Publications

Prognostic vegetation models have been widely used to study the interactions between environmental change and biological systems. This study examines the sensitivity of vegetation model simulations to: (i) the selection of input climatologies representing different time periods and their associated atmospheric CO2 concentrations, (ii) the choice of observed vegetation data for evaluating...

Gravity and aeromagnetic data refine the structural setting for the region of western Utah and eastern Nevada between Snake and Hamlin Valleys on the west and Tule Valley on the east. These data are used here as part of a regional analysis. An isostatic gravity map shows large areas underlain by gravity lows, the most prominent of which is a large semi-circular low associated with the...

To assess the eff ect of pedogenesis on the soil moisture dynamics infl uencing the character and quality of ecological habitat, we conducted infi ltration and redistribution experiments on three alluvial deposits in the Mojave National Preserve: (i) recently deposited active wash sediments, (ii) a soil of early Holocene age, and (iii) a highly developed soil of late Pleistocene age. At...

We present a discussion on the limitations and needed improvements for existing slope stability analysis methods to accurately model steep coastal bluff failures resulting from both direct wave action at the toe in weakly cemented sands and precipitation-induced seepage failures in moderately cemented sands. Using a case-study detailing over 5 years of observations of coastal bluff...

In northwest Arizona, the relatively unextended Colorado Plateau gives way abruptly to the highly extended Colorado River extensional corridor within the Basin and Range province along a system of major west-dipping normal faults, including the Grand Wash fault zone and South Virgin–White Hills detachment fault. Large growth-fault basins developed in the hanging walls of these faults...

Recently, the potential for terrestrial carbon (C) sequestration by soil erosion and deposition has received increased interest. Erosion and deposition constitute a sink for atmospheric carbon dioxide relative to a preerosional state or a noneroding scenario, if the posterosion watershed C balance is increased due to (1) partial replacement of eroded C by new photosynthate in the eroded...

Temporal data from five springs in the Cement Creek watershed, San Juan County, Colorado provide seasonal geochemical data for further research in the formation of ferricretes. In addition, these data can be used to help understand the ground-water flow system. The resulting data demonstrate the difficulty in gathering reliable seasonal data from springs, show the unique geochemistry of...

Meter-size granite basins are found in a 180-km belt extending south from the South Fork of the Kings River to Lake Isabella on the west slope of the southern Sierra Nevada, California. Their origin has long been debated. A total of 1,033 basins have been inventoried at 221 sites. The basins occur on bedrock granitic outcrops at a median elevation of 1,950 m. Median basin diameter among...

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...

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...

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...

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...