Eelgrass was the most abundant and frequently encountered seagrass in each site across survey years. Density and aboveground biomass of eelgrass was greater in BSQ than in LOL and LSI while abundance of widgeongrass ( Ruppia maritima ), a secondary source of food for brant, was greatest in LSI across survey years. Widgeongrass occurred higher in the intertidal zone than did eelgrass in all embayments, and both seagrasses generally shifted to lower water depths along a southward latitudinal gradient. A negative temporal trend in abundance of seagrasses was detected in BSQ that appeared linked to impacts of climate warming and an increase in macroalgae populations. Decreases in abundance of seagrasses were also detected in LOL and LSI, although long-term trends were less certain in LOL. Overall, declines in abundance of eelgrass in Baja California may be influencing the ongoing shift in the winter distribution of brant to areas north of the Mexican border.

Baja California↗
USGS2026

Evaluation of benthic habitat change within the national historic sites of Hawaiʻi’s Kona Coast

Executive Summary Coral bleaching events have become increasingly common across the Hawaiian Archipelago since 1996 because of more frequent and intense marine heatwaves. The most significant bleaching event to date occurred from 2014 to 2015, which resulted in catastrophic state-wide coral loss. Bleaching events with less severe effects also occurred in 1996 and 2019. To understand the long-term effects of repeated bleaching events, along with other anthropogenic factors such as water quality, storms, sewage runoff, and coastal development, on coral reefs on the Kona Coast of the Island of Hawaiʻi, the U.S. Geological Survey, in collaboration with the National Park Service, collected underwater imagery in the early 2000s (baseline survey) and again in 2022 (resurvey). These images were captured within and adjacent to the National Historic Parks (NHP) and National Historic Sites (NHS) of Kaloko-Honokōhau NHP (KAHO), Puʻuhonua o Hōnaunau NHP (PUHO), and Puʻukohola Heiau NHS (PUHE). Imagery was classified for live coral cover and dominant type (four coral types, rubble, macroalgae, and two bottom substrate types). Change of percent live coral cover was determined for all sites. Change of coral and non-coral dominant types were calculated by aggregating classifications for each park into coral and non-coral. Net coral cover decreased between the baseline and resurvey period across all three parks, though PUHE exhibited the greatest loss of live coral cover. Across all three parks, the occurrence of lower coral cover classes (0–20 percent) increased and higher coral cover classes (greater than 50 percent) decreased. Furthermore, the total occurrence of non-coral dominant type classifications (rubble, macroalgae, sand, and volcanic pavement) increased by approximately 25 percent across all three parks, with PUHE experiencing a nearly 90-percent increase in the occurrence of non-coral types. There was little to no effect of water depth on change of live coral cover, indicating that marine heatwave driven bleaching events and additional anthropogenic influences affected the entire reef across all water depths from the lower fore reef to the reef flat. Because coral loss was more severe at PUHE and PUHO than KAHO, creating a monitoring framework that utilizes periodic underwater camera surveys and fixed diver transects by the National Park Service would contextualize the periodic spatial surveys to the fixed transects that have greater temporal resolution. Similarly, increased frequency of spatial surveys would allow for the National Park Service to continue monitoring changes to critical nearshore habitats and marine resources relevant to National Park jurisdiction.

Hawaii↗
USGS1969

Sedimentary rocks of the coast of Liberia

Two basins containing sedimentary rocks o# probable Cretaceous age have been recognized near the coast of Liberia in the area between Monrovia and Buchanan; geophysical evidence suggests that similar though larger basins exist on the adjacent continental shelf. The oldest sedimentary unit recognized, the Paynesville Sandstone of possible early to middle Paleozoic age, is intruded by dikes and sills of diabase of early Jurassic age and lies unconformably on crystalline rocks of late Precambrian age. Dips in the Paynesville Sandstone define a structural basin centered south of Roberts International Airport (formerly called Roberts Field) about 25 miles east of Monrovla. Wackes and conglomerates of Cretaceous age, herein named the Farmington River Formation, unconformably overlie the Paynesville Sandstone and constitute the sedimentary fill in the Roberts basin. The Bassa basin lies to the southeast of the Roberts basin and is separated from it by an upwarp of crystalline rocks. The basin is occupied by wackes and conglomerates of the Farmington River Formation, which apparently lie directly on the crystalline basement. Both basins are bounded on the northeast by northwest-trending dip-slip faults. The best potential for petroleum deposits that exists in Liberia is beneath the adjacent continental shelf and slope. Geophysical exploration and drilling will be required to evaluate this potential.

