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At least 19 recordsLinked to original sources
USGS1954

The gold pan: A neglected geological tool

The gold pan is ordinarily regarded as a tool for sampling placer deposits. Another and very important application is shown to be the sampling and study of decomposed bedrock, in regions where outcrops of hardrock are scarce or lacking. This technique was proposed and used by Derby, an American geologist who worked for many years in Brazil. The importance of this method has not been generally recognized, and the writer recalls it to the attention of geologists. An important application is shown to exist in the study of the decomposed bedrock, known as saprolite, that is so widespread in the Piedmont province of the southeastern United States. Using this technique, two projects have already been successfully completed in this region, and the success attained in both sets a new standard for geological exploration and mapping in areas where saprolite constitutes the dominant type of exposure. The technique of panning for heavy and semiheavy accessory minerals is described. Types of pans, factors in panning, the operation of panning, and the processing of concentrates in the field are briefly discussed. The gold pan, in the hands of an experienced operator, is shown to be a versatile and efficient field tool, which is completely independent of laboratory facilities. © 1954 Society of Economic Geologists, Inc.

Economic Geology↗
USGS1957

Report and recommendations on surface water resources investigation in Turkey

Turkey is in a state of transition from an agricultural and pastoral economy to an economy that combines agriculture and industry. Such a transition includes use of water resources for water power, irrigation, manufacturing, and domestic uses. The control of streams for multiple purposes invariably leads to conflicts of interest. Several Turkish streams rise in or flow into other countries. For these reasons, data on the flow of streams over a fairly long period of time are needed in order to plan the most beneficial use and control of the streams of Turkey. This report deals largely with the collection of surface water data. The need for data on suspended sediment is considered briefly. In some areas of Turkey ground-water resources are now being studied by a team of Turkish and American geologists and engineers.

Report↗
USGS1969

Physiographic, stratigraphic, and structural development of the Quadrilatero Ferrifero, Minas Gerais, Brazil

The Quadrilatero Ferrifero is an area of some 7,000 square kilometers in central Minas Gerais, Brazil centered about lat. 20°15' S, long. 43°30' W. For 250 years the region has poured forth a variety of mineral riches, now totaling more than $2 billion, and future production will undoubtedly be even greater. The main products are iron ore, manganese ore, and gold. To assist this development, the Braziliam and American Governments in 1946 jointly undertook the first detailed geologic study of the region: this report is a synthesis of the results of work and mapping by 17 Brazilian and American geologists under this program; other reports discussing the economic geology, the metamorphic geology, and the igneous geology of the region as a whole are being prepared.

Minas Gerais↗
USGS2014

Activities in tectonics of Research Committee of American Association of Petroleum Geologists

During 1945 and 1946, the Research Committee of the American Association of Petroleum Geologists, under the chairmanship of Shepard W. Lowman, has been engaged in “a reconnaissance survey of research in petroleum geology and allied sciences with explicit reference to exploration” in order “to formulate a comprehensive research program which the American Association of Petroleum Geologists may adopt as its recommendation for that research most needed to improve our ability to find oil” [see “References” at end of report, Lowman, 1945]. In order to make this survey, the field was divided among a number of subcommittees, including a Subcommittee on Tectonics, of which the writer was chairman. Preliminary reports, discussing the research possibilities in the various fields covered by the subcommittees, were submitted in January, 1946, and concrete recommendations were formulated by the Research Committee at the Chicago meeting of the Association in April 1946 [Lowman, 1946]. Final reports of the subcommittees will be published later in 1946 in the Bulletin of the American Association of Petroleum Geologists.

