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At least 721 records · Page 40Linked to original sources
USGS2014

Historical and contemporary imagery to assess ecosystem change on the Arctic coastal plain of northern Alaska

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low-relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades leading to thawing of on-shore permafrost and the disappearance of sea ice at unprecedented rates. The U.S. Geological Survey’s (USGS) Changing Arctic Ecosystems (CAE) research initiative was developed to investigate and forecast these rapid changes in the physical environment of the Arctic, and the associated changes to wildlife populations, in order to inform key management decisions by the U.S. Department of the Interior and other agencies. Forecasting future wildlife responses to changes in the Arctic can benefit greatly from historical records that inform what changes have already occurred. Several Arctic wildlife and plant species have already responded to climatic and physical changes to the Arctic Coastal Plain of northern Alaska. Thus, we located historical aerial imagery to improve our understanding of recent habitat changes and the associated response to such changes by wildlife populations. In this report, we describe and make available a set of 61 georectified aerial images of the Arctic Coastal Plain (taken from 1948 to 2010) that were obtained by the USGS to inform research objectives of the USGS CAE Initiative. Here, we describe the origins, metadata, and public availability of these images that were obtained within four main study areas on the Arctic Coastal Plain: Teshekpuk Lake Special Area, Chipp River, the Colville River Delta, and locations along the Dalton Highway Corridor between the Brooks Range and Deadhorse. We also provide general descriptions of observable changes to the geomorphology of landscapes that are apparent by comparing historical and contemporary images. These landscape changes include altered river corridors, lake drying, coastal erosion, and new vegetation communities. All original and georectified images and metadata are available through the USGS Alaska Science Center Portal (search under ‘Project Name’ using title of this report) or by contacting ascweb@usgs.gov .

Alaska↗
USGS2015

Monitoring population status of sea otters ( Enhydra lutris ) in Glacier Bay National Park and Preserve, Alaska: options and considerations

After many decades of absence from southeast Alaska, sea otters ( Enhydra lutris ) are recolonizing parts of their former range, including Glacier Bay, Alaska. Sea otters are well known for structuring nearshore ecosystems and causing community-level changes such as increases in kelp abundance and changes in the size and number of other consumers. Monitoring population status of sea otters in Glacier Bay will help park researchers and managers understand and interpret sea otter-induced ecosystem changes relative to other sources of variation, including potential human-induced impacts such as ocean acidification, vessel disturbance, and oil spills. This report was prepared for the National Park Service (NPS), Southeast Alaska Inventory and Monitoring Network following a request for evaluation of options for monitoring sea otter population status in Glacier Bay National Park and Preserve. To meet this request, we provide a detailed consideration of the primary method of assessment of abundance and distribution, aerial surveys, including analyses of power to detect interannual trends and designs to reduce variation around annual abundance estimates. We also describe two alternate techniques for evaluating sea otter population status—(1) quantifying sea otter diets and energy intake rates, and (2) detecting change in ages at death. In addition, we provide a brief section on directed research to identify studies that would further our understanding of sea otter population dynamics and effects on the Glacier Bay ecosystem, and provide context for interpreting results of monitoring activities.

Alaska↗
USGS2019

Measurement of long-term channel change through repeated cross-section surveys at bridge crossings in Alaska

The U.S. Geological Survey (USGS) has been working with Alaska Department of Transportation and Public Facilities (ADOT&PF) since 1993 to provide hydraulic assessments of scour for bridges throughout Alaska. The purpose of the program is to evaluate, monitor, and study streambed scour at bridges in Alaska; this includes surveying streambed elevations at regular intervals and monitoring real-time bed elevation changes. Over the duration of the scour program (1994–2017), repeated cross sections have been surveyed along the lengths of 76 bridges. Channel soundings are depth-from-bridge measurements on either the upstream or downstream side of a bridge. Flow, depth, and velocity dictated whether streambed elevations were measured using either USGS sounding weights on cable reels, weighted measuring tapes, or acoustic Doppler current profilers. The soundings were done on an annual basis at most sites. In addition to annual soundings, channel soundings were made during floods or periods of scour. Results show that general scour can be uniform or non-uniform across the channel. The magnitude and distribution of scour across the channel are influenced by several factors that include streambed sediment type, degree of channel contraction at the bridge crossing, influence of instream structures, and bridge pier location and alignment. The data collected from the repeat soundings can be used to identify long-term aggradation or degradation of the streambed, as well as seasonal changes in streambed elevations.

