Publications

Since late 1993, the Metro Wastewater Reclamation District of Denver (Metro District), a large wastewater treatment plant in Denver, Colorado, has applied Grade I, Class B biosolids to about 52,000 acres of nonirrigated farmland and rangeland near Deer Trail, Colorado (U.S.A.). In cooperation with the Metro District in 1993, the U.S. Geological Survey (USGS) began monitoring ground water at part o

Several fundamental but important factors controlling the feedback of boreal organic carbon (OC) to climate change were examined using a mechanistic model of soil OC dynamics, including the combined effects of temperature and moisture on the decomposition of OC and the factors controlling carbon quality and decomposition with depth. To estimate decomposition rates and evaluate their variations wit

In March 2008, we collected gravity data along 12 traverses across newly-mapped faults in the Moapa Valley region of Clark County, Nevada. In areas crossed by these faults, the traverses provide better definition of the gravity field and, thus, the density structure, than prior gravity observations. Access problems prohibited complete gravity coverage along all of the planned gravity traverses, an

Cenozoic basins in eastern Nevada and western Utah constitute major ground-water recharge areas in the eastern part of the Great Basin, and our continuing studies are intended to characterize the geologic framework of the region. Prior to these investigations, regional gravity coverage was variable over the region, adequate in some areas and very sparse in others. The current study in Nevada provi

In 2004, the U.S. Geological Survey (USGS), the Geological Survey of Canada (GSC), and the Mexican Geological Survey (Servicio Geologico Mexicano, or SGM) initiated pilot studies in preparation for a soil geochemical survey of North America called the Geochemical Landscapes Project. The purpose of this project is to provide a better understanding of the variability in chemical composition of soil

Two‐dimensional inversion of audiomagnetotelluric (AMT) sounding data define buried resistivity distributions that reflect subsurface geology and structure within the upper kilometer beneath Pleasant Valley, a 1–2 km‐deep pull‐apart basin in Joshua Tree National Park, southern California. The Park lies within the Eastern California Shear Zone just east of the San Andreas Fault, and is surrounded b

Water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans. On alluvial fans where water transport of gravel predominates, channel slopes tend to decrease downfan from ~0.10–0.04 to ~0.01 across wide ranges of climate and tectonism. Some have argued that this pattern reflects grain-size fining downfan such that higher threshold slopes are required just to ent

The general location and age of more than 33,500 mostly foraminifer samples from Chevron surface localities in nearly 600 U.S. Geological Survey (USGS) 7.5' quadrangles from California were provided by Brabb and Parker (2003). Barren and non-diagnostic samples plus many that have no paleontologic information were omitted to provide a revised list for more than 27,000 of these samples by Brabb and

One-dimensional burial and thermal history modeling of the Yukon Flats basin, east-central Alaska, was conducted as part of an assessment of the region’s undiscovered oil and gas resources. No deep exploratory wells have been drilled in the Yukon Flats region, and the subsurface geology of the basin is inferred from seismic reflection, gravity and magnetic surveys, and studies of shallow core hole

The U.S. Geological Survey (USGS) has completed an assessment of undiscovered conventional oil and gas resources in all areas north of the Arctic Circle. Using a geology-based probabilistic methodology, the USGS estimated the occurrence of undiscovered oil and gas in 33 geologic provinces thought to be prospective for petroleum. The sum of the mean estimates for each province indicates that 90 bil

Discovery of a 3-foot thick sandstone bed with abundant Turritellid gastropods of late Paleocene age about 4 miles northeast of Fairfield and on the southwest flank of Cement Hill, Solano County provides an opportunity to reevaluate the relationships of lower Tertiary formations in this part of California. Cement Hill is named for travertine deposits in and on top of sandstone of Late Cretaceous a