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At least 109 records · Page 6Linked to original sources
USGS2024

Modeling the potential spread of the non-native regal demoiselle, Neopomacentrus cyanomos, in the western Atlantic

Predicting the potential distribution of a non-native species can assist management efforts to mitigate impacts on recipient ecosystems. However, such predictions are lacking for marine species, such as the non-native regal demoiselle, Neopomacentrus cyanomos , that is currently expanding its distribution in the western Atlantic. We used correlative species distribution models with three common algorithms to predict suitable habitat for N. cyanomos in the region. We compared models developed using native, non-native, and global occurrences to differentiate drivers across separate ranges using a suite of 12 environmental characteristics. While final models included an ensemble of variables, the majority ranked the combined effect of temperature variables as a key predictor correlated with the distribution of N. cyanomos. Habitat suitability increased as water temperatures increased beyond 16 °C and where annual thermal ranges were greater than 10 °C at the shallowest depth with substrate within a study cell (~ 9.2 km 2 resolution). Habitat suitability also increased where maximum surface temperatures were greater than 27 °C. In the non-native range, the proportion of reef available in each cell was another important variable increasing the suitable habitat for N. cyanomos . Our models predicted high habitat suitability for N. cyanomos throughout the Greater Caribbean, in higher latitudes along North and South American Atlantic coasts, in the eastern Pacific Ocean, and highlights key areas where managers can monitor and target potential removal efforts. The distribution of this non-native species is likely to continue expanding throughout the region with little known about potential implications on native communities.

Coral Reefs↗
USGS2023

Organohalogenated contaminants in multiple life stages of the Pacific lamprey (Entosphenus tridentatus), Oregon, USA

Pacific lamprey (Entosphenus tridentatus) are ecologically and culturally important anadromous animals native to the West Coast of the United States. Pacific lamprey populations are in decline, and contaminants may be a contributing factor. Between 2017 and 2021, three life stages of Pacific lamprey and collocated sediment samples were collected in Oregon (larval lamprey, sediment, and returning adult lamprey) and off the coast of Oregon and Washington (ocean juvenile lamprey). Tissue and sediment samples were analyzed for 56 organohalogenated compounds that included legacy pesticides, current use pesticides, polybrominated diphenyl ether congeners, and polychlorinated biphenyl congeners. Organohalogenated compounds were detected in all three Pacific lamprey life stages. The organohalogenated compounds detected in collocated sediment and larval lamprey samples were generally dissimilar, and compounds detected in larval lamprey indicate potential point sources along the rivers. Ocean-caught juvenile lamprey had significantly higher lipid contents than returning adult lamprey, but lipid content and concentrations of select compounds were not strongly correlated. Concentrations of select compounds detected in both ocean juvenile and returning adult lamprey were either not significantly different or were higher in returning adult lamprey. Concentrations of some compounds in returning adult lamprey—which are consumed by Indigenous peoples—exceeded state and national human health consumption thresholds. Collaboration among Tribes and public-sector agencies helped make this study successful.

Oregon↗
USGS2008

Medieval forewarning of the 2004 Indian Ocean tsunami in Thailand

Recent centuries provide no precedent for the 2004 Indian Ocean tsunami, either on the coasts it devastated or within its source area. The tsunami claimed nearly all of its victims on shores that had gone 200 years or more without a tsunami disaster. The associated earthquake of magnitude 9.2 defied a Sumatra-Andaman catalogue that contains no nineteenth-century or twentieth-century earthquake larger than magnitude 7.9 (ref. 2). The tsunami and the earthquake together resulted from a fault rupture 1,500 km long that expended centuries' worth of plate convergence. Here, using sedimentary evidence for tsunamis, we identify probable precedents for the 2004 tsunami at a grassy beach-ridge plain 125 km north of Phuket. The 2004 tsunami, running 2 km across this plain, coated the ridges and intervening swales with a sheet of sand commonly 5-20 cm thick. The peaty soils of two marshy swales preserve the remains of several earlier sand sheets less than 2,800 years old. If responsible for the youngest of these pre-2004 sand sheets, the most recent full-size predecessor to the 2004 tsunami occurred about 550-700 years ago. ??2008 Macmillan Publishers Limited. All rights reserved.