Alaska↗
USGS2022

Abundance and distribution of eelgrass (Zostera marina) and seaweeds at Izembek National Wildlife Refuge, Alaska, 2007–10

Eelgrass ( Zostera marina ) meadows are expansive along the lower Alaska Peninsula, supporting a rich diversity of marine life, yet little is known about their status and trends in the region. We tested techniques to inventory and monitor trends in the spatial extent and abundance of eelgrass in lagoons of the Izembek National Wildlife Refuge. We determined if Landsat imagery could be used to assess eelgrass spatial extent in shallow (less than 4 meter water depth) coastal waters of the refuge. We determined that this seagrass could be differentiated using Landsat imagery from other cover types (that is, channels and unvegetated tidal flats) with a high degree of accuracy (greater than 80 percent) in Izembek and Kinzarof Lagoons. Eelgrass meadows represented the largest cover type in Izembek (about 16,000 hectares) and Kinzarof (about 900 hectares) Lagoons, comprising between 45 and 50 percent of the spatial extent of these lagoons, respectively. When compared to estimates of spatial extent of eelgrass from previous studies, our results suggest little change in the spatial extent of eelgrass in Izembek Lagoon during the 28-year period 1978 through 2006. Preliminary mapping of eelgrass in other embayments indicated that this seagrass was also expansive in Big Lagoon (about 900 hectares; or 34 percent of the lagoon area) and Hook Bay (about 900 hectares; or 36 percent of the bay area) but not in Cold Bay (about 100 hectares; less than 5 percent of the bay area). We conducted an embayment-wide point sampling technique to assess aboveground biomass and distribution of eelgrass and seaweeds and presence of six macro-invertebrates during a 4-year period (2007–10). We determined that, when present, mean aboveground biomass of eelgrass was greater in Kinzarof Lagoon (182.5 plus or minus 12.1 grams dry weight per square meter) than in Izembek Lagoon (152.1 plus or minus 7.1 grams dry weight per square meter) in 2008–10, possibly reflecting the warmer sea temperatures and higher salinities found on the Gulf of Alaska side of the Alaska Peninsula. Seaweeds were more abundant in Kinzarof Lagoon than in Izembek Lagoon, surpassing aboveground biomass of eelgrass in both lagoons in 2008. Gastropods (4 percent of all points) and Caprella shrimp (25 percent) were the most common of the six macro-invertebrates surveyed in Izembek Lagoon, and Telmessus crab was the most common macro-invertebrate in Kinzarof Lagoon.

Alaska↗
USGS2021

Red-throated loon (Gavia stellata) use of nearshore marine habitats—Results from a 2019 pilot study in northern Alaska

Red-throated loons ( Gavia stellata ) are a species of conservation concern in Alaska due to recent evidence of a population decline on the Arctic Coastal Plain (ACP) in northern Alaska. In 2019, the U.S. Geological Survey and the U.S. Fish and Wildlife Service conducted a pilot study to evaluate diet and use of nearshore foraging areas as possible drivers of the population decline. We collected fat biopsies to examine diet of breeding red-throated loons using previously outlined methods. We also deployed GPS-Ultra High Frequency transmitters on red-throated loons for an initial understanding of detailed offshore marine habitat use during the breeding season. A broader research project on marine habitat use and fish diet of breeding red-throated loons will begin in 2021 on the Canning River Delta and in Foggy Island Bay, Alaska.

Alaska↗
USGS2022

Inventory of eelgrass (Zostera marina) and seaweeds at the end of the Alaska Peninsula, August–September 2012:

Coastal communities in Alaska are undergoing rapid environmental change from increasing temperatures and baseline data are needed to monitor potential impacts. We conducted the first surveys of the abundance and distribution of eelgrass ( Zostera marina ) and seaweeds in the western part of Izembek National Wildlife Refuge at the end of the Alaska Peninsula. Six embayments and two offshore islands were surveyed in August–September of 2012. Biotic (percent cover of eelgrass/seaweeds, presence/absences of five sessile invertebrates), and abiotic (water temperature, salinity, and depth) data were recorded at 257 survey points (range =9–74 points per site) across all sites. Twenty-two genera/species of seaweeds were identified at the six embayments. New seaweed species for the offshore islands of Sanak and Caton were added to an existing seaweed collection accessioned at the University of British Columbia Herbarium. We also collected samples of eelgrass to be accessioned at U.S. Geological Survey, Alaska Science Center-Molecular Ecology Laboratory, for future genetic analyses. Fifty-three species of birds and 13 species of mammals were observed and recorded during the survey period.

