Person

Joseph P Colgan

Research Geologist

Geosciences and Environmental Change Science Center

Email: jcolgan@usgs.gov
Office Phone: 303-236-1021
Fax: 303-236-5601
ORCID: 0000-0001-6671-1436

Supervisor: Harland L Goldstein

15 items:

Surface and subsurface geologic data from previous USGS studies of the Gulf Coast region, south-central United States This dataset captures in digital form the results of previously published U.S. Geological Survey (USGS) Water Mission Area studies related to water resource assessment of Cenozoic strata and unconsolidated deposits within the Mississippi Embayment and the Gulf Coastal Plain of the south-central United States. The data are from reports published from the late 1980s to the mid-1990s by the Gulf Coast Regional Aquifer-System Analysis (RASA) studies and in 2008 by the Mississippi Embayment Regional Aquifer Study (MERAS). These studies, and the data presented here, describe the geologic and hydrogeologic units of the Mississippi embayment, Texas coastal uplands, and the coastal lowlands aquifer systems, south-central... Tags: 3D, Alabama, Arkansas, Cane River Formation, Carrizo Sand, All tags...
Digital database of the previously published geologic map of the greater Denver area, Front Range Urban Corridor, Colorado This digital map shows the areal extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette from 1973 to 1977 and published in 1979 under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999)... Tags: Adams County, Arapahoe County, Arapahoe Formation, Colorado, Colorado Front Range, All tags...
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic mapping in and around those districts, whereas much of that for samples from the Goldfield district were obtained by Ashley (1974; 1979; 1990). Additional data were derived from samples collected between 2012–2017, as part of the U.S. Geological Survey Mineral Resources Program funded project titled: “Magmatic-tectonic history... Categories: Data; Tags: Ar, Divide mining district, Economic Geology, Esmeralda County, Fraction Tuff, All tags...
Digital database of the previously published geologic map of the Boulder-Fort Collins-Greeley area, Colorado This digital map shows the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 under the Front Range Urban Corridor Geology Program. Colton used his own geologic mapping and previously published geologic maps to compile one map having a single classification of geologic units. The resulting published color paper map (USGS Map I-855-G, Colton, 1978) was intended for land-use planning and to depict the regional geology. In 1997-1999, another USGS project designed to address urban growth issues was undertaken. This project, the USGS Front Range Infrastructure Resources Project, undertook to digitize Colton's map at 1:100,000 scale, making it useable in Geographical Information Systems... Tags: Boulder, Boulder County, Boulder Creek granodiorite, Colorado, Colorado Front Range, All tags...
Digital database of the previously published geologic map of the O'Neill 1x2 degree quadrangle, Nebraska This digital data release contains geospatial data for the geologic map of the O’Neill 1 degree by 2 degree geologic map in Nebraska, originally published in 2008 by R.E. Diffendal and others. The original map consists of a 1:250,000 scale map plate with a “stack unit” structure showing multiple overlying units, as well as several roughly 1:750,000 scale maps in an accompanying pamphlet showing bedrock geology and structure contours. To capture as much of this content as possible in a geodatabase, three “layers” are included in this database: 1) Overlay polygons showing Quaternary loess deposits (Qes) where they overlay older Quaternary units; 2) a layer (consisting of line and polygon feature classes) showing Quaternary... Categories: Data; Tags: Cretaceous, GeMS, Geologic Map Schema, Hydrology, NCGMP, All tags...

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