Nature↗
USGS2009

The Columbia River Basalt Group: from the gorge to the sea

Miocene flood basalts of the Columbia River Basalt Group inundated eastern Washington, Oregon, and adjacent Idaho between 17 and 6 Ma. Some of the more voluminous flows followed the ancestral Columbia River across the Cascade arc, Puget-Willamette trough, and the Coast Range to the Pacific Ocean. We have used field mapping, chemistry, and paleomagnetic directions to trace individual flows and flow packages from the Columbia River Gorge westward into the Astoria Basin, where they form pillow palagonite complexes and mega-invasive bodies into older marine sedimentary rocks. Flows of the Grande Ronde, Wanapum, and Saddle Mountains Basalts all made it to the ocean; at least 33 flows are recognized in the western Columbia River Gorge, 50 in the Willamette Valley, 16 in the lower Columbia River Valley, and at least 12 on the Oregon side of the Astoria Basin. In the Astoria Basin, the basalt flows loaded and invaded the wet marine sediments, producing peperite breccias, soft sediment deformation, and complex invasive relations. Mega-invasive sills up to 500 m thick were emplaced into strata as old as Eocene, and invasive dikes up to 90 m thick can be traced continuously for 25 km near the basin margin. Mega-pillow complexes up to a kilometer thick are interpreted as the remains of lava deltas that prograded onto the shelf and a filled submarine canyon southeast of Astoria, possibly providing the hydraulic head for injection of invasive sills and dikes at depth.

Oregon;Washington↗
USGS2001

Miocene and early Pliocene epithermal gold-silver deposits in the northern Great Basin, western United States: Characteristics, distribution, and relationship to Magmatism

Numerous important Miocene and early Pliocene epithermal Au-Ag deposits are present in the northern Great Basin. Most deposits are spatially and temporally related to two magmatic assemblages: bimodal basalt-rhyolite and western andesite. These magmatic assemblages are petrogenetic suites that reflect variations in tectonic environment of magma generation. The bimodal assemblage is a K-rich tholeiitic series formed during continental rifting. Rocks in the bimodal assemblage consist mostly of basalt to andesite and rhyolite compositions that generally contain anhydrous and reduced mineral assemblages (e.g., quartz + fayalite rhyolites). Eruptive forms include mafic lava flows, dikes, cinder and/or spatter cones, shield volcanoes, silicic flows, domes, and ash-flow calderas. Fe-Ti oxide barometry indicates oxygen fugacities between the magnetite-wustite and fayalite-magnetite-quartz oxygen buffers for this magmatic assemblage. The western andesite assemblage is a high K calc-alkaline series that formed a continental-margin are related to subduction of oceanic crust beneath the western coast of North America. In the northern Great Basin, most of the western andesite assemblage was erupted in the Walker Lane belt, a zone of transtension and strike-slip faulting. The western andesite assemblage consists of stratovolcanoes, dome fields, and subvolcanic plutons, mostly of andesite and dacite composition. Biotite and hornblende phenocrysts are abundant in these rocks. Oxygen fugacities of the western andesite assemblage magmas were between the nickel-nickel oxide and hematite-magnetite buffers, about two to four orders of magnitude greater than magmas of the bimodal assemblage. Numerous low-sulfidation Au-Ag deposits in the bimodal assemblage include deposits in the Midas (Ken Snyder), Sleeper, DeLamar, Mule Canyon, Buckhorn, National, Hog Ranch, Ivanhoe, and Jarbidge districts; high-sulfidation gold and porphyry copper-gold deposits are absent. Both high- and low-sulfidation gold-silver and porphyry copper-gold deposits are affiliated with the western andesite assemblage and include the Comstock Lode, Tonopah, Goldfield, Aurora, Bodie, Paradise Peak, and Rawhide deposits. Low-sulfidation Au-Ag deposits in the bimodal assemblage formed under relatively low oxygen and sulfur fugacities and have generally low total base metal (Cu + Pb + Zn) contents, low Ag/Au ratios, and notably high selenide mineral contents compared to temporally equivalent low-sulfidation deposits in the western andesite assemblage. Petrologic studies suggest that these differences may reflect variations in the magmatic-tectonic settings of the associated magmatic assemblages-deposits in the western andesite assemblage formed from oxidized, water-rich, subduction-related calc-alkaline magmas, whereas deposits in the bimodal assemblage were associated with reduced, water-poor tholeiitic magmas derived from the lithospheric mantle during continental extension. The contrasting types and characteristics of epithermal deposits and their affinities with associated igneous rocks suggest that a genetic relationship is present between these Au-Ag deposits and their temporally associated magmatism, although available data do not prove this relationship for most low-sulfidation deposits.

