Geology topics
Research about Colorado
Source-linked reports with geographic coverage including Colorado.
Geologic and coal outcrop map of the Weston quadrangle, Las Animas County, Colorado
No abstract available.
Water-level records for the northern High Plains of Colorado
Water-level measurements were made in 665 wells in January 1979 in the northern High Plains of Colorado. Measurements for January 1979 and the four preceding winters are given in a table.
Gravity, magnetic, and seismic studies of the Silver Cliff and Rosita Hills volcanic area, Colorado
No abstract available.
Altitude and configuration of the water table and depth to water in the northern High Plains of Colorado, January 1978
No abstract available.
Quantity and quality of urban runoff from three localities in the Denver Metropolitan area, Colorado
Considerable variation in constituent concentrations was shown in urban runoff data for 1975-77 from three metropolitan Denver drainage basins. Constituent concentrations, greatest during initial rainfall runoff, generally peaked midday of snowmelt runoff, corresponding with maximum melting and runoff. Instantaneous loads of constituents were largely a function of discharge. Days since last street sweeping or antecedent precipitation had no apparent effect; snowmelt-runoff loads apparently increased with number of days snow had been on the ground. Urban storm runoff may significantly contribute total ammonia nitrogen, total nonfiltrable residue, total copper, total iron, total lead, and total zinc; and snowmelt runoff may significantly contribute sodium and chloride, to local receiving waters. Data from two basins were used for calibration and verification of U.S. Environmental Protection Agency's Storm Water Management Model II for rainfall-runoff modeling of flow and total nitrogen. The model assumption that land-surface loads of total nitrogen are directly proportional to number of days prior to storm during which accumulated rainfall was less than 1.0 inch was not substantiated. (Woodard-USGS)
Effects of grazing on runoff and sediment yield from desert rangeland at Badger Wash in western Colorado, 1953-73
No abstract available.
Effects of converting sagebrush cover to grass on the hydrology of small watersheds at Boco Mountain, Colorado
Changes in runoff and sediment yield caused by changing sagebrush cover to grass cover were studied at four small watersheds in western Colorado during a 9-year period, from 1965 to 1978. Measurements of runoff and sediment yield from the four watersheds were made for 8 years, at which time two watersheds were plowed and seeded to beardless bluebunch wheatgrass. The same measurements were then continued for an additional 6 years. Measurements indicated that conversion to grass caused a reduction in runoff from summer rainstorms of about 75 percent. Runoff from spring snowmelt increased about 12 percent, and annual runoff from treated watersheds decreased about 20 percent when compared to control watersheds. Sediment yield from the seeded watersheds was reduced by about 80 percent; most of this reduction is related to the decrease in runoff from summer rainstorms. The size of barren interspaces between plants was reduced on the converted water- sheds to about 30 percent of those on the untreated watersheds. Linear regression analysis indicates that a reduction of 38 percent in the amount of bare soil resulting from planting grass would result in a decrease of 73 percent in sediment concentration.
Geologic map of the Fort Logan quadrangle, Jefferson, Denver, and Arapahoe Counties, Colorado
No abstract available.
Hydrology of the Arapahoe aquifer in the Englewood-Castle Rock area south of Denver, Denver basin, Colorado
No abstract available.
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.
Landslides in the Front Range Urban Corridor, Colorado
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Reconnaissance map showing relative amounts of soil and bedrock in the mountainous part of the Boulder Quadrangle, Boulder County, Colorado
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Reconnaissance map showing relative amounts of soil and bedrock in the mountainous part of the Horsetooth Reservoir Quadrangle, Larimer County, Colorado
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