Alaska↗
USGS2021

Preliminary assessment of the wave generating potential from landslides at Barry Arm, Prince William Sound, Alaska

We simulated the concurrent rapid motion of landslides on an unstable slope at Barry Arm, Alaska. Movement of landslides into the adjacent fjord displaced fjord water and generated a tsunami, which propagated out of Barry Arm. Rather than assuming an initial sea surface height, velocity, and location for the tsunami, we generated the tsunami directly using a model capable of simulating the dynamics of both water and landslide material. The fjord below most of the landslide source area was occupied by the Barry Glacier until about 2012; therefore, our direct simulation of tsunami generation by landslide motion required new topographic and bathymetric data, which was collected in 2020. The topographic data also constrained landslide geometries and volumes. We considered four scenarios based on two landslide volumes and two landslide mobilities—a more mobile, contractive landslide and a less mobile, noncontractive landslide. The larger of the two volumes is 689 × 10 6 cubic meters (m 3 )—larger than the volume estimate in a previous study—and reflects the largest plausible volume given current observational data. The considered scenario that generated the largest wave heights resulted in forecast wave heights of over 200 meters (m) in the northern part of Barry Arm, adjacent to the landslide source area and runup on the opposite fjord wall in excess of 500 m. Simulated wave heights in excess of 5 m in southern Barry Arm and in Harriman Fjord occurred within 10–15 minutes (min) of landslide motion. The simulated tsunami reached Whittier, Alaska, approximately 20 min after initial rapid landslide motion, with peak heights of just over 2 m in Passage Fjord, 500 m offshore Whittier, occurring 26 min after initial rapid motion. Time of peak wave heights was consistent with previous modeling. Although results are preliminary and can be refined with additional observations and analyses, they provide a refined assessment of the upper bound of the hazard presented by the Barry Arm landslides. The results herein support the National Oceanic and Atmospheric Administration’s National Tsunami Warning Center mission to detect, forecast, and warn for tsunamis in Alaska.

Alaska↗
USGS1960

Ground-water data for Fairbanks area, Alaska

A compilation of records of about 450 wells in the Fairbanks area is presented herein. The data were collected by D. J. Cedarstrom and Troy L. Pewe during the first phases of an investigation by the United States Geological Survey of the permafrost, terrain, and water resources of the Fairbanks area. The enclosed map of the area, showing well locations, was prepared by the Regional Sanitary Engineer, Sanitation and Engineering, Alaska Department of Health and Welfare. The data were released to the Survey's open file in 1948, but are reproduced in the Alaska Department of Health and Welfare Hydrological Data series to insure preservation. Where known, the data include for each well the names of the owner and driller; the depth of the well; the depth to the top and bottom of permafrost; and the reported quality of water. The well records and location may be very useful for future subsurface investigations or construction. The well location map was based on the Fairbanks street names as of 1948. Since that time, many of the street names and the numbering system have changed. Hence, the reader should not refer to the address of a particular well, but to the well number when locating a well on the map. The Geological Survey has recompiled the well data in the Fairbanks area for its final phase of a ground-water study. Data through 1954 is to be presented in a Water-Supply Paper now in preparation. Pertinent portions of the enclosed well data will be presented in the forthcoming report. Some of the enclosed well data, and additional well logs, have been published in a report (Pewe, Troy L., 1958, Geology of the Fairbanks (D-2) quadrangle, Alaska: U. S. Geological Survey GQ 110) describing the geology and subsurface conditions in the area.