Economic Geology↗
USGS2009

Archive of digital boomer seismic reflection data collected offshore east-central Florida during USGS cruise 00FGS01, July 14-22, 2000

In July of 2000, the U.S. Geological Survey (USGS), in cooperation with the Florida Geological Survey (FGS), conducted a geophysical survey of the Atlantic Ocean offshore Florida's east coast from Brevard County to northern Martin County. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, Geographic Information System (GIS) information, digital and handwritten Field Activity Collection System (FACS) logs, and Federal Geographic Data Committee (FGDC) metadata. A filtered and gained (a relative increase in signal amplitude) digital image of each seismic profile is also provided. Refer to the Acronyms page for expansions of all acronyms and abbreviations used in this report. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU) (Cohen and Stockwell, 2005). Example SU processing scripts and USGS Software for viewing the SEG-Y files (Zihlman, 1992) are also provided. The USGS St. Petersburg Coastal and Marine Science Center assigns a unique identifier to each cruise or field activity. For example, 00FGS01 tells us the data were collected in 2000 for cooperative work with the Florida Geological Survey (FGS) and the data were collected during the first field activity for that study in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the field activity ID. The boomer plate is an acoustic energy source that consists of capacitors charged to a high voltage and discharged through a transducer in the water. The transducer is towed on a sled floating on the water surface and when discharged, emits a short acoustic pulse, or shot, which propagates through the water, sediment column, or rock beneath. The acoustic energy is reflected at density boundaries (such as the seafloor, sediment, or rock layers beneath the seafloor), detected by the receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). In this way, a two-dimensional (2D) vertical profile of the shallow geologic structure beneath the ship track is produced. Figure 1 displays the acquisition geometry. Refer to table 1 for a summary of acquisition parameters. The unprocessed seismic data are stored in SEG-Y format (Barry and others, 1975). For a detailed description of the data format, refer to the SEG-Y Format page. See the How To Download SEG-Y Data page for download instructions. The printable profiles provided are GIF images that were filtered and gained using Seismic Unix software. Refer to the Software page for details about the processing and examples of the processing scripts. The printable profiles can be viewed from the Profiles page or from links located on the trackline maps. To view the trackline maps and navigation files, and for more information about these items, see the Navigation page. Detailed information about the navigation system used can be found in table 1. Of a total record length of 200 ms, only the upper 100 ms of each profile are displayed because no useful information was observed deeper in the sections. A 10 ms deep water delay appears on lines b57-b63 and sl2-sl28. No digital data were collected for line sl6. However, line sl6r is a second attempt to collect digital data for this line. Digital data and 500-shot-interval location navigation are not available for the last 1,161 shots of line sl26 due to an equipment malfunction.

Florida↗
USGS1990

Coastal barrier resources system mapping process

The Coastal Barrier Resources Act of 1982 (P.L. 97-348) established the Coastal Barrier Resources System (system), a 452,834 acre system of undeveloped, unprotected coastal barriers along 666 shoreline miles of the Atlantic Ocean and Gulf of Mexico coasts. Within the 186 unites of the Coastal Barrier Resources System, most Federal expenditures that encourage development are prohibited. Section 10 of the act directed the Department of the Interior (DOI) to conduct a study and prepare a report to Congress on the Coastal Barrier Resources System. The report, delivered to Congress in December 1988, recommended additions to, or deletions from, the Coastal Barrier Resources System, and listed modifications to the boundaries of system units. The DOI's recommendations, if passed by Congress, would add about 790,884 acres and 423 miles of shoreline to the Coastal Barrier Resources System. The coastal barriers included in the Coastal Barrier Resources System by Congress in 1982 were designated based on definitions and delineation criteria development by the DOI in 1981-82. The criteria used by the DOI to delineate barriers included in the 1988 recommendations to Congress differed from those used in 1981 in several respects, reflecting advances in the scientific understanding of coastal barriers, and the functional requirements of a good definition. I outline the mapping criteria used in 1981-82 and in 1984-87 during the Section 10 study. I also discuss some of the problems encountered in consistently identifying and delineating features across a heterogeneous national coastline, and I comment on future reinventories of coastal barriers.

