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At least 307 records · Page 17Linked to original sources
USGS2007

Geologic Map of the MTM -30262 and -30267 Quadrangles, Hadriaca Patera Region of Mars

Introduction Mars Transverse Mercator (MTM) -30262 and -30267 quadrangles cover the summit region and east margin of Hadriaca Patera, one of the Martian volcanoes designated highland paterae. MTM -30262 quadrangle includes volcanic deposits from Hadriaca Patera and Tyrrhena Patera (summit northeast of map area) and floor deposits associated with the Dao and Niger Valles canyon systems (south of map area). MTM -30267 quadrangle is centered on the caldera of Hadriaca Patera. The highland paterae are among the oldest, central-vent volcanoes on Mars and exhibit evidence for explosive eruptions, which make a detailed study of their geology an important component in understanding the evolution of Martian volcanism. Photogeologic mapping at 1:500,000-scale from analysis of Viking Orbiter images complements volcanological studies of Hadriaca Patera, geologic investigations of the other highland paterae, and an analysis of the styles and evolution of volcanic activity east of Hellas Planitia in the ancient, cratered highlands of Mars. This photogeologic study is an extension of regional geologic mapping east of Hellas Planitia. The Martian highland paterae are low-relief, areally extensive volcanoes exhibiting central calderas and radial channels and ridges. Four of these volcanoes, Hadriaca, Tyrrhena, Amphitrites, and Peneus Paterae, are located in the ancient cratered terrains surrounding Hellas Planitia and are thought to be located on inferred impact basin rings or related fractures. Based on analyses of Mariner 9 images, Potter (1976), Peterson (1977), and King (1978) suggested that the highland paterae were shield volcanoes formed by eruptions of fluid lavas. Later studies noted morphologic similarities between the paterae and terrestrial ash shields and the lack of primary lava flow features on the flanks of the volcanoes. The degraded appearances of Hadriaca and Tyrrhena Paterae and the apparently easily eroded materials composing their low, broad shields further suggest that the highland paterae are composed predominantly of pyroclastic deposits. Analyses of eruption and flow processes indicate that the distribution of units at Hadriaca and Tyrrhena Paterae is consistent with emplacement by gravity-driven pyroclastic flows. Detailed geologic study of the summit caldera and flanks of Hadriaca Patera is essential to determine the types of volcanic materials exposed, the nature of the processes forming these deposits, and the role of volcanism in the evolution of the cratered highlands that are characteristic of the southern hemisphere of Mars.

Scientific Investigations Map↗
USGS1988

Volcanology in Hawaii

Polynesians who first inhabited the Hawaiian Islands told in legend about Pele, Goddess of volcanic fires, who migrated from the Island of Kauai to Oahu, then to Maui, and finally to her present home in Kilauea Volcano's Halemaumau Crater on the Island of Hawaii. Geologists today accept this same relative age progressions for the evolution of the islands, demonstrating the kernels of geologic truth may lie in long-lived myths and legends. J.D. Dana, a geologist with a United states exploring expedition in the 1840's, was the first to write about the increase in age of the Hawaiian Islands to the northwest. He noted that weathering of the lavas, erosional destruction of the islands by waves and streams and the growth of reeds around the islands progressively increased away from the Island of Hawaii. He correctly established the islands' relative ages, but absolute ages had to wait for over 120 years until radioactive age-dating techniques became available.

Hawaii↗
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↗
USGS2009

Status of Groundwater Levels and Storage Volume in the Equus Beds Aquifer Near Wichita, Kansas, January 2009