Open-File Report↗
USGS1970

A gravity and aeromagnetic survey of the mid-Tertiary sedimentary basin on the south coast of Puerto Rico

During the period November 18, 1963 to December 3, 1963 the U.S. Geological Survey in cooperation with the Commonwealth of Puerto Rico performed a gravity survey of the Tertiary sedimentary basin which is located along the south coast of Puerto Rico in the vicinity of Ponce. The project was initiated at the request of Mr. Carlos Vincenty, Director, Department of Industrial Research, Economic Development Administration of the Commonwealth of Puerto Rico. The purpose of the survey was to obtain information on the configuration arid structure of the basin and if possible, to locate areas which might be favorable for the accumulation of oil or gas. The accompanying index map (fig. 1) shows the survey area together with the outline of the border of the basin.

Puerto Rico↗
USGS1974

Faults related to seismicity off the coast of South Carolina

Seismic reflection profiles taken parallel to the continental margin off the coast of South Carolina show that faults probably are present in the Tertiary rocks of the margin and that they are located on the trend of seismic activity which passes through the state.

South Carolina↗
USGS1978

Neogene biostratigraphy of selected areas in the California Coast Ranges

These papers on the marine Neogene (Miocene and Pliocene) of California are intended to provide orientation and documentation for a field conference on the Neogene biostratigraphy of the California Coast Ranges. They also constitute status reports on the age and correlation of key sections in Neogene basins of coastal California. Many new biostratigraphic data, particularly on planktic microfossils, are incorporated in these resumes.

California↗
USGS1979

Ground-water levels in alluvium on the South coast of Puerto Rico, February 1978

Ground-water levels in the alluvial aquifer of the south coast of Puerto Rico in February 1978 were similar to or slightly higher than those of February 1977. Water levels rose about 2 to 3 meters in the northern section near the foothills in the coastal plain area from Salinas to Patillas and in the Guanica-Penuelas area. Pumpage remained unchanged in most of the areas under study. Pumping-water levels were above mean sea level in all industrial well fields. Pumping and static water levels were below mean sea level (1 to 3 meters), in public supply and irrigation wells in the areas of Playa de Ponce, Descalabrado-Punta Petrona, and in the vicinity of the town of Salinas. These levels are considered to be normal for the dry season in these highly irrigated areas. Sixty-four water samples collected from irrigation, industrial and salinity observation wells exhibited similar or lower chloride concentration than in previous years. The average chloride concentration for 1978 was 57 milligrams per liter. (USGS)

Open-File Report↗
USGS1979

Seawater intrusion, south coast of Puerto Rico, 1966-77

A salinity reconnaissance of the south coast alluvial aquifer of Puerto Rico, including the areas of Guenica, Guayanilla-Yauco, Tallaboa, Juana Diaz, and Jobos was made during 1966-68. In this investigation seawater was detected in the Guayanilla-Yauco and Tallaboa areas. Since 1968, water level and quality-of-water data have been collected from selected wells in the south coastal areas between Guanica and Patillas. The 1968-77 study indicated two additional areas of possible seawater intrusion in the Ponce-Santa Isabel area. Another area of possible seawater intrusion was found in the southeastern section of the Salinas fan in the Jobos area.

Puerto Rico↗
USGS1979

Hydrologic and geologic data from the Upper East Coast Planning Area, southeast Florida

The Upper East Coast Planning Area, one of five designated planning areas in the South Florida Water Management District, consists of St. Lucie, Martin, and eastern Okeechobee Counties. Existing hydrologic and geologic data have been compiled as a base for additional investigations to determine the water-bearing characteristics of the shallow aquifer system in the area. These data include lithologic logs from 51 wells in excess of 90 feet in depth, periodic ground-water levels from 100 wells, and ground-water levels from 100 wells, and ground-water quality data from 93 wells. (Kosco-USGS)

Florida↗
USGS1980

Geologic aspects of the surficial aquifer in the upper East Coast planning area, Southeast Florida