Biological Report - US Fish & Wildlife Service↗
USGS2006

The National Assessment of Shoreline Change: A GIS compilation of vector shorelines and associated shoreline change data for the sandy shorelines of the California coast

Introduction The Coastal and Marine Geology Program of the U.S. Geological Survey has generated a comprehensive data clearinghouse of digital vector shorelines and shoreline change rates for the sandy shoreline along the California open coast. These data, which are presented herein, were compiled as part of the U.S. Geological Survey's National Assessment of Shoreline Change Project. Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information including rates and trends of shoreline migration. There is also a critical need for shoreline change data that is consistent from one coastal region to another. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, and internally consistent updates of shorelines and shoreline change rates can be made at a National Scale. This data compilation for open-ocean, sandy shorelines of the California coast is one in a series that already includes the Gulf of Mexico and the Southeast Atlantic Coast (Morton et al., 2004; Morton et al., 2005) and will eventually cover Washington, Oregon, and parts of Hawaii and Alaska. Short- and long-term shoreline change evaluations are determined by comparing the positions of three historical shorelines digitized from maps, with a modern shoreline derived from LIDAR (light detection and ranging) topographic surveys. Historical shorelines generally represent the following time-periods: 1850s-1880s, 1920s-1930s, and late 1940s-1970s. The most recent shoreline is from data collected between 1997 and 2002. Long-term rates of change are calculated by linear regression using all four shorelines. Short-term rates of change are end-point rate calculations using the two most recent shorelines. Please refer to our full report on shoreline change of the California coastline at http://pubs.usgs.gov/of/2006/1219/ for additional information regarding methods and results (Hapke et al., 2006). Data in this report are organized into downloadable layers by region (Northern, Central and Southern California) and are provided as vector datasets with metadata. Vector shorelines may represent a compilation of data from one or more sources and these sources are included in the dataset metadata. This project employs the Environmental Systems Research Institute's (ESRI) ArcGIS as it's GIS mapping tool and contains several data layers (shapefiles) that are used to create a geographic view of the California Coast. These vector data form a basemap comprised of polygon and line themes that include a U.S. coastline (1:80,000), U.S. cities, and state boundaries.

California↗
USGS2013

Statewide summary for Florida

Throughout the past century, emergent wetlands have been declining across the Gulf of Mexico. Emergent wetland ecosystems provide a multitude of resources, including plant and wildlife habitat, commercial and recreational economic activity, and natural barriers against storms. As emergent wetland losses increase, so does the need for information on the causes and effects of this loss; emergent wetland mapping, monitoring, and restoration efforts; and education. This report provides scientists, managers, and citizens with valuable baseline information on the status and trends of emergent wetlands along the coast of the Gulf of Mexico. The Statewide Summary for Florida provides status and trends information for Florida using what data is available during the 1950-2010 time period. The State of Florida (Figure 1) is approximately 151,670 km2 (58,560 mi2 ) large with an average elevation of 30.5 m (100 ft) (Dahl, 2005). The Florida gulf coast stretches approximately 1,000 km (621 miles) from the Alabama State line to the Dry Tortugas in the Florida Keys (Handley et al., 2007). The climate varies along the coast, ranging from temperate continental in the panhandle to oceanic subtropical in the Keys. Due to this climatic gradient, the Gulf coast of Florida is divisible into two ecoregions, the Louisianian in the north along the panhandle, and the West Indian in the south along the length of the peninsula (Bailey 1978). The Lousianian ecoregion extends from Cedar Key north and west along the panhandle to the Alabama state line. It is characterized by extensive emergent coastal wetlands, temperate fauna, small tidal ranges (

