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USGS2004

Preliminary integrated geologic map databases for the United States: Minnesota, Wisconsin, Michigan, Illinois, and Indiana

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carolina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Illinois, Indiana, Michigan, Minnesota, Wisconsin↗

USGS2005

Preliminary integrated geologic map databases for the United States: Alabama, Florida, Georgia, Mississippi, North Carolina, and South Carolina

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the digital version of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000 which is currently being prepared by the U.S. Geological Survey. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. In a few cases, new digital compilations were prepared (e.g. OH, SC, SD) or existing paper maps were digitized (e.g. KY, TX). For Alaska and Hawaii, new regional maps are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO (.e00) export files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental data tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Alabama, Florida, Georgia, Mississippi, North Caro↗

USGS2005

Preliminary integrated geologic map databases for the United States: Kentucky, Ohio, Tennessee, and West Virginia

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carloina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Kentucky, Ohio, Tennessee, West Virginia↗

USGS2005

Preliminary integrated geologic map databases for the United States: Delaware, Maryland, New York, Pennsylvania, and Virginia

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carloina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS2005

Preliminary integrated geologic map databases for the United States: Central states: Montana, Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Iowa, Missouri, Arkansas, and Louisiana

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the digital version of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000 which is currently being prepared by the U.S. Geological Survey. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. In a few cases, new digital compilations were prepared (e.g. OH, SC, SD) or existing paper maps were digitized (e.g. KY, TX). For Alaska and Hawaii, new regional maps are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO (.e00) export files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental data tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines. This is the first version of this product and it will be subsequently updated to include four additional states (North Dakota, South Dakota, Nebraska, and Iowa)

Arkansas, Colorado, Iowa, Kansas, Louisiana, Misso↗

USGS2011

Factors influencing riverine fish assemblages in Massachusetts

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, Massachusetts Department of Environmental Protection, and the Massachusetts Department of Fish and Game, conducted an investigation of fish assemblages in small- to medium-sized Massachusetts streams. The objective of this study was to determine relations between fish-assemblage characteristics and anthropogenic factors, including impervious cover and estimated flow alteration, relative to the effects of environmental factors, including physical-basin characteristics and land use. The results of this investigation supersede those of a preliminary analysis published in 2010. Fish data were obtained for 669 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select fish metrics - species richness, abundance of individual species, and abundances of species grouped on life history traits - responsive to flow alteration. The contributing areas to the fish-sampling sites were delineated and used with a geographic information system to determine a set of environmental and anthropogenic factors that were tested for use as explanatory variables in regression models. Reported and estimated withdrawals and return flows were used together with simulated unaltered streamflows to estimate altered streamflows and indicators of flow alteration for each fish-sampling site. Altered streamflows and indicators of flow alteration were calculated on the basis of methods developed in a previous U.S. Geological Survey study in which unaltered daily streamflows were simulated for a 44-year period (water years 1961-2004), and streamflow alterations were estimated by use of water-withdrawal and wastewater-return data previously reported to the State for the 2000-04 period and estimated domestic-well withdrawals and septic-system discharges. A variable selection process, conducted using principal components analysis and Spearman rank correlation, was used to select a set of 15 non-redundant environmental and anthropogenic factors to test for use as explanatory variables in the regression analyses. Twenty-one fish species were used in a multivariate analysis of fish-assemblage patterns. Results of nonmetric multidimensional scaling and hierarchical cluster analysis were used to group fish species into fluvial and macrohabitat generalist habitat-use classes. Two analytical techniques, quantile regression and generalized linear modeling, were applied to characterize the association between fish-response variables and environmental and anthropogenic explanatory variables. Quantile regression demonstrated that as percent impervious cover and an indicator of percent alteration of August median flow from groundwater withdrawals increase, the relative abundance and species richness of fluvial fish decrease. The quantile regression plots indicate that (1) as many as seven fluvial fish species are expected in streams with little flow alteration or impervious cover, (2) no more than four fluvial fish species are expected in streams where flow alterations from groundwater withdrawals exceed 50 percent of the August median flow or the percent area of impervious cover exceeds 15 percent, and (3) few fluvial fish remain at high rates of withdrawal (approaching 100 percent) or high rates of impervious cover (between 25 and 30 percent). Three generalized linear models (GLMs) were developed to quantify the response of fluvial fish to multiple environmental and anthropogenic variables. All variables in the GLM equations were demonstrated to be significant (p less than 0.05, with most less than 0.01). Variables in the fluvial-fish relative-abundance model were channel slope, estimated percent alteration of August median flow from groundwater withdrawals, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the fluvial-fish species-richness model were drainage area, channel slope, total undammed reach length, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the brook trout relativeabundance model were drainage area, percent open water, and percent impervious cover. The variability explained by the GLM models, as measured by the pseudo R2, ranged from 18.2 to 34.6, and correlations between observed and predicted values ranged from 0.50 to 0.60. Results of GLM models indicated that, keeping all other variables the same, a one-unit (1 percent) increase in the percent depletion of August median flow would result in a 0.9-percent decrease in the relative abundance (in counts per hour) of fluvial fish. The results of GLM models also indicated that a unit increase in impervious cover (1 percent) resulted in a 3.7-percent decrease in the relative abundance of fluvial fish, a 5.4-percent decrease in fluvial-fish species richness, and an 8.7-percent decrease in brook trout relative abundance.