Beginning in the 1940s, the Wichita well field was developed in the Equus Beds aquifer in southwestern Harvey County and northwestern Sedgwick County to supply water to the city of Wichita (Williams and Lohman, 1949). In addition to supplying drinking water to the largest city in Kansas, the other primary use of water from the Equus Beds aquifer is to irrigate crops in this agriculture-dominated part of south-central Kansas (Rich Eubank, Kansas Department of Agriculture, Division of Water Resources, oral commun., 2008). The decline of water levels in the aquifer were noted soon after the development of the Wichita well field began (Williams and Lohman, 1949). As water levels in the aquifer decline, the volume of water stored in the aquifer decreases and less water is available to supply future needs. For many years the U.S. Geological Survey (USGS), in cooperation with the city of Wichita, has monitored these changes in water levels and the resulting changes in storage volume in the Equus Beds aquifer as part of Wichita's effort to effectively manage this resource. In 2007, the city of Wichita began using Phase I of the Equus Beds Aquifer Storage and Recovery (ASR) project for large-scale artificial recharge of the Equus Beds aquifer. The ASR project uses water from the Little Arkansas River - either pumped from the river directly or from wells in the riverbank that obtain their water from the river by induced infiltration - as the source of artificial recharge to the Equus Beds aquifer (City of Wichita, 2009).

Scientific Investigations Map↗
USGS2004

Assessment of ground-water withdrawals at municipal industrial parks in Puerto Rico, 2000

An assessment of ground-water withdrawals at municipal industrial parks throughout Puerto Rico was conducted to investigate the effect of ground-water usage on nearby surface- and ground-water resources. Water-bearing strata were divided into four generalized hydrogeologic units: (1) fissured aquifers (including karst and non-karst limestone); (2) intergranular aquifers; (3) intergranular aquifers overlying fissured rock units; and (4) strata with local or limited ground-water resources. Approximately 49 percent of the municipal industrial parks are located in areas with local or limited ground-water resources, 29 percent overlie intergranular aquifers, 13 percent overlie fissured aquifers, and 9 percent overlie intergranular units that overlie fissured rock units. Hydrogeologic data for the generalized hydrogeologic units were compiled from published U.S. Geological Survey reports. Depths to ground water near industrial parks range from approximately 20 to 400 feet in the fissured aquifers, 6 to 65 feet in coastal intergranular aquifers, 3 to 30 feet in intergranular aquifers overlying fissured rock units, and 1 to 100 feet in strata with local or limited ground-water resources. Aquifer transmissivities near industrial parks range from approximately 100,000 feet squared per day in the fissured aquifers to less than 100 feet squared per day in the strata with local or limited ground-water resources. Well construction data were compiled from published U.S. Geological Survey reports, drillers? logs, and unpublished reports. Specific capacity for wells near industrial parks ranges from approximately 100 gallons per minute per foot of drawdown in the fissured aquifer at Manati to approximately 0.1 gallon per minute per foot of drawdown in strata with local and limited ground-water resources at Bayamon. Reported well yields near industrial parks ranges from 2,800 gallons per minute in the intergranular aquifer at Santa Isabel to approximately 3 gallons per minute in strata with local and limited ground-water resources at Adjuntas. Historical ground-water-level data from U.S. Geological Survey observation wells were used to define ground-water levels trends in the vicinity of industrial parks. Areas showing ground-water level declines, and therefore possible aquifer over-development, are located in Barceloneta and Guayama. Rising ground-water levels were noted in the vicinity of industrial parks at Florida, Ponce, and Yauco. Ground-water withdrawal data were compiled from site visits to the industrial facilities and from information provided by Puerto Rico Department of Natural and Environmental Resources. Total ground-water withdrawal at the municipal industrial parks was estimated to be 1.6 million gallons per day. Most withdrawals were from intergranular coastal aquifers, which accounted for about two thirds of the ground-water withdrawals. Municipal industrial parks with substantial ground-water withdrawals are located in Bayamon, Caguas, Humacao, and Ponce.

Scientific Investigations Report↗
USGS1981

Manual for leveling at gaging stations in North Carolina

This manual was prepared to serve several purposes in the U.S. Geological Survey North Carolina District. This manual sets forth District policy as to frequency of levels, accuracy criteria, procedures for checking the datum and setting of the various types of gages, general rules to follow in establishing the original datum of a gage, and contains sample notes to be used as guides in level notekeeping. The manual also serves as a training tool in that the reasoning behind District policy is explained and reasons are given for following the recommended techniques to assist in a better understanding of the purpose of levels and maintaining gage datum.