Eos, Transactions, American Geophysical Union↗
USGS2012

Geology of the Devonian Marcellus Shale--Valley and Ridge province, Virginia and West Virginia--a field trip guidebook for the American Association of Petroleum Geologists Eastern Section Meeting, September 28-29, 2011

Detailed and reconnaissance field mapping and the results of geochemical and mineralogical analyses of outcrop samples indicate that the Devonian shales of the Broadtop Synclinorium from central Virginia to southern Pennsylvania have an organic content sufficiently high and a thermal maturity sufficiently moderate to be considered for a shale gas play. The organically rich Middle Devonian Marcellus Shale is present throughout most of the synclinorium, being absent only where it has been eroded from the crests of anticlines. Geochemical analyses of outcrop and well samples indicate that hydrocarbons have been generated and expelled from the kerogen originally in place in the shale. The mineralogical characteristics of the Marcellus Shale samples from the Broadtop Synclinorium are slightly different from the averages of samples from New York, Pennsylvania, northeast Ohio, and northern West Virginia. The Middle Devonian shale interval is moderately to heavily fractured in all areas, but in some areas substantial fault shearing has removed a regular "cleat" system of fractures. Conventional anticlinal gas fields in the study area that are productive from the Lower Devonian Oriskany Sandstone suggest that a continuous shale gas system may be in place within the Marcellus Shale interval at least in a portion of the synclinorium. Third-order intraformational deformation is evident within the Marcellus shale exposures. Correlations between outcrops and geophysical logs from exploration wells nearby will be examined by field trip attendees.

Virginia;West Virginia↗
USGS2007

Divisions of geologic time—Major chronostratigraphic and geochronologic units

Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and calibrated in years. Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales. Since the mid-1990s, geologists from the U.S. Geological Survey (USGS), State geological surveys, academia, and other organizations have sought a consistent time scale to be used in communicating ages of geologic units in the United States. Many international debates have occurred over names and boundaries of units, and various time scales have been used by the geoscience community. For consistency purposes, the USGS Geologic Names Committee and the Association of American State Geologists developed Divisions of Geologic Time .

Fact Sheet↗
USGS2018

Divisions of geologic time—Major chronostratigraphic and geochronologic units

Introduction Effective communication in the geosciences requires a consistent nomenclature for stratigraphic units and, especially, for divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years. Geologists from the U.S. Geological Survey (USGS), State geological surveys, academia, and other organizations require a consistent time scale to be used in communicating ages of geo­logic units in the United States. Many international debates have occurred over names and boundaries of units, and various time scales have been used by the geoscience community. For consistent usage of time terms, the USGS Geologic Names Committee and the Association of American State Geologists devel­oped the Divisions of Geologic Time ; the 2018 update in this fact sheet contains the unit names and boundary age estimates ratified by the International Commission on Stratigraphy in 2018. Scientists may use other published time scales, provided that these are specified and referenced.

Fact Sheet↗
USGS1999

Surficial sediments along the inner continental shelf of Maine

Through 10 years of support from the Minerals Management Service Association of American State Geologists' Continental Margins Program we have mapped along the Maine coast, seaward to the 100 m isobath. In all, 1,773 bottom sample stations were occupied, 3,358 km of side-scan sonar and 5,011 km of seismic reflection profiles were gathered. On the basis of these data, a surficial sediment map was created for the Maine inner continental shelf during the Year 8 project, and cores and seismic data were collected to evaluate sand thickness during Years 9 and 10. Sand covers only 8 % of the Maine shelf , and is concentrated seaward of beaches off southern Maine in water depths less than 60 m. Sand occurs in three depositional settings: (1) in shoreface deposits connected dynamically to contemporary beaches; (2) in submerged deltas associated with lower sea-level positions; and (3) in submerged lowstand shoreline positions between 50 and 60 m. Seismic profiles over the shoreface off Saco Bay, Wells Embayment, and off the Kennebec River mouth each imaged a wedge-shaped acoustic unit which tapered off between 20 and 30 m. Cores determined that this was sand that was underlain by a variable but thin (commonly 1 m) deposit of estuarine muddy sand and a thick deposit of glacial-marine mud. Off Saco Bay, more than 55 million m3 of sand exists in the shoreface, compared with about 22 million m3 on the adjacent beach and dunes. Seaward of the Kennebec River, a large delta deposited between 13 ka and the present time holds more than 300 million m3 of sand and gravel. The best sorted sand is on the surface nearshore, with increasing amounts of gravel offshore and mud beneath the surficial sand sheet. Bedforms indicate that the surficial sand is moved by waves to at least 55 m depth. Seaward of the Penobscot River, no significant sand or gravel was encountered. Muddy estuarine sediments overlie muddy glacial-marine sediment throughout the area offshore area of this river. No satisfactory explanation is offered for lack of a sandy delta seaward of Maine's largest river. Lowstand-shoreline deposits were cored in many places in Saco Bay and off the Kennebec River mouth. Datable materials from cores indicated that the lowstand occurred around 10.5 ka off the Kennebec. Cores did not penetrate glacial-marine sediment in the lowstand deposits , and seismic profiles were ambiguous about the vertical extent of sand in these units. For these reasons, no total thickness of sand was determined from the lowstand deposits , but given the area of the surficial sand, the volume is probably in the hundreds of millions of cubic meters.

