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At least 343 records · Page 19Linked to original sources
USGS2002

Fourth international circumpolar arctic vegetation mapping workshop

During the week of April 10, 2001, the Fourth International Circumpolar Arctic Vegetation Mapping Workshop was held in Moscow, Russia. The purpose of this meeting was to bring together the vegetation scientists working on the Circumpolar Arctic Vegetation Map (CAVM) to (1) review the progress of current mapping activities, (2) discuss and agree upon a standard set of arctic tundra subzones, (3) plan for the production and dissemination of a draft map, and (4) begin work on a legend for the final map.

Open-File Report↗
USGS2003

Generalized lithology and lithogeochemical character of near-surface bedrock in the New England region

This geographic information system (GIS) data layer shows the dominant lithology and geochemical, termed lithogeochemical, character of near-surface bedrock in the New England region covering the states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. The bedrock units in the map are generalized into groups based on their lithological composition and, for granites, geochemistry. Geologic provinces are defined as time-stratigraphic groups that share common features of age of formation, geologic setting, tectonic history, and lithology. This data set incorporates data from digital maps of two NAWQA study areas, the New England Coastal Basin (NECB) and the Connecticut, Housatonic, and Thames River Basins (CONN) areas and extends data to cover the states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. The result is a regional dataset for the lithogeochemical characterization of New England (the layer named NE_LITH). Polygons in the final coverage are attributed according to state, drainage area, geologic province, general rock type, lithogeochemical characteristics, and specific bedrock map unit.

Connecticut, Maine, Massachusetts, New Hampshire, ↗
USGS2000

Digital mapping techniques '00, workshop proceedings - May 17-20, 2000, Lexington, Kentucky

Introduction: The Digital Mapping Techniques '00 (DMT'00) workshop was attended by 99 technical experts from 42 agencies, universities, and private companies, including representatives from 28 state geological surveys (see Appendix A). This workshop was similar in nature to the first three meetings, held in June, 1997, in Lawrence, Kansas (Soller, 1997), in May, 1998, in Champaign, Illinois (Soller, 1998a), and in May, 1999, in Madison, Wisconsin (Soller, 1999). This year's meeting was hosted by the Kentucky Geological Survey, from May 17 to 20, 2000, on the University of Kentucky campus in Lexington. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. When, based on discussions at the workshop, an attendee adopts or modifies a newly learned technique, the workshop clearly has met that objective. Evidence of learning and cooperation among participating agencies continued to be a highlight of the DMT workshops (see example in Soller, 1998b, and various papers in this volume). The meeting's general goal was to help move the state geological surveys and the USGS toward development of more cost-effective, flexible, and useful systems for digital mapping and geographic information systems (GIS) analysis. Through oral and poster presentations and special discussion sessions, emphasis was given to: 1) methods for creating and publishing map products (here, 'publishing' includes Web-based release); 2) continued development of the National Geologic Map Database; 3) progress toward building a standard geologic map data model; 4) field data-collection systems; and 5) map citation and authorship guidelines. Four representatives of the GIS hardware and software vendor community were invited to participate. The four annual DMT workshops were coordinated by the AASG/USGS Data Capture Working Group, which was formed in August, 1996, to support the Association of American State Geologists and the USGS in their effort to build a National Geologic Map Database (see Soller and Berg, this volume, and http://ncgmp.usgs.gov/ngmdbproject/standards/datacapt/). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed to help the Database, and the State and Federal geological surveys, provide more high-quality digital maps to the public.

Open-File Report↗
USGS2008

Geologic map of Mount St. Helens, Washington prior to the 1980 eruption

It is rare that a geologic map exists for a volcano prior to such a catastrophic modification as that produced by the eruption of Mount St. Helens in 1980. As such, this map provides an important historical record of the volcano prior to that eruption. The map has not been reviewed or checked for conformity to USGS editorial standards or stratigraphic nomenclature, and it has not been digitized. This version of the map is unchanged from that submitted to the USGS for publication shortly after the 1980 eruption of Mount St. Helens and includes unresolved inconsistencies with the subsequently published work of Crandell (1987) and Mullineaux (1996). Nevertheless, it is the most accurate available depiction of the pre-1980 edifice and is published here for comparison with more recent geologic mapping and historical perspectives.