North Carolina↗
USGS1953

Occurrences of uranium-bearing minerals in the St. Kevin District, Lake County, Colorado

Two hundred and seventy-one prospect pits, mine dumps, or mine workings within the Sugar Loaf-St. Kevin mining districts and vicinity were tested for radioactivity by the U.S. Geological Survey in 1951 during six weeks of investigation on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission. One hundred and twenty-two weak radioactivity anomalies were found in the St. Kevin district and vicinity, and eight slight anomalies were noted in the Sugar Loaf district, which adjoins the St. Kevin district on the south. Most of the radioactivity anomalies were found in igneous and metamorphic rocks of pre-Cambrian age, but some were found in metalliferous veins of Tertiary age. Samples of altered granite or schist contain as much as 0.065 percent uranium, probably in the form of secondary uranium minerals. Samples of vein material contain as much as 0.013 percent uranium, also probably in the form of secondary uranium minerals. At only a few localities has the identity of the uranium-bearing minerals been determined. Torbernite, associated with turquoise, malachite, and chrysocolla, occurs as disseminations and fracture coatings in altered granite at the Josie May turquoise mine; metatobernite is disseminated in granite at the Turquoise Chief mine. Commonly the limonite-stained fractures in the altered granite and schist are radioactive; metatorbernite has been identified in limonite stain at one locality. A uranium-variety of florencite, a hydrous cerium aluminum phosphate, is disseminated in the granite on the dump of a mine just west of the St. Kevin district, and autunite (?) is disseminated in fine-grained, highly silicified rock in the northeastern part of the St. Kevin district. None of the uranium occurrences are of commercial importance. They are for the most part in non-glaciated terrane, which has been subjected to a very long period of weathering. Thus, chemical leaching within the zone of weathering may have greatly reduced the uranium content of material near the surface, and occurrences of even small quantities of secondary uranium minerals might be related to stronger, primary concentrations at depth.

Colorado↗
USGS2000

Geologic map of the Sappho Patera Quadrangle (V-20), Venus

The Sappho Patera quadrangle (V–20) of Venus is bounded by 0° and 30° East longitude, 0° and 25° North latitude. It is one of 62 quadrangles covering the entire planet at a scale of 1:5,000,000. The quadrangle derives its name from Sappho Patera, a large rimmed depression (diameter about 225 km) lying on top of a shield-shaped mountain named Irnini Mons. Sappho, a noted Greek poet born about 612 B.C., spent most of her life on the island of Lesbos. All of her works were burned in 1073 by order of ecclesiastical authorities in Rome and Constantinople. What little survives was discovered in 1897 as parts of papier mâché coffins in the Fayum (Durant, 1939). The Sappho Patera quadrangle includes the central portion of Eistla Regio, an elongated, moderately elevated (relief ~1 km) region extending for about 7,500 km west-northwestward from the west end of Aphrodite Terra. It is generally interpreted to be the surface manifestation of one or more mantle plumes (Phillips and Malin, 1983; Stofan and Saunders, 1990; Kiefer and Hager, 1991; Senske and others, 1992; Grimm and Phillips, 1992; Solomon and others, 1992). Eistla Regio is dominated by several large volcanic features. All or parts of four of these occur within the Sappho Patera quadrangle: the eastern flank of Gula Mons, Irnini Mons, Anala Mons, and Kali Mons. The quadrangle also includes eight named coronae: Nehalennia, Sunrta, Libera, Belet-Ili, Gaia, Asomama, Rabzhima, and Changko. A major rift extends from Gula Mons in the northwestern corner of the quadrangle to Libera Corona near the east border. East of Irnini and Anala Montes this rift is named Guor Linea; west of the montes it is named Virtus Linea. In addition to these major features, the Sappho Patera quadrangle includes numerous smaller volcanic flows and constructs, several unnamed coronae and corona-like features, a complex array of faults, fractures, and wrinkle ridges, and extensive plains that are continuous with the regional plains that constitute about 80% of the surface of Venus (Masursky and others, 1980). This area is geologically interesting because it contains examples of most globally important types of features and deposits and is an excellent area to study the temporal and genetic relations among plains, rifts, coronae, and large shield volcanoes. The temporal relations displayed in this quadrangle can provide useful constraints on models for venusian tectonic style (McGill, 1994b).