Massachusetts↗

USGS2018

Greenhouse gas emissions from diverse Arctic Alaskan lakes are dominated by young carbon

Climate-sensitive Arctic lakes have been identified as conduits for ancient permafrost-carbon (C) emissions and as such accelerate warming. However, the environmental factors that control emission pathways and their sources are unclear; this complicates upscaling, forecasting and climate-impact-assessment efforts. Here we show that current whole-lake CH 4 and CO 2 emissions from widespread lakes in Arctic Alaska primarily originate from organic matter fixed within the past 3–4 millennia (modern to 3,300 ± 70 years before the present), and not from Pleistocene permafrost C. Furthermore, almost 100% of the annual diffusive C flux is emitted as CO 2 . Although the lakes mostly processed younger C (89 ± 3% of total C emissions), minor contributions from ancient C sources were two times greater in fine-textured versus coarse-textured Pleistocene sediments, which emphasizes the importance of the underlying geological substrate in current and future emissions. This spatially extensive survey considered the environmental and temporal variability necessary to monitor and forecast the fate of ancient permafrost C as Arctic warming progresses.

Alaska↗

USGS2008

Geological, geochemical, and geophysical studies by the U.S. Geological Survey in Big Bend National Park, Texas

Big Bend National Park (BBNP), Tex., covers 801,163 acres (3,242 km 2 ) and was established in 1944 through a transfer of land from the State of Texas to the United States. The park is located along a 118-mile (190-km) stretch of the Rio Grande at the United States-Mexico border. The park is in the Chihuahuan Desert, an ecosystem with high mountain ranges and basin environments containing a wide variety of native plants and animals, including more than 1,200 species of plants, more than 450 species of birds, 56 species of reptiles, and 75 species of mammals. In addition, the geology of BBNP, which varies widely from high mountains to broad open lowland basins, also enhances the beauty of the park. For example, the park contains the Chisos Mountains, which are dominantly composed of thick outcrops of Tertiary extrusive and intrusive igneous rocks that reach an altitude of 7,832 ft (2,387 m) and are considered the southernmost mountain range in the United States. Geologic features in BBNP provide opportunities to study the formation of mineral deposits and their environmental effects; the origin and formation of sedimentary and igneous rocks; Paleozoic, Mesozoic, and Cenozoic fossils; and surface and ground water resources. Mineral deposits in and around BBNP contain commodities such as mercury (Hg), uranium (U), and fluorine (F), but of these, the only significant mining has been for Hg. Because of the biological and geological diversity of BBNP, more than 350,000 tourists visit the park each year. The U.S. Geological Survey (USGS) has been investigating a number of broad and diverse geologic, geochemical, and geophysical topics in BBNP to provide fundamental information needed by the National Park Service (NPS) to address resource management goals in this park. Scientists from the USGS Mineral Resources and National Cooperative Geologic Mapping Programs have been working cooperatively with the NPS and several universities on several research studies within BBNP. Because the last geologic map of the entire BBNP was published in the 1960s, one of the primary goals of the USGS is to provide a new geologic map of BBNP at a scale 1:100,000; this work is ongoing among the USGS, NPS, the Texas Bureau of Economic Geology, and university scientists. This USGS Circular summarizes eight studies funded and primarily carried out by the USGS, but it is not intended to be a comprehensive reference of work conducted in BBNP. This Circular describes topical research of the recently completed interdisciplinary USGS project, which has provided information leading to a more complete understanding of the following topics in BBNP: Tectonic and geologic history (Chapters 1, 2, and 3), Age and formation processes of a skarn mineral deposit (Chapter 4), Geoenvironmental effects of abandoned mercury mines (Chapter 5), Age, source, and geochemistry of surface and subsurface water resources (Chapter 6), Isotopic tracing of food sources of bears (Chapter 7), and Geophysical characteristics of surface and subsurface geology (Chapter 8). Additional information and the geochemical and geophysical data of the USGS studies in BBNP are available on line at http://minerals.cr.usgs.gov/projects/big_bend/index.html.