Florida↗
USGS2011

Lidar-revised geologic map of the Uncas 7.5' quadrangle, Clallam and Jefferson Counties, Washington

In 2000 and 2001, the Puget Sound Lidar Consortium obtained 1 pulse/m 2 lidar data for about 65 percent of the Uncas 7.5' quadrangle. For a brief description of LIDAR (LIght Detection And Ranging) and this data acquisition program, see Haugerud and others (2003). This map combines geologic interpretation (mostly by Haugerud and Tabor) of the 6-ft (2-m) lidar-derived digital elevation model (DEM) with the geology depicted on the Preliminary Geologic Map of the Uncas 7.5' Quadrangle, Clallam and Jefferson Counties, Washington, by Peter J. Haeussler and others (1999). The Uncas quadrangle in the northeastern Olympic Peninsula covers the transition from the accreted terranes of the Olympic Mountains on the west to the Tertiary and Quaternary basin fills of the Puget Lowland to the east. Elevations in the map area range from sea level at Port Discovery to 4,116 ft (1,255 m) on the flank of the Olympic Mountains to the southwest. Previous geologic mapping within and marginal to the Uncas quadrangle includes reports by Cady and others (1972), Brown and others (1960), Tabor and Cady (1978a), Yount and Gower (1991), and Yount and others (1993). Paleontologic and stratigraphic investigations by University of Washington graduate students (Allison, 1959; Thoms, 1959; Sherman, 1960; Hamlin, 1962; Spencer, 1984) also encompass parts of the Uncas quadrangle. Haeussler and Wells mapped in February 1998, following preliminary mapping by Yount and Gower in 1976 and 1979. The description of surficial map units follows Yount and others (1993) and Booth and Waldron (2004). Bedrock map units are modified from Yount and Gower (1991) and Spencer (1984). We used the geologic time scale of Gradstein and others (2005). The Uncas quadrangle lies in the forearc of the Cascadia subduction zone, about 6.25 mi (10 km) east of the Cascadia accretionary complex exposed in the core of the Olympic Mountains (Tabor and Cady, 1978b). Underthrusting of the accretionary complex beneath the forearc uplifted and tilted eastward the Coast Range basalt basement and overlying marginal basin strata, which comprise most of the rocks of the Uncas quadrangle. The Eocene submarine and subaerial tholeiitic basalt of the Crescent Formation on the Olympic Peninsula is thought to be the exposed mafic basement of the Coast Range, which was considered by Snavely and others (1968) to be an oceanic terrane accreted to the margin in Eocene time. In this interpretation, the Coast Range basalt terrane may have originated as an oceanic plateau or by oblique marginal rifting, but its subsequent emplacement history was complex (Wells and others, 1984). Babcock and others (1992) and Haeussler and others (2003) favor the interpretation that the basalts were the product of an oceanic spreading center interacting with the continental margin. Regardless of their origin, onlapping strata in southern Oregon indicate that the Coast Range basalts were attached to North America by 50 Ma; but on southern Vancouver Island, where the terrane-bounding Leech River Fault is exposed, Brandon and Vance (1992) concluded that suturing to North America occurred in the broad interval between 42 and 24 Ma. After emplacement of the Coast Range basalt terrane, the Cascadia accretionary wedge developed by frontal accretion and underplating (Tabor and Cady, 1978b; Clowes and others, 1987). Domal uplift of the part of the accretionary complex beneath the Olympic Mountains occurred after ~18 Ma (Brandon and others, 1998). Continental and alpine glaciation during Quaternary time reshaped the uplifted rocks of the Olympic Mountains.