IMAP↗
USGS2014

Earth‐tides shown by fluctuations of water‐levels in wells in New Mexico and Iowa

It is quite generally known that ocean‐tides produce fluctuations of the water‐level in wells of the artesian type located close to the seashore by periodically changing the external load on the aquifer [see 1 of “References” at end of paper]. Fluctuations of ground‐water as a result of earth‐tides, however, are not generally known although they were observed and studied in a flooded coal‐mine in Europe [2] as early as 1879, and later 1905 to 1912 in wells in South Africa [3]. The phenomena of earth‐tides first came to the attention of the writer in March, 1938, when studying fluctuations of the water‐level In an artesian well near Carlsbad, New Mexico, recorded on charts of a water‐stage recorder, which had an approximately semidiurnal period. Because of the distance from the ocean, about 500 miles, and the altitude of the water‐bearing formation, about 2700 feet, it appeared that the fluctuations could not be the result of ocean‐tides. Neither did it appear they could be the result of other natural phenomena such as changing air‐pressure or changes in water‐level of a nearby lake and river. There was no pumpage from the aquifer, so the fluctuations of the water could not be caused by pumping. T. M. Cramer, Resident Manager of the United States Potash Company at Carlsbad, New Mexico, suggested that the fluctuations must be the result of some lunar attraction. Further study of the fluctuation was made by Dr. C. V. Theis, of the United States Geological Survey, and the writer, whereby the effect of changing air‐pressure was eliminated by correcting the water‐levels to an assumed constant atmospheric pressure. In this study it was demonstrated after applying the barometric correction that the remaining fluctuations were fairly regular and progressed with the transit of the Moon. It was also demonstrated that the fluctuations were of the greatest amplitude during the period of new Moon. Further work by W. E. Hale, of the United States Geological Survey, and the writer, has shown that the fluctuations were much more regular and of greater amplitude during the periods of new and full Moon than during the first and third quarters. It was, therefore, concluded that they are related to true earth‐tides. A preliminary note was published in the Transactions of the American Geophysical Union for 1938 [4].

New Mexico↗
USGS2008

Internships, employment opportunities, and research grants

As an unbiased, multidisciplinary science organization that focuses on biology, geography, geology, geospatial information, and water, the U.S. Geological Survey (USGS) is dedicated to the timely, relevant, and impartial study of the landscape, our natural resources, and the natural hazards that threaten us. Opportunities for undergraduate and graduate students and faculty to participate in USGS science are available through the selected programs described below. Please note: U.S. citizenship is required for all positions, although some noncitizens may be eligible in rare circumstances.

General Information Product↗
USGS2004

Geologic Map of Pipe Spring National Monument and the Western Kaibab-Paiute Indian Reservation, Mohave County, Arizona

The digital map publication, compiled from previously published and unpublished data and new mapping by the author, represents the general distribution of surficial and bedrock geology in Pipe Spring National Monument and vicinity, including the following 1:24,000-scale U.S. Geological Survey (USGS) quadrangles: Moccasin, Kaibab, Pipe Valley, and Pipe Spring. Together with the accompanying geologic description pamphlet, it presents current knowledge of the geologic structure and stratigraphy of the area covered. The database identifies map units that are classified by age and lithology following the stratigraphic nomenclature of the USGS. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller. Note: The extent of this database conforms to the boundaries of the four quadrangles listed above; however, the topographic base maps produced by the USGS for the Moccasin and Kaibab quadrangles extend slightly to the north of the 37-degree latitude line that should define the northern limit of these 7.5- minute quadrangles. Thus, if this database is overlain with a digital file of quadrangle boundaries there is a mismatch.