Texas↗

USGS2000

Digital geologic map of the Butler Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report 00-145, is a digital geologic map database of the Butler Peak 7.5' quadrangle that includes (1) ARC/INFO ( Environmental Systems Research Institute ) version 7.2.1 Patch 1 coverages, and associated tables, (2) a Portable Document Format (.pdf) file of the Description of Map Units, Correlation of Map Units chart, and an explanation of symbols used on the map, btlrpk_dcmu.pdf, (3) a Portable Document Format file of this Readme, btlrpk_rme.pdf (the Readme is also included as an ascii file in the data package), and (4) a PostScript plot file of the map, Correlation of Map Units, and Description of Map Units on a single sheet, btlrpk.ps. No paper map is included in the Open-File report, but the PostScript plot file (number 4 above) can be used to produce one. The PostScript plot file generates a map, peripheral text, and diagrams in the editorial format of USGS Geologic Investigation Series (I-series) maps.

California↗

USGS2000

Chemical characteristics of urban stormwater sediments and implications for environmental management, Maricopa County, Arizona

Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic contribution of these elements to the sediment chemistry. Concentrations, however, were not at levels that would require soil remediation according to guidelines of the U.S. Environmental Protection Agency. Arsenic concentrations generally were above recommended values for remediation at a few sites, but these concentrations seem to reflect geologic rather than anthropogenic factors. Several organochlorine compounds no longer in use were ubiquitous in the Phoenix area, although concentrations generally were low. Chlordane, DDT and its decay products DDE and DDD, dieldrin, toxaphene, and PCBs were found at almost all sites sampled, although some of the pesticides in which these compounds are found have been banned for almost 30 years. A few sites showed exceptionally high concentrations of organochlorine compounds. On the basis of published guidelines, urban stormwater sediments do not appear to constitute a major regional environmental problem with respect to the chemical characteristics investigated here. At individual sites, high concentrations of organic compounds - chlordane, dieldrin, PCBs, and toxaphene - may require some attention. The possible environmental hazard presented by low-level organochlorine contamination is not addressed in this paper; however, high levels of toxicity in urban sediments are difficult to explain. Sediment toxicity varied significantly with time, which indicates that these tests should be evaluated carefully before they are used for management decisions.Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic contribution of these elements to the sediment chemistry. Concentrations, however, were not at levels that would require soil remediation according to guidelines of the U.S. Environmental Protection Agency. Arsenic concentrations generally were above recommended values for remediation at a few sites, but these concentrations seem to reflect geologic rather than anthropogenic factors. Several organochlorine compounds no longer in use were ubiquitous in the Phoenix area, although concentrations generally were low. Chlordane, DDT and its decay products DDE and DDD, dieldrin, toxaphene, and PCBs were found at almost all sites sampled, although some of the pesticides in which these compounds are found have been banned for almost 30 years. A few sites showed exceptionally high concentrations of organochlorine compounds. On the basis of published guidelines, urban stormwater sediments do not appear to constitute a major regional environmental problem with respect to the chemical characteristics investigated here. At individual sites, high concentrations of organic compounds - chlordane, dieldrin, PCBs, and toxaphene - may require some attention. The possible environmental hazard presented by low-level organochlorine contamination is not addressed in this paper; however, high levels of toxicity in urban sediments are difficult to explain. Sediment toxicity varied significantly with time, which indicates that these tests should be evaluated carefully before they are used for management decisions.