The Upper East Coast Planning Area, as designated by the South Florida Water Management District, consists of St. Lucie County, Martin County, and eastern Okeechobee County. The surficial aquifer is the main source of freshwater for agricultural and urban uses in the area. The geologic framework of the aquifer is displayed by contour mapping and lithologic cross sections to provide water managers with a better understanding of the natural restraints that may be imposed on future development. The surficial aquifer is primarily sand, limestone, shell, silt, and clay deposited during the Pleistocene and Pliocene Epochs. The aquifer is unconfined and under water-table conditions in most of the area, but locally, artesian conditions exits where discontinuous clay layers act as confining units. Impermeable and semipermeable clays and marls of the Tamiami (lower Pliocene) and Hawthorn Formations (Miocene) unconformably underlie the surficial aquifer and form its base. Contour lines showing the altitude of the base of the aquifer indicate extensive erosion of the Miocene sediments prior to deposition of the aquifer materials. (USGS)

Open-File Report↗
USGS1982

Water use in the Mississippi Gulf Coast counties, 1980

The population served by public water systems in the three counties of Mississippi 's Gulf Coast increased from about 227 ,000 to nearly 253,000 between 1975 and 1980. Water use by public systems increased from about 27.6 million gallons per day to more than 31.3 million gallons per day. Self-supplied industrial use of ground water decreased from about 18.4 to 17.7 million per day, and that for fresh surface water increased from about 42.3 to 56.1 million gallons per day. Total freshwater was including that for rural domestic supplies, increased from about 92.0 to 109 million gallons per day. Industrial use of brackish surface water decreased from about 790 to 660 million gallons per day. (USGS)

Open-File Report↗
USGS1996

Description of wells drilled at the U.S. Coast Guard Support Center Kodiak, Alaska, 1988-89

The U.S Coast Guard, in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act and the Resource Conservation and Recovery Act, is conducting environmental studies at its Support Center in Kodiak, Alaska, to determine if hazardous materials have been spilled or disposed of at the facility. The U.S. Geological Survey conducted a hydrologic evaluation of the Support Center to assess the extent of possible ground-water, surface-water, and soil contamination resulting from the handling of hazardous materials. This report describes the borehole and monitoring-well drilling program conducted on the Support Center by the U.S. Geological Survey. It contains maps and diagrams depicting well locations, logs, and construction details, as well as soil-sampling information for 121 boreholes, of which 102 were completed as water-quality monitoring wells.

Open-File Report↗
USGS1996

Overview of surface-water resources at the U.S. Coast Guard Support Center Kodiak, Alaska, 1987-89

Hydrologic data at a U.S. Coast Guard Support Center on Kodiak Island, Alaska, were collected from 1987 though 1989 to determine hydrologic conditions and if contamination of soils, ground water, or surface water has occurred. This report summarizes the surface-water-discharge data collected during the study and estimates peak, average, and low-flow values for Buskin River near its mouth. Water-discharge measurements were made at least once at 48 sites on streams in or near the Center. Discharges were measured in the Buskin River near its mouth five times during 1987-89 and ranged from 27 to 367 cubic feet per second. Tributaries of Buskin River below Buskin Lake that had discharges greater than 1 cubic foot per second include Bear Creek, Alder Creek, Magazine Creek, Devils Creek and an outlet from Lake Louise. Streams having flows generally greater than 0.1 cubic foot per second but less than 1 cubic foot per second include an unnamed tributary to Buskin River, an unnamed tributary to Lake Catherine and a drainage channel at Kodiak airport. Most other streams flowing into Buskin River, and all streams on Nyman Peninsula, usually had little or no flow except during periods of rainfall or snowmelt. During a low-flow period in February 1989, discharge measurements in Buskin River and its tributaries indicate that three reaches of Buskin River below Buskin Lake lost water to the ground-water system, whereas two reaches gained water; the net gain in streamflow attributed to ground-water inflow at a location near the mouth was estimated to be 2.2 cubic feet per second. The 100-year peak flow for Buskin River near its mouth was estimated to be 4,460 cubic feet per second. Average discharge was estimated to be 125 cubic feet per second and the 7-day 10-year low flow was estimated to be 5.8 cubic feet per second.