Maine↗
USGS1999

Stratigraphic framework and heavy minerals of the continental shelf of Onslow and Long Bays, North Carolina

One hundred fourteen vibracores from the Atlantic continental shelf offshore of southeastern North Carolina were opened, described, and processed over several contract years (years 6-9) of the Minerals Management Service-Association of American State Geologists Continental Margins program. Reports for years 9 and 10 of the program compiled the results of the work and assembled the data for release as an interactive CD-ROM report, respectively. The continental shelf of Onslow and Long Bays consists predominantly of outcropping Cretaceous through late Tertiary geologic units. Nearshore these units are covered and incised by late Tertiary and Quaternary units. From oldest to youngest, formally recognized geologic units mapped as part of this study are the Late Cretaceous Peedee Formation-a muddy, fine- to medium-grained quartz sand with trace amounts of glauconite and phosphate; the Paleocene Beaufort Formation-a muddy, fine- to medium-grained glauconitic quartz sand with locally occurring turritelid-mold biosparrudite; the middle Eocene Castle Hayne Formation-a sandy bryozoan biomicrudite and biosparrudite; the Oligocene River Bend Formation-a sandy molluscan-mold biosparrudite; and the Miocene Pungo River Formation-a medium-grained, poorly sorted slightly shelly phosphatic sand. Informal units include a very widespread, unnamed fine- to very fine grained, well-sorted, dolomitic muddy quartz sand that is biostratigraphically equivalent to the Oligocene River Bend Formation; several large valley-fill lithosomes composed of biomicrudite, biomicrite, and biosparrudite of Plio/Pleistocene age; muddy, shelly sands and silty clays of Pliocene, Pleistocene, or mixed Plio/Pleistocene age; and loose, slightly shelly, medium- to coarse-grained sands assigned a Holocene age. Heavy minerals (SG > 2.96) comprise an average of 0.54 wt% (on a bulk-sample basis) of the sediments in 306 samples derived from the 114 vibracores. Heavy-mineral content ranges from <0.01 to 3.69 wt%. The economic heavy mineral content (EHM = ilmenite + zircon + rutile + aluminosilicates + leucoxene [altered ilmenite] + monazite) of the bulk samples averages 0.26 wt% in a range of <0.01-1.70 wt%. As a percentage of the heavy-mineral concentrate, the average EHM value is 45.78% in a range of 0.27-68.60%. The distribution of heavy minerals offshore of southeastern North Carolina is controlled by the lithostratigraphic framework. The unnamed Oligocene sand unit has the highest heavy-mineral content, averaging 0.86 wt% on a bulk-sample basis. The remaining geologic units and their heavy-mineral content (in decreasing order of abundance) are Beaufort (0.64%), Holocene sand (0.60%), Plio-Pleistocene muddy sand and silty clay (0.59%), Peedee (0.42%), River Bend (0.34%), Plio-Pleistocene carbonate (0.12%), and Castle Hayne (0.08%). The heavy-mineral assemblage is fairly consistent throughout the different units. Significantly smaller percentages of heavy minerals correlate with increased amounts of CaCO 3 in the sediments. The sediments analyzed in this study have significantly lower overall heavy-mineral content, as well as lower EHM content than sediments that are known to host commercially important heavy-mineral deposits in the southeastern United States. The potential for economic deposits of heavy minerals in the area of this study, therefore, appears to be limited.