Environmental Management↗

USGS2018

Geologic map of the Washington West 30’ × 60’ quadrangle, Maryland, Virginia, and Washington D.C.

The Washington West 30’ × 60’ quadrangle covers an area of approximately 4,884 square kilometers (1,343 square miles) in and west of the Washington, D.C., metropolitan area. The eastern part of the area is highly urbanized, and more rural areas to the west are rapidly being developed. The area lies entirely within the Chesapeake Bay drainage basin and mostly within the Potomac River watershed. It contains part of the Nation's main north-south transportation corridor east of the Blue Ridge Mountains, consisting of Interstate Highway 95, U.S. Highway 1, and railroads, as well as parts of the Capital Beltway and Interstate Highway 66. Extensive Federal land holdings in addition to those in Washington, D.C., include the Marine Corps Development and Education Command at Quantico, Fort Belvoir, Vint Hill Farms Station, the Naval Ordnance Station at Indian Head, the Chesapeake and Ohio Canal National Historic Park, Great Falls Park, and Manassas National Battlefield Park. The quadrangle contains most of Washington, D.C.; part or all of Arlington, Culpeper, Fairfax, Fauquier, Loudoun, Prince William, Rappahannock, and Stafford Counties in northern Virginia; and parts of Charles, Montgomery, and Prince Georges Counties in Maryland. The Washington West quadrangle spans four geologic provinces. From west to east these provinces are the Blue Ridge province, the early Mesozoic Culpeper basin, the Piedmont province, and the Coastal Plain province. There is some overlap in ages of rocks in the Blue Ridge and Piedmont provinces. The Blue Ridge province, which occupies the western part of the quadrangle, contains metamorphic and igneous rocks of Mesoproterozoic to Early Cambrian age. Mesoproterozoic (Grenville-age) rocks are mostly granitic gneisses, although older metaigneous rocks are found as xenoliths. Small areas of Neoproterozoic metasedimentary rocks nonconformably overlie Mesoproterozoic rocks. Neoproterozoic granitic rocks of the Robertson River Igneous Suite intruded the Mesoproterozoic rocks. The Mesoproterozoic rocks are nonconformably overlain by Neoproterozoic metasedimentary rocks of the Fauquier and Lynchburg Groups, which in turn are overlain by metabasalt of the Catoctin Formation. The Catoctin Formation is overlain by Lower Cambrian clastic metasedimentary rocks of the Chilhowee Group. The Piedmont province is exposed in the east-central part of the map area, between overlapping sedimentary units of the Culpeper basin on the west and those of the Coastal Plain province on the east. In this area, the Piedmont province contains Neoproterozoic and lower Paleozoic metamorphosed sedimentary, volcanic, and plutonic rocks. Allochthonous mélange complexes on the western side of the Piedmont are bordered on the east by metavolcanic and metasedimentary rocks of the Chopawamsic Formation, which has been interpreted as part of volcanic arc. The mélange complexes are unconformably overlain by metasedimentary rocks of the Popes Head Formation. The Silurian and Ordovician Quantico Formation is the youngest metasedimentary unit in this part of the Piedmont. Igneous rocks include the Garrisonville Mafic Complex, transported ultramafic and mafic inclusions in mélanges, monzogranite of the Dale City pluton, and Ordovician tonalitic and granitic plutons. Jurassic diabase dikes are the youngest intrusions. The fault boundary between rocks of the Blue Ridge and Piedmont provinces is concealed beneath the Culpeper basin in this area but is exposed farther south. Early Mesozoic rocks of the Culpeper basin unconformably overlie those of the Piedmont and Blue Ridge provinces in the central part of the quadrangle. The north-northeast-trending extensional basin contains Upper Triassic to Lower Jurassic nonmarine sedimentary rocks. Lower Jurassic sedimentary strata are interbedded with basalt flows, and both Upper Triassic and Lower Jurassic strata are intruded by diabase of Early Jurassic age. The Bull Run Mountain fault, a major Mesozoic normal fault characterized by down-to-the-east displacement, separates rocks of the Culpeper basin from those of the Blue Ridge province on the west. On the east, the contact between rocks of the Culpeper basin and those of the Piedmont province is an unconformity, which has been locally disrupted by normal faults. Sediments of the Coastal Plain province unconformably overlie rocks of the Piedmont province along the Fall Zone and occupy the eastern part of the quadrangle. Lower Cretaceous deposits of the Potomac Formation consist of fluvial-deltaic gravels, sands, silts, and clays. Discontinuous fluvial and estuarine terrace deposits of Pleistocene and middle- to late-Tertiary age flank the modern Potomac River valley unconformable capping these Cretaceous strata and the crystalline basement where the Cretaceous has been removed by erosion. East of the Potomac River, the Potomac Formation is onlapped and unconformably overlain by a westward thinning wedge of marine sedimentary deposits of Late Cretaceous and early- and late-Tertiary age. Basement rooted Coastal Plain faults of Tertiary to Quaternary age occur along the Fall Zone and this part of the inner Coastal Plain. These Coastal Plain faults have geomorphic expression that appear to influence river drainage patterns. The geologic map of the Washington West quadrangle is intended to serve as a foundation for applying geologic information to problems involving land use decisions, groundwater availability and quality, earth resources such as natural aggregate for construction, assessment of natural hazards, and engineering and environmental studies for waste disposal sites and construction projects. This 1:100,000-scale map is mainly based on more detailed geologic mapping at a scale of 1:24,000.