Washington↗
USGS2015

National assessment of shoreline change: historical change along the north coast of Alaska, U.S.-Canadian border to Icy Cape

Beach erosion is a persistent problem along most open-ocean shores of the United States. Along the Arctic coast of Alaska, coastal erosion is widespread, may be accelerating, and is threatening defense and energy-related infrastructure, coastal habitats, and Native communities. As coastal populations continue to expand and infrastructure and habitat are increasingly threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There also is a need for a comprehensive analysis of shoreline change with metrics that are consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along the open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline change so that periodic, systematic, and internally consistent updates regarding coastal erosion and land loss can be made nationally. This report on shoreline change along the north coast of Alaska, between the U.S.-Canadian border and Icy Cape, is one in a series of regionally focused reports on historical shoreline change. Previous investigations include analyses and descriptive reports for the coasts of the U.S. Gulf of Mexico, the Southeast Atlantic, California, the New England and Mid-Atlantic, portions of Hawaii, and the Pacific Northwest coasts of Oregon and Washington. Similar to the earlier reports in this series, this report summarizes the methods of analysis, documents and describes the results of the analysis, and explains historical trends and rates of shoreline change. This Alaska shoreline change assessment differs from previously published shoreline change assessments in that: (1) only two historical shorelines (from the 1940s and 2000s eras) were available for the Alaska study area whereas four or more shorelines (from 1850 to 2002) were available for the other assessments and, thus, only end-point rates for one long-term analysis period are reported here, compared to a combination of long-term and short-term rates as reported in other studies; (2) modern (2000s era) shorelines in this study represent a visually derived land-water interface position versus an elevation based, tidally referenced shoreline position; and (3) both exposed open-ocean and sheltered mainland-lagoon shorelines and rates of change are included in this study compared to other locations where only exposed open-ocean sandy shorelines or bluff edges were evaluated. No distinction was made between sand or gravel beaches, and the base of the unconsolidated coastal bluff was considered the shoreline where no fronting beach existed.

Alaska↗
USGS2011

National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the New England and Mid-Atlantic coasts was -0.5 meters per year with an uncertainty in the long-term trend of plus or minus 0.09 meters per year. The rate is based on shoreline change rates averaged from 21,184 individual transects, of which 68 percent were eroding. In both the long and short term, the average rates of shoreline change for New England and the Mid-Atlantic were erosional. Long-term erosion rates were generally lower in New England than in the Mid-Atlantic. This is a function of the dominant coastal geomorphology; New England has a greater percentage of shore types that tend to erode more slowly (rocky coasts, pocket beaches, and mainland beaches), whereas the Mid-Atlantic is dominated by more vulnerable barrier islands and dynamic spit/inlet environments. However, the percentage of coastline eroding was higher in New England than in the Mid-Atlantic, highlighting that although rates of shoreline erosion may not be extreme, coastal erosion is still widespread along this region of the U.S. coastline. The average rate of short-term shoreline change for the New England and Mid-Atlantic coasts was also erosional but the rate of erosion decreased in comparison to long-term rates. The net short-term rate as averaged along 17,045 transects was -0.3 meters per year. Uncertainties for these rates range from 0.06 to 0.1 meters per year depending on the data sources used in the rate calculations. Of transects used to measure short-term change, 60 percent were erosional, as compared to 65 percent of coast eroding in the long term. The slight decrease (5 percent) in the amount of coastline eroding may be related to an increase in the frequency and extent of nourishment programs and (or) the effects of hardened structures during the more recent time period. The most stable (lower rates of erosion) beaches were more commonly found in New England. Despite an overall lowering of the average rates of erosion from long-term to short-term, the amount

Open-File Report↗
USGS2012

The emplacement of ophiolites by collision

Ophiolites, recognized in most of the world's orogenic belts, are generally interpreted to be oceanic crust and upper mantle (lithosphere) fragments that have been incorporated into continental margins at consuming plate boundaries. We suggest that the mechanism for ophiolite emplacement is the same in both the Alpine and Andean-type orogenes. In both geological settings, obduction of oceanic lithosphere onto the continental lithosphere is caused by the convergence of light, buoyant bodies such as oceanic plateaus, continental slivers, island arcs, or old hot spot traces. For example, the Troodos ophiolite complex, previously interpreted by some workers as resulting from continental collision, may have been emplaced by the collision of Cyprus with the Eratosthenes Plateau embedded in the oceanic eastern Mediterranean crust. On the other hand, the Upper Jurassic Coast Range Ophiolites of California, previously interpreted as resulting from typical oceanic subduction, may be the result of a continuous injection of thick nonsubductable packages of light, continentally derived sedimentary rocks, seamounts, and plateaus into the subduction zones. Many other ophiolite complexes may be similarly related to accreted terranes.