Marine Georesources and Geotechnology↗
USGS2019

The Earth Mapping Resources Initiative (Earth MRI): Mapping the Nation’s critical mineral resources

The Earth Mapping Resources Initiative (Earth MRI; formerly known as 3DEEP) is planned as a partnership between the U.S. Geological Survey (USGS), the Association of American State Geologists (AASG), and other Federal, State, and private-sector organizations. The goal of the effort is to improve our knowledge of the geologic framework in the United States and to identify areas that have the potential to contain undiscovered critical mineral resources. Enhancement of our domestic mineral supply will decrease our reliance on foreign sources of minerals that are fundamental to the Nation’s security and economy. The intent of Earth MRI is to leverage the USGS’s existing relationships with States and the private sector to conduct state-of-the-art geologic mapping and airborne geophysical and topographic (lidar) surveys. Analyses of these datasets could point to potential buried critical mineral deposits.

Fact Sheet↗
USGS2019

U.S. Geological Survey EDMAP Program—Training the next generation of geologic mappers

Detailed geologic maps are the basis of nearly every Earth-science investigation and can be used for natural hazard mitigation, resource identification and exploration, infrastructure planning, and more. A component of the congressionally mandated National Cooperative Geologic Mapping Program, EDMAP is a partnership among the U.S. Geological Survey, the Association of American State Geologists, and participating colleges and universities that provides mentorship and training opportunities to geology students nationwide. Under the guidance of a faculty member, EDMAP supports upper level undergraduate and graduate students to gain meaningful experience working on 1-year geologic-mapping projects. Between 1996 and 2019, EDMAP funded research projects for more than 1,200 students at more than 160 universities. Every Federal dollar awarded through the EDMAP program is matched by the student’s university.

Fact Sheet↗
USGS2023

National map of focus areas for potential critical mineral resources in the United States

Introduction The U.S. Geological Survey (USGS) launched the Earth Mapping Resources Initiative (Earth MRI) to modernize the surface and subsurface geologic mapping of the United States, with a focus on identifying areas that may have the potential to contain critical mineral resources. EarthMRI can inform strategies to ensure secure and reliable domestic critical mineral supplies for the United States as mandated by Executive Order 13817 and the Infrastructure and Jobs Act of 2021 (Public Law 117–58, 135 Stat. 529). Earth MRI is a collaborative effort between the USGS and the State geological surveys as represented by the Association of American State Geologists to identify, prioritize, and acquire new geoscience data for geographic areas, or focus areas, across the Nation that have potential to host critical mineral resources. Mapping of focus areas was based on a framework of mineral systems and their associated mineral deposit types that could possibly host critical minerals. Using readily available geologic, geophysical, geochemical, and mineral deposit data, teams of USGS scientists worked with representatives of State geological surveys in a series of workshops to outline focus areas that contain evidence of key features for one or more mineral systems. These areas can be used to guide future efforts to collect new geologic, geophysical, geochemical, and topographic data that focus on critical minerals through Earth MRI.