Maryland, Virginia↗

USGS1983

The past is the key to the future

A new major frontier of geological research, which was initiated in the 1970's, involves predicting future geologic trends or events through study of the present and past, rather than trying to understand the past, often using what one knows about the present. Like most scientific frontiers, this one began from practical considerations—environmental concerns. The lack of formal recognition of this frontier results from fragmentation among many Federal agencies and highly focused mission-oriented programs ( e.g. , earthquake prediction, CO 2 , nuclear-energy safety, etc.). Most programs aim to predict only the next 50–100 years, but much longer periods of the past need to be studied to do this. Nuclear-waste disposal has sometimes been considered in terms of the next million years, a period of time permitting significant and broad geologic changes. Decreasing public interest in environmental concerns relegates many questions from the realm of applied research back to that of basic research. Most of these questions are so fascinating, however, that the frontier is still worth pursuing. Such questions include whether a phenomenon will or will not take place and the rates at which it can develop ( e.g. , how fast do rifts form, how fast can a caldera event begin, and how quickly can a glacial maximum arrive?). Common elements of all studies include the historic record, trends in the Quaternary, analogues in various periods of the geologic time scale, and allowance for phenomena never experienced before. Other examples of studies include the Cretaceous as a period of a climatic extreme, an especially interesting time period; establishing the amount of paleocloudiness, a particularly challenging and important research area; acid rain as a possible new phenomenon. Geochemistry has much to contribute to this frontier science.

Geochimica et Cosmochimica Acta↗

USGS2010

Effects of low-impact-development (LID) practices on streamflow, runoff quantity, and runoff quality in the Ipswich River Basin, Massachusetts: A summary of field and modeling studies