Alaska↗
USGS1956

Engineering geology of the Nenana-Rex area, Alaska

A geological examination of the Nenana-Rex area, Alaska, was made during August, 1954 by a Geological Survey party consisting of Reuben Kachadoorian, geologist, and Lloyd Plafker, field assistant. The area examined lies in parts of the Fairbanks A-4, A-5, B-4, B-5, C-4 and C-5 quadrangles (fig. 1). A preliminary highway route and the Alaska Railroad cross the area mapped. The preliminary highway route, surveyed in the summer of by the Alaska Road Commission, is a segment of a proposed road from Fairbanks to McKinley Park (pl. 1). The area was mapped with special emphasis placed upon geologic factors that would affect construction of the new highway. This report is a result of the studies along the highway and railroad routes, and describes only those areas that are of immediate importance in planning and construction of the highway (pl. 1).

Alaska↗
USGS1960

The physiographic provinces of Alaska

The wealth of recently accumulated geographic information on Alaska has made desirable a new classification of the state into physiographic divisions. Most of Alaska is now covered by topographic maps of high quality at scales of 1:63,360 and 1:250,000, prepared by multiplex methods from aerial photography. A classification made now is not likely to err through lack of knowledge of the geography and topography of the state; any changes it requires will reflect matters of judgment and taste, rather than ignorance. The accompanying classification was prepared intermittently between 1949 and 1959; most of the work was done between 1956 and 1959. It is hoped that it will bring about a clearer understanding of the geography of Alaska and will stimulate research into the history of development of Alaskan landforms.

Alaska↗
USGS1968

Platinum deposits of Alaska

The placer deposits of the Goodnews Bay district in southwestern Alaska have yielded the only significant production of platinum metals in the United States, although small amounts of platinum metals have been produced from other deposits in Alaska and elsewhere in the United States. The Goodnews Bay deposits were described by Mertie in U.S. Geological Survey Bulletin 918 (1940). Many new data have been obtained since that time, and in order to make this information available in advance of publication, this report on Platinum deposits of Alaska has been placed on open-file.

Alaska↗
USGS1971

Cretaceous plutonic rocks of St. Lawrence Island, Alaska; a preliminary report

Reconnaissance mapping on St. Lawrence Island, Alaska has revealed seven epizonal granitic plutons of mid-Cretaceous age with a combined outcrop area of about 350 square miles. The plutonic rocks are dominantly quartz monzonite, but include minor amounts of granodiorite, monzonite, syenite, syenodiorite, and alaskite. The plutons are structurally and petrologically similar to and about the same age as plutons on the Chukotsky Peninsula, U.S.S.R. and in western Alaska. They suggest tectonic continuity between Siberia and Alaska since at least Cretaceous time. Several mineralized areas containing molybdenum, copper, lead, and zinc sulfides are associated with the plutonic bodies in the western part of the island.

Alaska↗
USGS1974

Geological Survey published reports on Alaska, 1915-1939, indexed by quadrangle

Geological Survey reports published as Professional Papers, Bulletins, Water Supply Papers, and Circulars are listed by the quadrangles (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 3). This index does not include reports that deal only with administrative matters or that were placed in open files but not formally published. Reports that deal with Alaska as a whole, with areas that can not be identified with any specific quadrangle, or with offshore areas that are not within quadrangle boundaries, or that consist mainly of statistical data on the quality or quantity of water are listed under ALASKAGENERAL, as are bibliographies, indexes, and similar publications. The ALASKA - GENERAL list appears before the alphabetically arranged quadrangle listings.

Alaska↗
USGS1974

Geological Survey published reports on Alaska, 1884-1914, indexed by quadrangle

Geological Survey reports published as Annual Reports, Monographs, Special Reports, Professional Papers, Bulletins, and Water Supply Papers are listed by the quadrangles (scale 1:250,000) into which Alaska has been divided for topographic mapping (p. 2). This index does not include any reports that deal solely with administrative matters. Reports that deal with Alaska as a whole or with areas that can not be identified with any specific quadrangle are listed under ALASKA - GENERAL, as are bibliographies, indexes, and similar publications. The ALASKAGENERAL list appears before the alphabetically arranged quadrangle listings.

