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Research about Boulder, Fort Collins, Greeley, Colorado

Source-linked reports with geographic coverage including Boulder, Fort Collins, Greeley, Colorado.

4 recordsLinked to original sources
USGS2003

A spatial database of bedding attitudes to accompany Geologic Map of Boulder-Fort Collins-Greeley area, Colorado

This digital map shows bedding attitude data displayed over the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 (U.S.Geological Survey Map I-855-G) under the Front Range Urban Corridor Geology Program. Colton used his own mapping and published geologic maps having varied map unit schemes to compile one map with a uniform classification of geologic units. The resulting published color paper map was intended for planning for use of land in the Front Range Urban Corridor. In 1997-1999, under the USGS Front Range Infrastructure Resources Project, Colton's map was digitized to provide data at 1:100,000 scale to address urban growth issues(see cross-reference). In general, the west part of the map shows a variety of Precambrian igneous and metamorphic rocks, major faults and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The eastern and central part of the map (Colorado Piedmont) depicts a mantle of Quaternary unconsolidated deposits and interspersed Cretaceous or Tertiary-Cretaceous sedimentary rock outcrops. The Quaternary mantle is comprised of eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone and shale formations (and sparse limestone) form hogbacks, intervening valleys, and in range-front folds, anticlines, and fault blocks. Localized dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

Colorado↗
USGS1983

Shallow ground water in the Boulder-Fort Collins-Greeley area, Front Range urban corridor, Colorado, 1975-77

Shallow ground water may limit the location of construction and excavation projects in parts of the Front Range Urban Corridor. A shallow water table occurs from 0 to 50 feet below the land surface principally in the alluvial deposits along the streams and rivers in the Boulder-Fort Collins-Greeley area. This shallow water table underlies approximately 400 square miles and is maintained by natural recharge within the South Platte River basin and by the infiltration of irrigation water that is diverted into the basin from streams and reservoirs in the Colorado and the Laramie River basins. Return flow from irrigation, which is mostly ground water, helps maintain the flow of the South Platte River and its tributaries. The report includes a map from which depth to water table and the direction of ground-water movement can be determined. The map, compiled on a topographic base, shows the areal extent of the saturated materials and the altitude and configuration of the ground-water surface. The water-table contour map was prepared using data from approximately 400 wells. Monitoring of shallow ground-water within the study area shows depths to water have changed only slightly over the last 20 years, except for some seasonal and drought-related fluctuations. Gradients, computed from ground-water measurements, range from 27.7 feet per mile in Lone Tree-Spring Creek valley to 10.3 feet per mile in the South Platte River valley. The shallow ground-water underflow from the major tributaries in the basin is about 29,000 acre-feet per year, and underflow calculated at a cross section near Kersey is about 12,000 acre-feet per year.

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USGS1978

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 (GIS). That product is described here. In general, the digitized map depicts in its western part Precambrian igneous and metamorphic rocks, Pennsylvanian and younger sedimentary rock units, major faults, and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The central and eastern parts of the map (Colorado Piedmont) show a mantle of Quaternary unconsolidated deposits and interspersed outcrops of sedimentary rock of Cretaceous or Tertiary age. A surficial mantle of unconsolidated deposits of Quaternary age is differentiated and depicted as eolium (wind-blown sand and silt), alluvium (river gravel, sand, and silt of variable composition), colluvium, and a few landslide deposits. At the mountain front, north-trending, Paleozoic and Mesozoic formations of sandstone, shale, and minor limestone dip mostly eastward and form folds, fault blocks, hogbacks and intervening valleys. Local dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

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