USGS Science⌕ Search

Geology topics

Research about Colorado

Source-linked reports with geographic coverage including Colorado.

At least 1,477 records · Page 82Linked to original sources
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.

Colorado↗
USGS1983

Distribution and origin of sulfur in Colorado oil shale

The sulfur content of 1,225 samples of Green River oil shale from two core holes in the Piceance Creek Basin, Colorado, ranges from nearly 0 to 4.9 weight percent. In one core hole, the average sulfur content of a sequence of oil shale 555 m thick, which represents nearly the maximum thickness of oil shale in the basin, is 0.76 weight percent. The vertical distribution of sulfur through the oil shale is cyclic. As many as 25 sulfur cycles have lateral continuity and can be traced between the core holes. Most of the sulfur resides in iron sulfides (pyrite, marcasite, and minor? pyrrhotite), and small amounts are organically bound in kerogen. In general, the concentration of sulfur correlates moderately with shale-oil yield, but the degree of association ranges from quite high in the upper 90 m of the oil -shale sequence to low or none in the leached zone and in illitic oil shale in the lower part of the sequence. Sulfur also correlates moderately with iron in the carbonate oil -shale sequence, but no correlation was found in the illitic samples. Sulfide mineralization is believed to have occurred during early and late stages of diagenesis, and after lithification, during development of the leached zone. Significant amounts of iron found in ankeritic dolomite and in illite probably account for the lack of a strong correlation between sulfur and iron.

Colorado↗
USGS1982

DDT poisoning in a Cooper's hawk collected in 1980

In April 1980, a Cooper's hawk ( Accipiter cooperii ) was found on the ground in Lakewood, Colorado, unable to fly and in convulsion. The bird died shortly thereafter. The hawk was packed in dry ice and shipped air express to the Fish and Wildlife Service, U. S. Department of the Interior, National Wildlife Health Laboratory, Madison, Wisconsin, for necropsy. Following necropsy, the brain, gastrointestinal tract, and remaining carcass except skin, feet, wings, liver, and kidney were packed in dry ice and shipped air express to the Patuxent Wildlife Research Center, Laurel, Maryland, for chemical residue analysis. Because the bird's behavior before death suggested some form of poisoning, the kidney was assayed for thallium, the liver for lead, and the gastrointestinal tract for strychnine, sodium fluoroacetate, and arsenic. When these assays proved negative, the bird was analyzed for organochlorine pesticides. Necropsy findings and pesticide residue analyses are reported here.

Colorado↗
USGS1982

Geochemical and geostatistical evaluation, Arkansas Canyon Planning Unit, Fremont and Custer Counties, Colorado

A mineral assessment of the Arkansas Canyon Planning Unit was undertaken by Barringer Resources Inc., under the terms of contract YA-553-CTO-100 with the Bureau of Land Management, Colorado State Office. The study was based on a geochemical-geostatistical survey in which 700 stream sediment samples were collected and analyzed for 25 elements. Geochemical results were interpreted by statistical processing which included factor, discriminant, multiple regression and characteristic analysis. The major deposit types evaluated were massive sulfide-base metal, sedimentary and magmatic uranium, thorium vein, magmatic segregation, and carbonatite related deposits. Results of the single element data and multivariate geostatistical analysis indicate that limited potential exists for base metal mineralization near the Horseshoe, El Plomo, and Green Mountain Mines. Thirty areas are considered to be anomalous with regard to one or more of the geochemical parameters evaluated during this study. The evaluation of carbonatite related mineralization was restricted due to the lack of geochemical data specific to this environment.

Colorado↗
USGS1981

Role of solute-transport models in the analysis of groundwater salinity problems in agricultural areas

Undesirable salinity increases occur in both groundwater and surface water and are commonly related to agricultural practices. Groundwater recharge from precipitation or irrigation will transport and disperse residual salts concentrated by evapotranspiration, salts leached from soil and aquifer materials, as well as some dissolved fertilizers and pesticides. Where stream salinity is affected by agricultural practices, the increases in salt load usually are attributable mostly to a groundwater component of flow. Thus, efforts to predict, manage, or control stream salinity increases should consider the role of groundwater in salt transport. Two examples of groundwater salinity problems in Colorado, U.S.A., illustrate that a model which simulates accurately the transport and dispersion of solutes in flowing groundwater can be (1) a valuable investigative tool to help understand the processes and parameters controlling the movement and fate of the salt, and (2) a valuable management tool for predicting responses and optimizing the development and use of the total water resource.

Colorado↗
USGS1981

Geologic structure, hydrology, and water quality of the Laramie-Fox Hills aquifer in the Denver basin, Colorado

The Denver ground-water basin underlies a 6,700-square-mile area extending from Greeley in the north to Colorado Springs in the south, and from the Front Range in the west to near Limon in the east. The four major bedrock aquifers that occur in the basin are the Laramie-Fox Hills aquifer (the deepest aquifer), the Arapahoe aquifer, the Denver aquifer, and the Dawson aquifer (the uppermost aquifer). The Laramie-Fox Hills aquifer, which is the subject of this report, underlies the entire area of the basin in east-central Colorado (index map, fig. 1) and is an important source of water for residents in the northern Denver suburban area and in the rural areas of eastern Jefferson, Arapahoe, and Elbert Counties, Adams County, and southern Weld and El Paso Counties. About 90 percent of the estimated 1,700 wells completed in the aquifer supply water to residents and livestock. The remaining wells supply water for commercial and industrial use and limited irrigation of commercial crops.

Colorado↗