Journal of Geophysical Research↗
USGS2012

Studying ocean acidification in the Arctic Ocean

The U.S. Geological Survey (USGS) partnership with the U.S. Coast Guard Ice Breaker Healey and its United Nations Convention Law of the Sea (UNCLOS) cruises has produced new synoptic data from samples collected in the Arctic Ocean and insights into the patterns and extent of ocean acidification. This framework of foundational geochemical information will help inform our understanding of potential risks to Arctic resources due to ocean acidification.

Fact Sheet↗
USGS1995

Late Pleistocene and Holocene paleoenvironments of the North Pacific coast

Unlike the North Atlantic, the North Pacific Ocean probably remained free of sea ice during the last glacial maximum (LGM), 22,000 to 17,000 BP. Following a eustatic low in sea level of ca. −120 m at 19,000 BP, a marine transgression had flooded the Bering and Chukchi shelves by 10,000 BP. Post-glacial sea-level history varied widely in other parts of the North Pacific coastline according to the magnitude and timing of local tectonism and glacio-isostatic rebound. Glaciers covered much of the continental shelf between the Alaska Peninsula and British Columbia during the LGM. Maximum glacier extent during the LGM was out of phase between southern Alaska and southern British Columbia with northern glaciers reaching their outer limits earlier, between 23,000 and 16,000 BP, compared to 15,000–14,000 BP in the south. Glacier retreat was also time-transgressive, with glaciers retreating from the continental shelf of southern Alaska before 16,000 BP but not until 14,000–13,000 BP in southwestern British Columbia. Major climatic transitions occurred in the North Pacific at 24,000–22,000, 15,000–13,000 and 11,000–9000 BP. Rapid climate changes occurred within these intervals, including a possible Younger Dryas episode. An interval of climate warmer and drier than today occurred in the early Holocene. Cooler and wetter conditions accompanied widespread Neoglaciation, beginning in some mountain ranges as early as the middle Holocene, but reaching full development after 3000 BP.

Quaternary Science Reviews↗
USGS2003

Life and death of the resurrection plate: Evidence for its existence and subduction in the northeastern Pacific in Paleocene-Eocene time

Onshore evidence suggests that a plate is missing from published reconstructions of the northeastern Pacific Ooean in Paleocene- Eocene time. The Resurrection plate, named for the Resurrection Peninsula ophiolite near Seward, Alaska, was located east of the Kula plate and north of the Farallon plate. We interpret coeval near-trench magmatism in southern Alaska and the Cascadia margin as evidence for two slab windows associated with trench-ridge-trench (TRT) triple junctions, which formed the western and southern boundaries of the Resurrection plate. In Alaska, the Sanak-Baranof belt of near-trench intrusions records a west-to-east migration, from 61 to 50 Ma, of the northern TRT triple junction along a 2100-km-long section of coastline. In Oregon, Washington, and southern Vancouver Island, voluminous basaltic volcanism of the Siletz River Volcanics, Crescent Formation, and Metchosin Volcanics occurred between ca. 66 and 48 Ma. Lack of a clear age progression of magmatism along the Cascadia margin suggests that this southern triple junction did not migrate significantly. Synchronous near-trench magmatism from southeastern Alaska to Puget Sound at ca. 50 Ma documents the middle Eocene subduction of a spreading center, the crest of which was subparallel to the margin. We interpret this ca. 50 Ma event as recording the subduction-zone consumption of the last of the Resurrection plate. The existence and subsequent subduction of the Resurrection plate explains (1) northward terrane transport along the southeastern Alaska-British Columbia margin between 70 and 50 Ma, synchronous with an eastward-migrating triple junction in southern Alaska; (2) rapid uplift and voluminous magmatism in the Coast Mountains of British Columbia prior to 50 Ma related to subduction of buoyant, young oceanic crust of the Resurrection plate; (3) cessation of Coast Mountains magmatism at ca. 50 Ma due to cessation of subduction, (4) primitive mafic magmatism in the Coast Mountains and Cascade Range just after 50 Ma, related to slab-window magmatism, (5) birth of the Queen Charlotte transform margin at ca. 50 Ma, (6) extensional exhumation of high-grade metamorphic terranes and development of core complexes in British Columbia, Idaho, and Washington, and extensional collapse of the Cordilleran foreland fold-and-thrust belt in Alberta, Montana, and Idaho after 50 Ma related to initiation of the transform margin, (7) enigmatic 53-45 Ma magmatism associated with extension from Montana to the Yukon Territory as related to slab breakup and the formation of a slab window, (8) right-lateral margin-parallel strike-slip faulting in southern and western Alaska during Late Cretaceous and Paleocene time, which cannot be explained by Farallon convergence vectors, and (9) simultaneous changes in Pacific-Farallon and Pacific-Kula plate motions concurrent with demise of the Kula-Resurrection Ridge.