Scientific Investigations Map↗
USGS2016

Network global navigation satellite system surveys to harmonize American and Canadian datum for the Lake Champlain Basin

Historically high flood levels were observed during flooding in Lake Champlain and the Richelieu River from late April through May 2011. Flooding was caused by record spring precipitation and snowmelt from the third highest cumulative snowfall year on record, which included a warm, saturated late spring snowpack. Flood stage was exceeded for a total of 67 days from April 13 to June 19, 2011. During this flooding, shoreline erosion and lake flood inundation were exacerbated by wind-driven waves associated with local fetch and lake-wide seiche effects. In May 2011, a new water-surface-elevation record was set for Lake Champlain. Peak lake-level water-surface elevations varied at the three U.S. Geological Survey lake-level gages on Lake Champlain in 2011. The May 2011 peak water-surface elevations for Lake Champlain ranged from 103.20 feet above the National Geodetic Vertical Datum of 1929 at the northern end of Lake Champlain (at its outlet into the Richelieu River at Rouses Point, New York) to 103.57 feet above the National Geodetic Vertical Datum of 1929 at the southern end of the Lake in Whitehall, New York. The water-surface elevations for the Richelieu River in Canada are referenced to a different vertical datum than are those in Lake Champlain in the United States, which causes difficulty in assessing real-time flood water-surface elevations and comparing of flood peaks in the Lake Champlain Basin in the United States and Canada. On March 19, 2012, as a result of the flood event of April and May 2011, the Governments of Canada and the United States asked the International Joint Commission to draft a plan of study to examine the causes and the effects of the spring 2011 flooding on Lake Champlain and the Richelieu River and develop potential mitigation measures. Specific challenges noted by the International Lake Champlain-Richelieu River Technical Working Group (established by the International Joint Commission) included harmonization of vertical datums within the drainage basin. Harmonization of the vertical datum discrepancy is needed for flood assessment and future efforts to model the flow of water through the Lake Champlain Basin in the United States and Canada. In April 2015, the U.S. Geological Survey and Environment Canada began a joint field effort with the goal of obtaining precise elevations representing a common vertical datum for select reference marks used to determine water-surface elevations throughout Lake Champlain and the Richelieu River. To harmonize the datum difference between the United States and Canada, Global Navigation Satellite System surveys were completed at nine locations in the Lake Champlain Basin to collect simultaneous satellite data. These satellite data were processed to produce elevations for two reference marks associated with dams and seven reference marks associated with active water-level gages (lake gages in Lake Champlain and streamgages in the Richelieu River) to harmonize vertical datums throughout the Lake Champlain Basin. The Global Navigation Satellite System surveys were completed from April 14 to 16, 2015, at locations ranging from southern Lake Champlain near Whitehall, New York, to the northern end of the Richelieu River in Sorel, Quebec, at its confluence with the St. Lawrence River in Canada. Lake-gage water-surface elevations determined during the 3 days of surveys were converted to water-surface elevations referenced to the North American Vertical Datum of 1988 by using calculated offsets and historical water-surface elevations. In this report, an “offset” refers to the adjustment that needs to be applied to published data from a particular gage to produce elevation data referenced to the North American Vertical Datum of 1988. Offsets presented in this report can be used in the evaluation of water-surface elevations in a common datum for Lake Champlain and the Richelieu River. In addition, the water-level data referenced to the common datum (as determined from the offsets) may be used to calibrate flow models and support future modeling studies developed for Lake Champlain and the Richelieu River.

