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

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At least 937 records · Page 52Linked to original sources
USGS1920

Pliocene and Pleistocene fossils from the Arctic coast of Alaska and the auriferous beaches of Nome, Norton Sound, Alaska

Exploration of the geology of the Arctic and subarctic shores of Alaska began as early as the voyages of Kotzebue and Beechey, in 1816 and 1826, and a detailed report on the vertebrate fossils found there, with a wealth of illustration, was made by Sir John Richardson in 1854, in the "Zoology of the voyage of the Herald." Nothing of importance beating on the Tertiary invertebrates of this region appears in the literature of the nineteenth century, and but little on those of the older formations.

Alaska↗
USGS1904

A reconnaissance in northern Alaska across the Rocky Mountains, along Koyukuk, John, Anaktuvuk, and Colville Rivers, and the Arctic coast to Cape Lisburne, in 1901, with notes

Since 1898 the United States Geological Survey has been carrying on systematic topographic and geologic surveys in Alaska under an appropriation made for the investigation of the mineral resources of the Territory. This work has included not only areal surveys of regions already being developed by the miner and prospector, but also explorations and investigations of regions that are little known or entirely unexplored. As a result of these explorations a network of reconnaissance traverses has been extended over a large part of Alaska, where route surveys of this character must necessarily precede more detailed topographic and geologic mapping. They serve to outline the main geographic features of the country and afford the pioneer or prospector a guide for his journeys as well as help him to select his field of operations. The present report and maps are the results of such an investigation.

Alaska↗
USGS1963

Effects of drought along Pacific Coast in California: Chapter G in Drought in the Southwest, 1942-56

The drought 1945-56 in California affected principally the southern part of the State, and was one of a series that has been recorded in the past century. Although the precipitation in any individual year is not predictable, the pattern of alternating wetter and drier periods is consistent enough that there is clearly a- need for storing the surpluses of wetter periods to provide adequate water supplies in dry years. This cyclic storage is a basic element in the California water plan. Wherever the storage increments in wet years provide adequate supplies throughout the periods of precipitation deficiency, the effect of drought upon mankind has been overcome, or at least minimized. However, whenever the deficiency is greater than has been experienced in past droughts, some downward revisions may be necessary in previous estimates of the firm supply available for man's use.

California↗
USGS2018

Framework geologic map and structure sections along the Bartlett Springs fault zone and adjacent area from Round Valley to Wilbur Springs, northern Coast Ranges, California

The geologic map and accompanying report describes the extent, complexity, architecture, and evolution of the Bartlett Springs Fault Zone between Clear Lake and Round Valley, California. This fault zone is the eastern-most known active member of the San Andreas transform margin in northern California. It is of particular interest for its apparent long-lived history as a Miocene and older subduction-margin fault that, more recently, was reactivated as an active, creeping member of the San Andreas Fault system. The northern part of the Bartlett Springs Fault Zone is apparently still influenced by subduction of the Gorda Plate beneath North America, but it also accommodates strike-slip displacement associated with interaction of the Pacific Plate with North America. South of the map area, the Bartlett Springs Fault Zone steps into and merges with active faults of the eastern San Francisco Bay region; to the north of the map area and Round Valley, the fault zone steps into several other fault zones that connect with offshore thrust faults of the Cascadia subduction margin. Adequate understanding of the geologic framework of this fault zone and its relation to crustal structure of the adjacent region is important for purposes of planning and upgrading hydro-electric and other infrastructure in northern California that is directly or indirectly impacted by active faulting.

California↗
USGS2008

Submarine ground-water discharge and fate along the coast of Kaloko-Honokohau National Historical Park, Island of Hawai'i: Part 2, spatial and temporal variations in salinity, radium-isotope activity, and nutrient concentrations in coastal waters, December 2003 - April 2006

The aquatic resources of Kaloko-Honokohau National Historical Park, including rocky shoreline, fishponds, and anchialine pools, provide habitat to numerous plant and animal species and offer recreational opportunities to local residents and tourists. A considerable amount of submarine groundwater discharge was known to occur in the park, and this discharge was suspected to influence the park's water quality. Thus, the goal of this study was to characterize spatial and temporal variations in the quality and quantity of groundwater discharge in the park. Samples were collected in December 2003, November 2005, and April 2006 from the coastal ocean, beach pits, three park observation wells, anchialine pools, fishponds, and Honokohau Harbor. The activities of two Ra isotopes commonly used as natural ground-water tracers (223Ra and 224Ra), salinity, and nutrient concentrations were measured. Fresh ground water composed a significant proportion (8-47 volume percent) of coastal-ocean water. This percentage varied widely between study sites, indicating significant spatial variation in submarine groundwater discharge at small (meter to kilometer) scales. Nitrate + nitrite, phosphate, and silica concentrations were significantly higher in nearshore coastal-ocean samples relative to samples collected 1 km or more offshore, and linear regression showed that most of this difference was due to fresh ground-water discharge. High-Ra-isotope-activity, higher-salinity springs were a secondary source of nutrients, particularly phosphate, at Honokohau Harbor and Aiopio Fishtrap. Salinity, Ra-isotope activity, and nutrient concentrations appeared to vary in response to the daily tidal cycle, although little seasonal variation was observed, indicating that submarine ground-water discharge may buffer the park's water quality against the severe seasonal changes that would occur in a system where freshwater inputs were dominated by rivers and runoff. Ra-isotope-activity ratios indicated that the residence time of water in the coastal ocean at the study sites was less than 1.6 days. We calculated water and nutrient fluxes into the coastal ocean at each study site. This study provides a baseline description of submarine ground-water discharge in Kaloko-Honokohau National Historical Park and its effect on the park's aquatic resources. We hope that it will allow park managers to better assess potential future changes in ground-water quality and quantity and conserve the park's valuable resources.

Hawaii↗