Open-File Report↗
USGS2004

Surficial materials in the conterminous United States

Introduction: The Earth's bedrock is overlain in many places by a loosely compacted and mostly unconsolidated blanket of sediments in which soils commonly are developed. These sediments generally were eroded from underlying rock, and then were transported and deposited. In places, they exceed 1,000 ft (330 m) in thickness. Where the sediment blanket is absent, bedrock is either exposed or has been weathered to produce a residual soil. This map shows the sediments and the weathered, residual material; for ease of discussion, these are referred to here as 'surficial materials.' Certain areas on this map include a significant number of rock outcrops, which cannot be shown at the scale of the map; this is noted in the 'Description of Map Units' section. Most daily human activities occur on or near the Earth's surface. Homeowners, communities, and governments can make improved decisions about hazard, resource, and environmental issues, when they understand the nature of surficial materials and how they vary from place to place. For example, are the surficial materials upon which a home is built stable enough to resist subsidence or lateral movement during an earthquake? Do these materials support a ground water resource adequate for new homes? Can they adequately filter contaminants and protect buried aquifers both in underlying sediments and in bedrock? Are they suitable for development of a new wetland? Where can we find materials suitable for aggregate? The USGS National Cooperative Geologic Mapping Program (NCGMP) works with the State geological surveys to identify priority areas for mapping of surficial materials (for example, in areas of complex and poorly understood deposits of various sediment types, where metropolitan areas are experiencing rapid growth). To help establish these priorities, a modern, synoptic overview of the geology is needed. This map represents an overview of our current knowledge of the composition and distribution of surficial materials in the conterminous United States. (The map covers only the conterminous U.S. because similar geologic information in digital form was not readily available for Alaska and Hawaii.) The best available map has been a highly generalized depiction at 1:7,500,000-scale (about 120 miles to the inch), prepared for the USGS National Atlas (Hunt, 1979; 1986). This map is compiled at a slightly more detailed scale (about 80 miles to the inch) than Hunt (1979; 1986). We used digital methods, which enabled us to rapidly incorporate the variety of source maps available to us. State-scale geologic maps from the western United States were brought directly into this map, without expending the time needed to resolve interpretive differences among them. Therefore, abrupt changes in surficial materials are indicated along many State boundaries. This of course is an artifact of our compilation technique, and a limitation on its utility. However, this approach supports the basic premise of the map -- to provide an overview of surficial materials, and to identify areas where additional work may be needed in order to resolve scientific issues that can, in turn, lead to improved mapping.

Open-File Report↗
USGS2007

Antarctica and global paleogeography: from Rodinia, rhrough Gondwanaland and Pangea, to the birth of the Southern Ocean and the opening of gateways

Neoproterozoic Rodinia reconstructions associate East Antarctica (EANT) with cratonic Western Australia. By further linking EANT to both Gondwana and Pangea with relative plate circuits, a Synthetic Apparent Polar Wander (SAPW) path for EANT is calculated. This path predicts that EANT was located at tropical to subtropical southerly latitudes from ca. 1 Ga to 420 Ma. Around 400 Ma and again at 320 Ma, EANT underwent southward drift. Ca. 250 Ma Antarctica voyaged briefly north but headed south again ca. 200 Ma. Since 75 Ma EANT became surrounded by spreading centers and has remained extremely stable. Although paleomagnetic data of the blocks that embrace West Antarctica are sparse, we attempt to model their complex kinematics since the Mesozoic. Together with the SAPW path and a revised circum-Antarctic seafloor spreading history we construct a series of new paleogeographic maps.

Open-File Report↗
USGS2007

Scoping of Flood Hazard Mapping Needs for Hancock County, Maine

Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine Floodplain Management Program (MFMP) State Planning Office, began scoping work in 2006 for Hancock County. Scoping activities included assembling existing data and map needs information for communities in Hancock County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) database with information gathered during the scoping process. The average age of the FEMA floodplain maps (all types) in Hancock County, Maine, is at least 19 years. Most of these studies were published in the late 1980s and early 1990s, and no study is more recent than 1992. Some towns have partial maps that are more recent than their study, indicating that the true average age of the data is probably more than 19 years. Since the studies were done, development has occurred in some of the watersheds and the characteristics of the watersheds have changed. Therefore, many of the older studies may not depict current conditions or accurately estimate risk in terms of flood heights or flood mapping.