Alaska↗
USGS1996

Hydrologic and water-quality data for U.S. Coast Guard Support Center Kodiak, Alaska, 1987-89

Hydrologic and water-quality data were collected at the U.S. Coast Guard Support Center Kodiak on Kodiak Island, Alaska, to determine regional ground-water conditions and if contamination of soils, ground water, or surface water has occurred. Eighteen areas of possible contamination were identified. Ground-water levels, surface- water stages, surface-water discharges, and results of field and laboratory analyses of soil and water samples are presented in tabular form. Many quality-assurance samples had detectable concentrations of methylene chloride and 1,2-dichloroethane, which may be due to sampling or laboratory contamination. Concentrations were as great as 5.9 micrograms per liter for methylene chloride and 2.6 micrograms per liter for 1,2-dichloroethane. Excluding 1,2-dichloroethane, most soil, ground-water, and surface-water samples contained no detectable concentrations of the organic constituents that were analyzed. Chemical analyses were performed on two lake-bed-material samples and more than 100 soil samples. The median lead concentration was 9.8 milligrams per kilogram. Concentrations of tetrachloroethene were as great as 1.1 milligram per kilogram in soils near a laundry. Water samples were collected from 101 wells. The maximum benzene concentration detected in ground water was 78 micrograms per liter from a well at the air station near a site where aviation fuel was spilled. Wells near a laundry yielded water having concentrations of tetrachloroethene as great as 3,000 micrograms per liter, and vinyl chloride as great as 440 micrograms per liter. A well in a former aviation gasoline storage area yielded water with a concentration of trichloroethene as great as 66 micrograms per liter. Water samples were collected from 59 sites on streams, lakes, or ponds. Surface-water samples had much lower concen- trations of organic compounds; the highest concentration of benzene was 2.2 micrograms per liter in a stream near a former aviation-fuel storage area and the maximum vinyl chloride concentration was 15 micrograms per liter in a stream near a former landfill. Tetrachloroethene and trichloroethene were not detected in any surface-water samples.

Open-File Report↗
USGS1997

Geophysical database of the east coast of the United States; southern Atlantic margin, stratigraphy and velocity in map grids

In 1990, the Naval Oceanographic Office and the U.S. Geological Survey agreed to develop a digital data base of stratigraphy and acoustic properties of sediments along the U.S. East Coast of the United States. The objective of this work was to utilize more than 25,000 km of publicly available multichannel seismic-reflection profiles (Sheridan et al., 1988) in order to assign acoustic properties to the continental margin postrift sediments in an internally consistent, geologically meaningful, regionally extensive, digital form. The acoustic properties of interest include thickness, depth, compressional- and shear-wave velocity, compressional- and shear-wave attenuation, density, and lithology. This data base subdivides the 0- to 14-km thick Jurassic and younger postrift deposits into 18 mappable horizons. The spatial scale of gridding is 5' latitude by 5 ' longitude, or about 9x8 km. This report describes the second part of developing the data base for the continental margin between Florida and Cape Hatteras: spatial gridding of the digital stratigraphic and velocity data, derivative calculations of density, shear-wave velocity, and attenuation, and construction of the final data base. The first report (Hutchinson et al., 1995) describes how the stratigraphy and velocity were digitized from the original profiles. Complementary reports that describe the data base for the area between Cape Hatteras and Georges Bank are given in Klitgord and Schneider (1994) and Klitgord et al. (1994).

Open-File Report↗
USGS1997

Map showing outcrop of the coal-bearing units and land use in the Gulf Coast region