Low-impact-development (LID) approaches are intended to create, retain, or restore natural hydrologic and water-quality conditions that may be affected by human alterations. Wide-scale implementation of LID techniques may offer the possibility of improving conditions in river basins, such as the Ipswich River Basin in Massachusetts, that have run dry during the summer because of groundwater withdrawals and drought. From 2005 to 2008, the U.S. Geological Survey, in a cooperative funding agreement with the Massachusetts Department of Conservation and Recreation, monitored small-scale installations of LID enhancements designed to diminish the effects of storm runoff on the quantity and quality of surface water and groundwater. Funding for the studies also was contributed by the U.S. Environmental Protection Agency’s Targeted Watersheds Grant Program through a financial assistance agreement with Massachusetts Department of Conservation and Recreation. The monitoring studies examined the effects of replacing an impervious parking-lot surface with a porous surface on groundwater quality, installing rain gardens and porous pavement in a neighborhood of 3 acres on the quantity and quality of stormwater runoff, and installing a 3,000-ft2 (square-foot) green roof on the quantity and quality of rainfall-generated roof runoff. In addition to these small-scale installations, the U.S. Geological Survey’s Ipswich River Basin model was used to simulate the basin-wide effects on streamflow of several changes: broad-scale implementation of LID techniques, reduced water-supply withdrawals, and water-conservation measures. Water-supply and conservation scenarios for application in model simulations were developed with the assistance of two technical advisory committees that included representatives of State agencies responsible for water resources, the U.S. Environmental Protection Agency, the U.S. Geological Survey, water suppliers, and non-governmental organizations. From June 2005 to June 2007, groundwater quality was monitored at the Silver Lake town beach parking lot in Wilmington, Massachusetts, prior to and following the replacement of the conventional, impervious-asphalt surface with a porous surface consisting primarily of porous asphalt and porous pavers designed to enhance rainfall infiltration into the groundwater and to minimize runoff to Silver Lake. Concentrations of phosphorus, nitrogen, cadmium, chromium, copper, lead, nickel, zinc, and total petroleum hydrocarbons in groundwater were monitored. Enhancing infiltration of precipitation did not result in discernible increases in concentrations of these potential groundwater contaminants. Concentrations of dissolved oxygen increased slightly in groundwater profiles following the removal of the impervious asphalt parking-lot surface. In Wilmington, Massachusetts, in a 3-acre neighborhood, stormwater runoff volume and quality were monitored to determine the ability of selected LID enhancements (rain gardens and porous paving stones) to reduce flows and loads of the selected constituents to Silver Lake. Water-quality samples were analyzed for nutrients, metals, total petroleum hydrocarbons, and total-coliform and E. coli bacteria. A decrease in runoff quantity was observed for storms of 0.25 inch or less of precipitation. Water-quality-monitoring results were inconclusive; there were no statistically significant differences in concentrations or loads when the pre- and post-installation-period samples were compared. In a third field study, the characteristics of runoff from a vegetated "green" roof and a conventional, rubber-membrane roof were compared. The two primary factors affecting the green roof’s water-storage capacity were the amount of precipitation and antecedent dry period. Although concentrations of many of the chemicals in roof runoff were higher from the green roof than from the conventional roof, the ability of the green roof to retain water generally resulted in decreased differences between the total amounts (loads) of the chemicals that ran off the roofs. Land-use and water-management changes associated with LID implementation were investigated at multiple spatial scales, using the U.S. Geological Survey’s Ipswich River Basin model, to evaluate the effects of updated water-supply withdrawals for the towns of Reading and Wilmington (representing new baseline conditions for all simulations), potential land-use changes at buildout (potential future development), widespread implementation of retrofitting LID techniques, basin-scale water withdrawal reductions based on water-conservation pilot programs conducted by the Massachusetts Department of Conservation and Recreation, and land-use change and LID applications at a local scale. The new baseline simulation indicated that reduced water-supply withdrawals for the towns of Reading and Wilmington led to substantially higher medium and low flows in most of the reaches upstream from the South Middleton streamgage in the upper Ipswich River basin. Overall, simulations pointed to the importance of spatial scale in determining the effects of land-use change and LID practices on streamflow. Potential land-use changes at buildout had modest effects on streamflow in most subbasins (percent differences of less than 20 percent) because relatively little land in the basin was available for development. Results of the simulations conducted to evaluate widespread effective-impervious-area reductions upstream from the South Middleton streamgage indicated that the percentages of urban land use and associated effective impervious area were too small for even a 50-percent reduction of effective impervious area to appreciably affect streamflow in most subbasins. In contrast, the results of the hypothetical local-scale simulations indicated that for smaller streams, with high percentages of urban land use and associated effective impervious area, land-use change, development patterns, and LID practices may have substantial effects on streamflow. Modeling studies concurred with the results of fieldwork in the assessment that LID enhancements would likely have the greatest effect on decreasing stormwater runoff when broadly applied to highly impervious urban areas.