New York, Quebec, Vermont↗
USGS2012

Lead and strontium isotopes and related trace elements as genetic tracers in the Upper Cenozoic rhyolite-basalt association of the Yellowstone Plateau volcanic field

Supported by various field geologic and petrologic data, the contents of Pb, U, Th, Rb, and Sr and the isotopic compositions of Pb and Sr for upper Cenozoic volcanic rocks of the Yellowstone Plateau volcanic field are consistent with the hypothesis of derivation of the basaltic and rhyolitic magmas by partial melting of distinct source regions in the upper mantle and lower crust, respectively. All the basalt samples analyzed but one have systematically lower values of 207 Pb/ 204 Pb and 87 Sr/ 86 Sr than the rhyolites. The values of 206 Pb/ 204 Pb are smaller, and 87 Sr/ 86 Sr are mostly larger than known values in oceanic basalts. In all but one case, the values of 207 Pb/ 204 Pb are higher than expected from an extrapolation of known values in oceanic basalts to less radiogenic values of 206 Pb/ 204 Pb. Because there are no xenoliths, phenocrysts are only moderate to sparse in abundance, REE patterns are low and flat at the radiogenic end of lead isotopic compositions, several values of Rb/Sr are low, and 80% of the basalt samples form a well-developed secondary isochron separate from the rhyolites, we favor an interpretation for basalt genesis wherein isotopic signatures of most mafic magmas were attained in a continental ‘keel’ of mantlelike character about 2.6 b.y. old or somewhat older attached to the crust, and these signatures were unaltered by magma passage through the crust. At the very least, the current data continue to cast serious doubt as to the inevitability of crustal contamination for basaltic magma intruding the continental environment and postulate that much can be learned about the mantle under continents through the study of continental basalts. One basalt unit with an unusually low value of 207 Pb/ 204 Pb and an 87 Ar/ 86 Ar less than 0.704 may represent subcontinental ‘keel’-derived magma that rose unaltered to the surface. Our data also are not consistent with formation of this rhyolite-basalt association primarily by such processes as crystal fractionation, separation of immiscible silicate liquids from a common parental magma, or fractional melting of a homogeneous source. Rather as a conceptual model, we envision large mafic intrusions to have been injected into the lower crust resulting in rhyolite generation through partial anatexis of the adjacent wall rocks which probably had a 206 Pb/ 204 Pb < 17 and 87 Sr/ 86 Sr > 0.709; a model that has much in common with that proposed by Holmes (1931). All the other hypotheses listed have the necessary added complication that either the basalt or the rhyolite or both become contaminated after the two magma types separated, have problems accounting for the lack of igneous rocks of intermediate compositions or production of such large volumes of rhyolitic material (∼5000 km 3 ), and fail to explain why rhyolitic magma is not a more common occurrence in the ocean basin. We appeal to bouyancy of rhyolites to generate a barrier for basalt magma migration and account for the great preponderance of rhyolite relative to basalt at the surface. Furthermore, the complex isotopic picture in the rhyolites indicates that many of these magmas interacted with the upper crustal geologic units that they traversed. The interactions involved diverse processes, probably including reacton with hydrothermal fluids or hydrothermally altered rocks at high levels as well as by contamination with Phanerozoic sedimentary and Precambrian crystalline rocks at deeper levels. At the very least, we feel our study adds a cautionary note to the currently increasingly popular hypothesis that differentiation of basalt or gabbro magmas to rhyolite or granite (as distinct from tonalite or dacite) is a common occurrence and is therefore an important continential building process. Models for formation of rhyolite and granite predominantly by reworking of crust (anatexis) must still be considered. The primitive Archean mantle of the region was characterized by higher Rb/Sr, U/Pb, and Th/U values than are typical of modern suboceanic mantle. The mantle residuum within the continental subcrustal lithosperic ‘keel’ that resulted from the Archean crustal differentiation event probably was depleted in Rb/Sr and U/Pb, and the crust was correspondingly enriched in these ratios. The crust probably was further differentiated by an Archean high-grade metamorphism, during or after the primary event, into a granulitic lower crust depleted in U/Pb and Rb/Sr and a lower-grade upper crust enriched in these ratios.