This map is a preliminary compilation of the outcrop geology of the known coal-bearing units in the Gulf Coast Coal region. The map has been compiled for use in the National Coal Resource Assessment Project currently being conducted by the U.S. Geological Survey, and will be updated as the assessment progresses. The purpose of the map is to show the distribution of coal-bearing rocks in the Gulf Coastal Plain Region and to show stratigraphic correlations, transportation network, fossil-fuel burning power plants, and federally managed lands in the region. It is hoped that this map may aid coal exploration and development in the region. Geologic contacts were digitized from paper copies of the maps listed in the reference section below. The primary source of information was the 1:500,000-scale state geology map series, but larger scale maps were use to better define certain areas, notably the Jackson-Claiborne contact in western Kentucky and Tennessee for example (Olive, 1980). Contacts along state boundaries were modified to best-fit information available from the border areas. Note that coal distribution in the mapped units is not uniform. For example, the Jackson Group contains coal in Texas, but in Mississippi is not presently known to contain significant coal deposits. The unit is widespread and in part non-marine and thus of potential future interest. In contrast, the Jackson Group is not shown in Georgia where it is mostly marine and residuum (weathered material) at the surface. Tertiary age coal has also been noted in the Vicksburg Group (Oligocene) of Louisiana and Mississippi, but is not shown on this map. Contacts with mapped surficial units are not always shown. The locations of coal mine permit boundaries are based on information available at the time of publication and were obtained from the Division of Surface Mining and Reclamation, Railroad Commission of Texas, Austin, and the Injection and Mining Division, Department of Natural Resources, Baton Rouge, Louisiana. The correlation of map units and formation names generally follow Galloway and others (1991). We have placed the Paleocene-Eocene boundary in the middle of the Calvert Bluff Formation in Texas based on unpublished pollen biostratigraphy reports (N.O. Fredericksen, unpublished data, 1993; D.J. Nichols, unpublished data, 1996).

Alabama, Arkansas, Georgia, Florida, Kansas, Kentu↗
USGS1999

Modified Mercalli intensities for some California north-coast earthquakes

Modified Mercalli Intensity (MMI) data are used by Bakun (in preparation) to estimate the location and moment magnitude M of California north-coast earthquakes from MMI observations only. The MMI data and site corrections used by Bakun (in preparation) are listed in this Open-file Report. This report is also accessible at http://quake.wr.usgs.gov/~bakun/.

Open-File Report↗
USGS1983

Studies in Tertiary stratigraphy of the California Coast Ranges

The correlation of rocks of Paleogene age in California with those in Europe has had a long and complex history that can only be highlighted here. Kleinpell (1938, p. 168-181), in his classic work defining Miocene benthic1 foraminiferal stages of California, attempted to correlate faunas of California with those of western Europe and elsewhere. He pointed out that rocks usually considered lower Miocene in California are probably correlative with those considered Oligocene in Europe. Schenck and Childs (1942) correlated the Vaqueros Sandstone of California with the middle and upper Oligocene of Europe and elsewhere, based on the stratigraphic occurrence of Lepidocyclina. Their correlation was discussed extensively by a number of paleontologists in the same report. Some favored a Miocene age based on similarities of the Vaqueros molluscan fauna with the Burdigalian faunas of Europe, and on the apparent Miocene age of vertebrates from beds below the Vaqueros. Others argued that some of the mollusks in the Vaqueros were similar to those considered Oligocene in Trinidad, and that the percentage of living mollusks in the Vaqueros Sandstone (1-2 percent) was most similar to faunas of Oligocene age. These differences in opinion proved to be irreconcilable in the attempt by the U.S. Committee on Stratigraphy to provide a standard correlation chart for marine Cenozoic formations of western North America (Weaver and others, 1944). Two standards had to be provided, one based largely on mollusks, echinoids, and corals, and the other on benthic foraminifers. This dual classification has persisted almost to the present. The validity of some California Tertiary stages · based largely on benthic foraminifers .has been questioned in recent years. Pierce (1972) and Barron (1976) believed that the Delmontian Stage of Kleinpell (1938), for example, is coeval with the lower and middle part of his Mohnian Stage. Steineck and Gibson (1971), Gibson and Steineck (1972), Schmidt (1975), Bandy (1972) and Bukry, Brabb, and Vedder (1977) stated their belief that probably all of the California Paleocene and Eocene stages of Mallory (1959) are time-transgressive when compared to nannoplankton and planktonic foraminifer zonations. Hornaday and Philips (1972), on the other hand, challenged some of these opinions. In order to further the study of the relation between California Paleogene stages based on benthic foraminifers with zonations based on planktic foraminifers and nannoplankton, nine paleontologists were invited to examine the faunas from several Coast Range sections measured by Brabb, Clark, and Throckmorton (1977). The results of their investigation were presented orally at a meeting of the International Subcommission on Paleogene Stratigraphy in Menlo Park, California on October 28, 1977. The talks were preceded by three days of field trips to the measured sections and were followed by a microscope workshop to debate the identification and age of the various faunas. The paleontologists were then encouraged to submit papers for this volume, and all have graciously complied.

California↗