Massachusetts↗

USGS2012

Crop classification modelling using remote sensing and environmental data in the Greater Platte River Basin, USA

With an ever expanding population, potential climate variability and an increasing demand for agriculture-based alternative fuels, accurate agricultural land-cover classification for specific crops and their spatial distributions are becoming critical to researchers, policymakers, land managers and farmers. It is important to ensure the sustainability of these and other land uses and to quantify the net impacts that certain management practices have on the environment. Although other quality crop classification products are often available, temporal and spatial coverage gaps can create complications for certain regional or time-specific applications. Our goal was to develop a model capable of classifying major crops in the Greater Platte River Basin (GPRB) for the post-2000 era to supplement existing crop classification products. This study identifies annual spatial distributions and area totals of corn, soybeans, wheat and other crops across the GPRB from 2000 to 2009. We developed a regression tree classification model based on 2.5 million training data points derived from the National Agricultural Statistics Service (NASS) Cropland Data Layer (CDL) in relation to a variety of other relevant input environmental variables. The primary input variables included the weekly 250 m US Geological Survey Earth Observing System Moderate Resolution Imaging Spectroradiometer normalized differential vegetation index, average long-term growing season temperature, average long-term growing season precipitation and yearly start of growing season. An overall model accuracy rating of 78% was achieved for a test sample of roughly 215 000 independent points that were withheld from model training. Ten 250 m resolution annual crop classification maps were produced and evaluated for the GPRB region, one for each year from 2000 to 2009. In addition to the model accuracy assessment, our validation focused on spatial distribution and county-level crop area totals in comparison with the NASS CDL and county statistics from the US Department of Agriculture (USDA) Census of Agriculture. The results showed that our model produced crop classification maps that closely resembled the spatial distribution trends observed in the NASS CDL and exhibited a close linear agreement with county-by-county crop area totals from USDA census data ( R 2 = 0.90).

Greater Platte River Basin↗

USGS2007

Mercury accumulation in periphyton of eight river ecosystems

In 2003, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface-sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r2 = 0.88, in log-log space). Mean MeHg and THg concentrations in surface-sediment periphyton were significantly higher (1,333 ng/m2 for MeHg and 53,980 ng/m2 for THg) than cobble (64 ng/m2 for MeHg and 1,192 ng/m2 for THg) or woody snag (71 ng/m2 for MeHg and 1,089 ng/m2 for THg) periphyton. Concentrations of THg in surface-sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface-sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems. ?? 2007 American Water Resources Association.

Journal of the American Water Resources Associatio↗

USGS2008

Land use and the structure of western US stream invertebrate assemblages: Predictive models and ecological traits

Inferences drawn from regional bioassessments could be strengthened by integrating data from different monitoring programs. We combined data from the US Geological Survey National Water-Quality Assessment (NAWQA) program and the US Environmental Protection Agency Wadeable Streams Assessment (WSA) to expand the scope of an existing River InVertebrate Prediction and Classification System (RIVPACS)-type predictive model and to assess the biological condition of streams across the western US in a variety of landuse classes. We used model-derived estimates of taxon-specific probabilities of capture and observed taxon occurrences to identify taxa that were absent from sites where they were predicted to occur (decreasers) and taxa that were present at sites where they were not predicted to occur (increasers). Integration of 87 NAWQA reference sites increased the scope of the existing WSA predictive model to include larger streams and later season sampling. Biological condition at 336 NAWQA test sites was significantly (p < 0.001) associated with basin land use and tended to be lower in basins with intensive landuse modification (e.g., mixed, urban, and agricultural basins) than in basins with relatively undisturbed land use (e.g., forested basins). Of the 437 taxa observed among reference and test sites, 180 (41%) were increasers or decreasers. In general, decreasers had a different set of ecological traits (functional traits or tolerance values) than did increasers. We could predict whether a taxon was a decreaser or an increaser based on just a few traits, e.g., desiccation resistance, timing of larval development, habit, and thermal preference, but we were unable to predict the type of basin land use from trait states present in invertebrate assemblages. Refined characterization of traits might be required before bioassessment data can be used routinely to aid in the diagnoses of the causes of biological impairment. ?? 2008 by The North American Benthological Society.