Geological Society of America Bulletin↗
USGS2013

Fish: Section 4.8 in Climate change and the Olympic Coast National Marine Sanctuary: Interpreting potential futures.

Summary Decreased ocean survival of Chinook and coho salmon in the coastal waters of Washington, Oregon, and California is likely based on historical and present day observations during conditions of unusually high water temperatures and reduced or delayed upwelling. Based on observations during conditions of unusually high water temperatures and reduced or delayed upwelling, highly migratory southern species including Pacific hake, jack and Pacific chub mackerel, and Pacific sardine will likely become more abundant and distributed closer to shore off Washington. In contrast, resident forage fish including northern anchovy, Pacific herring, and smelts (surf and whitebait) may become less abundant. Small pelagic fish (i.e. forage fish and mackerel) respond more rapidly to climaterelated changes in ocean conditions than benthic fish. Distribution and abundance of benthic fish reflect average ocean conditions over periods of many years. A key question for groundfish is how long term, sustained changes in ocean conditions will affect the current spatial configuration of habitats and fish communities, and the productivity of those habitats and communities. Little is known about effects of ocean acidification on northeast Pacific fish; however, work with tropical reef fish suggests that increased acidity impairs larval fish behavior (their ability to find suitable reef habitat from olfactory and auditory cues) and ultimately their survival. Response of benthic fish in the OCNMS to future increases in hypoxia will likely be similar to those for fish off the central Oregon coast where hypoxia developed each summer starting in 2002. Abundance and condition of fish will decline in hypoxic areas. Fish will move inshore seeking higher oxygen concentrations. Species adapted to low oxygen environments, for example Dover sole, will be less affected.

California, Oregon, Washington↗
USGS2013

Understanding processes controlling sediment transports at the mouth of a highly energetic inlet system (San Francisco Bay, CA)

San Francisco Bay is one of the largest estuaries along the U.S. West Coast and is linked to the Pacific Ocean through the Golden Gate, a 100 m deep bedrock inlet. A coupled wave, flow and sediment transport model is used to quantify the sediment linkages between San Francisco Bay, the Golden Gate, and the adjacent open coast. Flow and sediment transport processes are investigated using an ensemble average of 24 climatologically derived wave cases and a 24.8 h representative tidal cycle. The model simulations show that within the inlet, flow and sediment transport is tidally dominated and driven by asymmetry of the ebb and flood tides. Peak ebb velocities exceed the peak flood velocities in the narrow Golden Gate channel as a result of flow convergence and acceleration. Persistent flow and sediment gyres at the headland tips are formed that limit sediment transfer from the ebb-tidal delta to the inlet and into the bay. The residual transport pattern in the inlet is dominated by a lateral segregation with a large ebb-dominant sediment transport (and flow) prevailing along the deeper north side of the Golden Gate channel, and smaller flood dominant transports along the shallow southern margin. The seaward edge of the ebb-tidal delta largely corresponds to the seaward extent of strong tidal flows. On the ebb-tidal delta, both waves and tidal forcing govern flow and sediment transport. Wave focusing by the ebb-tidal delta leads to strong patterns of sediment convergence and divergence along the adjacent Ocean Beach.

California↗