Fact Sheet↗
USGS2002

Digital mapping techniques '02, workshop proceedings : May 19-22, 2002, Salt Lake City, Utah

The Digital Mapping Techniques '02 (DMT'02) workshop was attended by 101 technical experts from 43 agencies, universities, and private companies, including representatives from 25 state geological surveys (see Appendix A). This workshop was similar in nature to the previous five meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998a), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), and in Tuscaloosa, Alabama (Soller, 2001). This year's meeting was hosted by the Utah Geological Survey, from May 19 to 22, 2002, on the University of Utah campus in Salt Lake City. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. When an attendee adopts or modifies a newly learned technique on the basis of discussions at the workshop, 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). All the DMT workshops have been coordinated by the Association of American State Geologists (AASG) and the U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996 to support the AASG 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 for the database--and the State and Federal geological surveys--to provide more high-quality digital maps to the public. At the 2002 meeting, oral and poster presentations and special discussion sessions emphasized (1) methods for creating and publishing map products (here, "publishing" includes Web-based release); (2) techniques for scanning already published maps and managing and delivering them on the Web; (3) continued development of the National Geologic Map Database; and (4) progress toward building a standard geologic map data model. In addition, special presentations were provided on building a statewide GIS council, incorporating geology as a NSDI Framework layer, and resolving the roles of surveyors and GIS professionals.

Open-File Report↗
USGS2003

Digital mapping techniques '03 - Workshop proceedings

The Digital Mapping Techniques '03 (DMT'03) workshop was attended by nearly 90 technical experts from 36 agencies, universities, and private companies, including representatives from 22 state geological surveys (see Appendix A). Although the meeting was slightly smaller than DMT'02 it was, considering the budget deficits in nearly all 50 states, very well attended. This workshop was similar in nature to the previous six meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), in Tuscaloosa, Alabama (Soller, 2001), and in Salt Lake City, Utah (Soller, 2002). This year's meeting was hosted by the Pennsylvania Geological Survey, from June 1-4, 2003, on the Millersville University campus in Millersville, Pennsylvania. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. This objective was well met, as attendees continued to share and exchange knowledge and information, and to renew friendships and collegial work begun at past DMT workshops. All the DMT workshops have been coordinated by the Association of American State Geologists (AASG) and U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996, to support the AASG 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 for the database— and the State and Federal geological surveys—to provide more high-quality digital maps to the public. At the 2003 meeting, oral and poster presentations and special discussion sessions emphasized 1) methods for creating and publishing map products (here, "publishing" includes Web-based release); 2) digital cartographic techniques, 3) analytical GIS techniques; 4) continued development of the National Geologic Map Database; 5) progress toward building and implementing a standard geologic map data model and standard science language, and 6) the need to archive both the published products and the data and observational data that support it.

Open-File Report↗
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↗
USGS2004

Digital mapping techniques '04, workshop proceedings : May 16-19, 2004, Portland, Oregon

The Digital Mapping Techniques ‘04 (DMT’04) workshop was attended by about 100 technical experts from 40 agencies, universities, and private companies, including representatives from 22 state geological surveys (see Appendix A). This workshop was similar in nature to the previous seven meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), in Tuscaloosa, Alabama (Soller, 2001), in Salt Lake City, Utah (Soller, 2002), and in Millersville, Pennsylvania (Soller, 2003). This year’s meeting was hosted by the Oregon Department of Geology and Mineral Industries, from May 16–19, 2004, on the Portland State University campus in Portland, Oregon. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. This objective was well met, as attendees continued to share and exchange knowledge and information, and to renew friendships and collegial work begun at past DMT workshops. All the DMT workshops have been coordinated by the Association of American State Geologists (AASG) and U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996, to support the AASG and the USGS in their effort to build a National Geologic Map Database (see Soller, Berg, and Stamm, this volume, and http://ngmdb.usgs.gov/info/standards/datacapt/ ). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed for the National database—and for the State and Federal geological surveys—to provide more high-quality digital maps to the public. At the 2004 meeting, oral and poster presentations and special discussion sessions emphasized: 1) methods for creating and publishing map products (here, “publishing” includes Web-based release); 2) field data capture software and techniques; 3) digital cartographic techniques; 4) migration of digital maps into ArcGIS Geodatabase format; 5) analytical GIS techniques; 6) continued development of the National Geologic Map Database; and 7) progress toward building and implementing a standard geologic map data model and standard science language for the U.S. and for North America.

Open-File Report↗