Journal of Geophysical Research Solid Earth↗
USGS2008

Coast salish and U.S. Geological Survey: Tribal journey water quality project

The ancestral waters of the Coast Salish People, the Salish Sea, comprise a large inland sea contained within both United States (Puget Sound) and Canadian (Georgia Strait) territory. The Salish Sea is home to more than 220 species of fish, 29 species of marine mammals, more than 40 species of commercial and recreationally harvested invertebrates, and numerous resident and migratory bird species (Washington Sea Grant Program, 2000). Unfortunately, at least 60 of these marine based species are listed as threatened, endangered or of concern (Fraser and others, 2006), many of which sustained Coast Salish for millennia and are of essential cultural importance. The cumulative impacts of human activities and climate change are deteriorating coastal ecosystems and accelerating the loss of ecologically and culturally important marine resources. Watershed modifications, coastal development and industrial activities are altering river and tidal flow, sediment transport, and nutrient delivery all across the region, leading to the break down of ecosystem functions and decreasing biodiversity, thus changing the face of the Salish Sea. A cooperative trans-boundary partnership between the U.S. Environmental Protection Agency (USEPA) and the Government of Canada has identified Salish Sea indicators of health. Several of these indicators have been noted as having degrading quality including urbanization and forest change, river, stream, and lake quality, marine species at risk, toxics in harbor seals, and marine water quality conditions (USEPA, 2008). The functioning of the Salish Sea ecosystem is increasingly threatened by ever more frequent observations and expanding zones of anoxia. The complexities of monitoring, protecting, and restoring such a large and diverse geographical area are exacerbated by a political border. The Coast Salish Peoples and U.S. Geological Survey (USGS) have commenced on a partnership to examine water quality throughout the Georgia Straits and Puget Sound, blending tradition and science, in response to this deterioration of coastal environments and loss of essential habitats and marine resources of cultural and ecological importance throughout the ancestral waters of the Salish Sea. This report describes the Coast Salish Tribal Journey Water Quality Project, its inception, the results of the 2008 Tribal Journey project, lessons learned, and recommendations for future directions.

Report↗
USGS1996

Small watershed studies: Analytical approaches for understanding ecosystem response to environmental change

Biogeochemical studies in small watersheds provide an analytical approach to understand how ecosystems respond to natural climatic variations and human-induced environmental change. Small watersheds, usually less than 5 km2, are small enough to permit characterization and understanding of ecosystem processes within relatively simple, homogeneous biological and physical settings; yet they are large enough to incorporate more complex processes and element cycles than can be studied at plot scales. Watersheds comprise discrete hydrochemical environments allowing quantification of hydrologic, element, and energy budgets. Element budgets, or mass balances, can be quantified as the difference between the mass of a solute that enters a watershed in wet and dry deposition and leaves a watershed in streamflow. Element budgets are primary tools used to investigate biogeochemical processes. Monitoring various aspects of element budgets to assess ecosystem health and stability is analogous to measuring the pulse or blood chemistry of a patient. Monitoring streamwater chemistry, basic climate, soil, and biotic variables provide a means to integrate complex biogeochemical processes and evaluate trends in water quality. Small watershed studies provide a scientific basis to develop predictive models of watershed function. Major emphases of small watershed studies include investigation of hydrologic and chemical responses to natural climate variation, anthropogenic stressors, and alternate forest-management practices. The nature and significance of biogeochemical research in small watersheds is reviewed by Moldan and Cerny (1994). The U.S. Geological Survey, U.S. Department of Agriculture Forest Service, and other federal agencies support several long-term small watershed studies to provide insight into a variety of ecosystem processes. Long-term records are essential to distinguish trends resulting from natural climatic variations or other stressors. The following sites, with noted periods of records, are examples of intensively studied forested watersheds in eastern USA supported by federal agencies: ■ Coweeta Hydrologic Laboratory, North Carolina, (1939-present), Swank and Crossley (1988). ■ Hubbard Brook Experimental Forest, New Hampshire, (1956-present), Bormann and Likens (1979). ■ Sleepers River Research Watershed, Vermont, (1958-present), Shanley et al. (1995). ■ Walker Branch Watershed, Tennessee, (1967-present), Johnson and Van Hook (1989). ■ Catoctin Mountains Research Site, Maryland, (1982-present), Rice and Bricker (1995). ■ Catskill Stream Network, New York, (1983- present), Murdoch and Stoddard (1992). ■ Panola Mountain Research Watershed, Georgia, (1985-present), Huntington et al. (1993). Small watershed studies also provide essential baseline information for understanding variations in water quality and element cycling in "pristine" ecosystems that can be used as benchmarks to evaluate anthropogenic impacts and alternate watershed management practices. This paper provides examples of how analytical tools developed through watershed research provide insight into ecosystem processes and can contribute to the management of watershed resources.