Open-File Report↗
USGS2007

Scoping of Flood Hazard Mapping Needs for Penobscot County, Maine

Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine State Planning Office Floodplain Management Program (MFMP), began scoping work in 2006 for Penobscot County. Scoping activities included assembling existing data and map needs information for communities in Penobscot County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) Database with information gathered during the scoping process. As of 2007, the average age of the FEMA floodplain maps in Penobscot County, Maine, is 22 years, based on the most recent revisions to the maps. Because the revisions did not affect all the map panels in each town, however, the true average date probably is more than 22 years. Many of the studies were published in the mid-1980s. Since the studies were completed, development has occurred in many of the watersheds, and the characteristics of the watersheds have changed with time. Therefore, many of the older studies may not depict current conditions nor accurately estimate risk in terms of flood heights or flood mapping.

Open-File Report↗
USGS2007

Scoping of Flood Hazard Mapping Needs for Lincoln County, Maine

Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine Floodplain Management Program (MFMP) State Planning Office, began scoping work in 2006 for Lincoln County. Scoping activities included assembling existing data and map needs information for communities in Lincoln County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) database with information gathered during the scoping process. The average age of the FEMA floodplain maps in Lincoln County, Maine is at least 17 years. Many of these studies were published in the mid- to late-1980s, and some towns have partial maps that are more recent than their study. However, in the ensuing 15-20 years, development has occurred in many of the watersheds, and the characteristics of the watersheds have changed with time. Therefore, many of the older studies may not depict current conditions nor accurately estimate risk in terms of flood heights or flood mapping.

Open-File Report↗
USGS2007

Scoping of Flood Hazard Mapping Needs for Androscoggin County, Maine

Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed and as funds allow. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine Floodplain Management Program (MFMP) State Planning Office, began scoping work in 2006 for Androscoggin County. Scoping activities included assembling existing data and map needs information for communities in Androscoggin County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) Database with information gathered during the scoping process. The average age of the FEMA floodplain maps in Androscoggin County, Maine, is at least 17 years. Most studies were published in the early 1990s, and some towns have partial maps that are more recent than their study date. Since the studies were done, development has occurred in many of the watersheds and the characteristics of the watersheds have changed with time. Therefore, many of the older studies may not depict current conditions nor accurately estimate risk in terms of flood heights or flood mapping.

Open-File Report↗
USGS2008

Chemical Analyses of Pre-Holocene Rocks from Medicine Lake Volcano and Vicinity, Northern California

Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene rocks collected at and near Medicine Lake Volcano, northern California. The data include major-element X-ray fluorescence (XRF) analyses for all of the rocks plus XRF trace element data for most samples, and instrumental neutron activation analysis (INAA) trace element data for many samples. In addition, a limited number of analyses of Na2O and K2O by flame photometry (FP) are included as well assome wet chemical analyses of FeO, H2O+/-, and CO2. Latitude and longitude location information is provided for all samples. This data set is intended to accompany the geologic map of Medicine Lake Volcano (Donnelly-Nolan, in press); map unit designations are given for each sample collected from the map area.

Open-File Report↗
USGS2009

Geologic Criteria for the Assessment of Sedimentary Exhalative (Sedex) Zn-Pb-Ag Deposits

Sedex deposits account for more than 50 percent of the world's zinc and lead reserves and furnish more than 25 percent of the world's production of these two metals. This report draws on previous syntheses as well as on topical studies of deposits in sedex basins to determine the characteristics and processes that produced sedex deposits. This analysis also uses studies of the tectonic, sedimentary, and fluid evolution of modern and ancient sedimentary basins and mass balance constraints to identify the hydrothermal processes that are required to produce sedex deposits. This report demonstrates how a genetic model can be translated into geologic criteria that can be used in the U.S. Geological Survey National Assessments for sedex zinc-lead-silver deposits to define permissive tracts, assess the relative prospectivity of permissive tracts, and map favorability within permissive tracts.

Open-File Report↗