Alaska↗
USGS1975

Preliminary report on the reconnaissance engineering geology of the Yakutat area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards

Yakutat, situated about 225 miles northwest of Juneau, Alaska, near the shores of the Gulf of Alaska, has a setting that calls for superlatives. Within the Yakutat region are some of the tallest mountains, some of the heaviest snowfalls, and the largest glacier in North America. Between the abrupt mountain front and the Gulf of Alaska lies a very gently sloping plain of outwash derived from repeated cycles of advance followed by melt and retreat of glaciers during the Quaternary Period. The latest melting probably took place 500 to 600 years ago. Yakutat is built upon the moderately steep moraine that is the product of melting of one of these glaciers. Near Yakutat, surficial deposits are as much as 700 feet thick and probably overlie siltstone, sandstone, and mudstone. The eight general categories of mapped surficial deposits include artificial fill, organic, eolian, beach, delta-estuarine, alluvial, and outwash deposits, and deposits of the outer Yakutat Bay moraine complex.

Alaska↗
USGS1975

Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Teller Quadrangle, Alaska

This summary of references is designed to aid in library research on metallic and nonmetallic (other than mineral fuels and construction materials) mineral occurrences in the Teller quadrangle, Alaska. All references to published and open-filed reports of the Geological Survey, to most published and open-filed reports of the U.S. Bureau of Mines, and to most published reports of the State of Alaska Division of Geological and Geophysical Surveys and its predecessor State and Territorial agencies released before January 1, 1975, are summarized. Certain, mainly statistical, reports such as the annual Minerals Yearbook of the U.S. Bureau of Mines and the biennial and annual reports of the State of Alaska Division of Gedlogical and Geophysical Surveys and its predecessor State and Territorial agencies are not included. This summary is divided into three parts: a section made up of summaries of references arranged alphabetically by occurrence name; a section that lists synonyms for names in the first section, claim names, and the names of operators and owners of mines and prospects; and a section that lists, by author, all references summarized in the first section and cited in introductory paragraphs. Pages are not numbered because users may wish to add data from other sources.

Alaska↗
USGS1975

Summary of references to mineral occurrences (other than mineral fuels and construction materials) in five quadrangles in West-Central Alaska (Hughes, Kotzebue, Melozitna, Selawik, Shungnak)

These summaries of references are designed to aid in library research on metallic and nonmetallic (other than mineral fuels and construction materials) mineral occurrences in 5 quadrangles in west-central Alaska. All references to published and open-filed reports of the Geological Survey, to most published and open-filed reports of the U.S. Bureau of Mines, and to most published reports of the State of Alaska Division of Geological and Geophysical Surveys and its predecessor State and Territorial agencies released before January 1, 1975, are summarized. Occasionally reports from other sources have been included; in such instances references have been summarized in greater detail than those to the kinds of reports listed above. Certain, mainly statistical, reports such as the annual Minerals Yearbook of the U.S. Bureau of Mines and the biennial and annual reports of the State of Alaska Division of Geological and Geophysical Surveys and its predecessor State and Territorial agencies are not included. This report is divided into three parts: a section made up of summaries of references arranged alphabetically first by quadrangle and second by occurrence name; a section that lists synonyms for names in the first section, claim names, and the names of operators and owners of mines and prospects; and a section that lists, by author, all references summarized in the first section.

Alaska↗
USGS1975

Summary of references to mineral occurrences (other than mineral fuels and construction materials) in Northern Alaska

These summaries of references are designed to aid in library research on metallic and nonmetallic (other than mineral fuels and construction materials) mineral occurrences in 11 quadrangles in northern Alaska. All references to published and open-filed reports of the Geological Survey, to most published and open-filed reports of the U.S. Bureau of Mines, and to most published reports of the State of Alaska Division of Geological and Geophysical Surveys and its predecessor State and Territorial agencies released before January 1, 1975. are summarized. Occasionally reports from other sources have been included; in such instances references have been summarized in greater detail than those to the kinds of reports listed above. Certain, mainly statistical reports such as the annual Minerals Yearbook of the U.S. Bureau of Mines and the biennial and annual reports of the State of Alaska Division of Geological and Geophysical Surveys and its predecessor State and Territorial agencies are not included. This report is divided into three parts: a section made up of summaries of references arranged alphabetically first by quadrangle and second by occurrence name; a section that lists synonyms for names in the first section, claim names, and the names of operators and owners of mines and prospects; and a section that lists, by author, all references summarized in the first section.

Alaska↗