Arizona, California, Colorado, Idaho, Montana, New↗

USGS2010

National Land Cover Database 2001 (NLCD01) Tree Canopy Layer Tile 1, Northwest United States: CNPY01_1

This 30-meter resolution data set represents the tree canopy layer for the conterminous United States for the 2001 time period. The data have been arranged into four tiles to facilitate timely display and manipulation within a Geographic Information System, browse graphic: nlcd01-partition.jpg. The National Land Cover Data Set for 2001 was produced through a cooperative project conducted by the Multi-Resolution Land Characteristics (MRLC) Consortium. The MRLC Consortium is a partnership of Federal agencies (www.mrlc.gov), consisting of the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental Protection Agency (USEPA), the U.S. Department of Agriculture (USDA), the U.S. Forest Service (USFS), the National Park Service (NPS), the U.S. Fish and Wildlife Service (USFWS), the Bureau of Land Management (BLM), and the USDA Natural Resources Conservation Service (NRCS). One of the primary goals of the project is to generate a current, consistent, seamless, and accurate National Land Cover Database (NLCD) circa 2001 for the United States at medium spatial resolution. For a detailed definition and discussion on MRLC and the NLCD 2001 products, refer to Homer and others (2004) and http://www.mrlc.gov/mrlc2k.asp. The NLCD 2001 was created by partitioning the United States into mapping-zones. A total of 68 mapping-zones browse graphic: nlcd01-mappingzones.jpg were delineated within the conterminous United States based on ecoregion and geographical characteristics, edge-matching features, and the size requirement of Landsat mosaics. Mapping-zones encompass the whole or parts of several states. Questions about the NLCD mapping zones can be directed to the NLCD 2001 Land Cover Mapping Team at the USGS/EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov

Report↗

USGS2010

National Land Cover Database 2001 (NLCD01) Tree Canopy Layer Tile 2, Northeast United States: CNPY01_2

This 30-meter resolution data set represents the tree canopy layer for the conterminous United States for the 2001 time period. The data have been arranged into four tiles to facilitate timely display and manipulation within a Geographic Information System, browse graphic: nlcd01-partition.jpg The National Land Cover Data Set for 2001 was produced through a cooperative project conducted by the Multi-Resolution Land Characteristics (MRLC) Consortium. The MRLC Consortium is a partnership of Federal agencies (www.mrlc.gov), consisting of the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental Protection Agency (USEPA), the U.S. Department of Agriculture (USDA), the U.S. Forest Service (USFS), the National Park Service (NPS), the U.S. Fish and Wildlife Service (USFWS), the Bureau of Land Management (BLM), and the USDA Natural Resources Conservation Service (NRCS). One of the primary goals of the project is to generate a current, consistent, seamless, and accurate National Land Cover Database (NLCD) circa 2001 for the United States at medium spatial resolution. For a detailed definition and discussion on MRLC and the NLCD 2001 products, refer to Homer and others (2004) and http://www.mrlc.gov/mrlc2k.asp. The NLCD 2001 was created by partitioning the United States into mapping-zones. A total of 68 mapping-zones browse graphic: nlcd01-mappingzones.jpg were delineated within the conterminous United States based on ecoregion and geographical characteristics, edge-matching features, and the size requirement of Landsat mosaics. Mapping-zones encompass the whole or parts of several states. Questions about the NLCD mapping zones can be directed to the NLCD 2001 Land Cover Mapping Team at the USGS/EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov.

Report↗