Conference Paper↗
USGS2019

Windows to the deep 2018: Exploration of the southeast US Continental margin

Windows to the Deep 2018: Exploration of the Southeast US Continental Margin was a 36-day expedition aboard NOAA Ship Okeanos Explorer to acquire data on priority exploration areas identified by the ocean management and scientific communities. This expedition involved high-resolution multibeam sonar mapping and ROV dives, ranging from 340 m to 3,400 m depth, across the southeast US continental margin. Operations primarily targeted areas with potential to host deep-sea coral and sponge communities, including mounds, ridges, and terraced features on the continental slope. Dive sites also included maritime heritage sites, a submarine landslide feature, and several submarine canyon slopes, some of which exhibited evidence of active cold seeps. High biological abundance was noted at six of 17 dive sites, three of which also had high biological diversity. Additionally, deep-sea corals or sponges were observed on every dive except one, which was dedicated to gas seep exploration.

Atlantic Ocean, Blake Plateau, Stetson Mesa↗
USGS2017

Coal-tar-based pavement sealants—a potent source of PAHs

P avement sealants are applied to the asphalt pavement of many parking lots, driveways, and even playgrounds in North America (Figure 1), where, when first applied, they render the pavement glossy black and looking like new. Sealant products used commercially in the central, eastern, and northern United States typically are coal-tarbased, whereas those used in the western United States typically are asphalt-based. Although the products look similar, they are chemically different. Coal-tarbased pavement sealants typically are 25-35 percent (by weight) coal tar or coal-tar pitch, materials that are known human carcinogens and that contain high concentrations of polycyclic aromatic hydrocarbons (PAHs) and related chemicals (unless otherwise noted, all Figure 1. Pavement sealant is commonly used to seal parking lots, playgrounds, and driveways throughout the United States. Sealants used in the central, northern, eastern, and southern United States typically contain coal tar or coal-tar pitch, both of which are known human carcinogens. Photos by the U.S. Geological Survey. data in this article are from Mahler et al. 2012 and references therein).

Lakeline↗
USGS1999

Mass-balance measurements in Alaska and suggestions for simplified observation programs

US Geological Survey glacier fieldwork in Alaska includes repetitious measurements, corrections for leaning or bending stakes, an ability to reliably measure seasonal snow as deep as 10 m, absolute identification of summer surfaces in the accumulation area, and annual evaluation of internal accumulation, internal ablation, and glacier‐thickness changes. Prescribed field measurement and note‐taking techniques help eliminate field errors and expedite the interpretative process. In the office, field notes are transferred to computerized spreadsheets for analysis, release on the World Wide Web, and archival storage. The spreadsheets have error traps to help eliminate notetaking and transcription errors. Rigorous error analysis ends when mass‐balance measurements are extrapolated and integrated with area to determine glacier and basin mass balances. Unassessable errors in the glacier and basin mass‐balance data reduce the value of the data set for correlations with climate change indices. The minimum glacier mass‐balance program has at least three measurement sites on a glacier and the measurements must include the seasonal components of mass balance as well as the annual balance.

Geografiska Annaler, Series A: Physical Geography↗