This study is the geochemical examination of mineral weathering and its path from hinterland, through sediment deposition and pedogenesis, to its dissolution and eventual uptake into plants or precipitation as carbonate minerals. The three papers examine the rate and character of carbonate and silicate mineral weathering over a wide range of climatic and tectonic regimes, time periods, and lithologies, and focus on very different questions. Examination of the 87Sr/86Sr ratios of architectural ponderosa pine in Chaco Canyon, New Mexico confirms a societally complex style of timber procurement from the 10th to the 12th centuries. In El Malpais National Monument, New Mexico, we measured the 87Sr/86Sr ratios in local bedrock and soils and compared them to the leaf/wood cellulose of four conifers (Pinus ponderosa, Pinus edulis, Juniperus monosperma, Juniperus scopulorum), a deciduous tree (Populus tremuloides), three shrubs (Chrysothamus nauseosus, Fallugia paradoxa, Rhus trilobata), and an annual grass (Bouteloua gracilis) and a lichen (Xanthoparmelia lineola). We found that plant 87Sr/86Sr ratios covaried with variations in plant physiognomy, life history, and rooting depth. In addition, the proportion of atmospheric dust and bedrock mineral contributions to soil water 87Sr/86Sr ratios varied predictably with landscape age and bedrock lithology. On the Himalayan floodplain, soils and paleosol silicate weathering intensities were measured along a climatic transect and through time. Overall, carbonate weathering dominates floodplain weathering. But, periods of more intense silicate weathering between 9 - 2 Ma, identified in soil profile and in the 87Sr/86Sr ratios of pedogenic carbonates, appear to be driven by changes in tectonic, rather than climatic, regime. All three papers are good examples of how 87Sr/86Sr isotopic tracer studies can shed light on pedogenic formation rates and internal processes. The complexity of each system warns against generalizations based on just one locale, one species or lithology, or a few isotopic ratios.

The debris-flow initiation variable of clay mineralogy is examined for Holocene age debris-flow deposits across the Colorado Plateau. A Kolmogorov-Smirnov two-sample test between 25 debris-flow producing shale units and 23 shale units rated as not producing debris-flows found a highly significant difference between shale unit kaolinite-illite and montmorillonite clay content. Debris-flow producers tend to have abundant kaolinite and illite (61.5% of clays) and small amounts of montmorillonite (10.4%). Clay sample soluble cation (Na, Ca, K, and Mg) content could not be used to accurately divide the data set into debris-flow producers and debris-flow non-producers by either cluster analysis or a Kolmogorov-Smirnov two-sample test.AVIRIS hyperspectral data reveal that debris-flow deposits, colluvium, and some shale units in Cataract Canyon, Utah display the double-absorption feature characteristic of kaolinite at 2.2 µm. Lab-based reflection spectra and semi-quantitative x-ray diffraction results show that Cataract Canyon debris-flow matrix clays are dominated by kaolinite and illite and lacking in montmorillonite. A surface material map showing the spectral stratigraphy of the study area was created from AVIRIS data classified using an artificial neural network and compares favorably to existing geologic data for Cataract Canyon. A debris-flow initiation potential map created from a GIS-based analysis of surface materials, slope steepness, slope aspect, and fault maps shows the greatest debris-flow initiation potential in the study area to coincide with outcrops of the Moenkopi Formation on steep (>20%), southwest-facing slopes. Small areas of extreme debris-flow initiation potential are located where kaolinite and illite clay-rich colluvial wedges are located on southwest-facing walls of Colorado River tributary canyons. The surface materials map shows formations clearly when they remain relatively consistent in composition and exposure throughout the study area, such as the White Rim Sandstone and most clay-rich members of the Moenkopi Formation. The debris-flow producing Organ Rock Shale and Halgaito Formation were shown inconsistently on the surface materials map, likely as a result of compositional variations in the study area. The results of this study provides evidence that hyperspectral imagery classified using an ANN can be successfully used to map the spectral stratigraphy of a sparsely vegetated area such as Cataract Canyon.

Understanding the internal organization of the Lower Pleistocene 8 Sand reservoir in the Green Canyon 18 field, Gulf of Mexico, helps to increase knowledge of the geology and the petrophysical properties, and hence contribute to production management in the area. Interpretation of log data from 29 wells, core and production data served to detail as much as possible a geological model destined for a future reservoir simulation. Core data showed that the main facies resulting from fine-grained turbidity currents is composed of alternating sand and shale layers, whose extension is assumed to be large. They correspond to levee and overbank deposits that are usually associated to channel systems. The high porosity values, coming from unconsolidated sediment, were associated to high horizontal permeability but generally low kv/kh ratio. The location of channel deposits was not obvious but thickness maps suggested that two main systems, with a northwest-southeast direction, contributed to the 8 Sand formation deposition. These two systems were not active at the same time and one of them was probably eroded by overlying formations. Spatial relationships between them remained unclear. Shingled stacking of the channel deposits resulted from lateral migration of narrow, meandering leveed channels in the mid part of the turbidite system. Then salt tectonics tilted turbidite deposits and led to the actual structure of the reservoir. The sedimentary analysis allowed the discrimination of three facies A, B and E, with given porosity and permeability values, that corresponded to channel, levee and overbank deposits. They were used to populate the reservoir model. Well correlation helped figure out the extension of these facies.

In this study the former mining town and present ski resort of Alta, Utah, and the Little Cottonwood Canyon (in which Alta is located) are treated as one unit of study. After a brief treatment of the natural setting, man's earliest activities in the region are traced through the winter of 1966. Activities which are examined include: exploring, trapping, logging, grazing, milling with the major emphasis upon quarrying, mining, skiing and settlement. Until 1864 the region was utilized for non-mining activities. By the 1870's, mining "boomed" and various settlements were established in the canyon. The most famous of these was Alta. Although not formally chartered, Alta was typical of frontier mining camps. Following the decline of mining, the area lay somewhat dormant until the advent of organized skiing in 1937. Now Alta's wealth is found in the snow that falls upon surrounding mountains and not in the silver that was mined from them.

Exposure to ultraviolet radiation (UV) results in both damaging and beneficial health outcomes. Excessive UV exposure has been linked to many skin and eye problems, but moderate exposure induces vitamin D production. It has been reported that humans receive 90-95% of their vitamin D from production that starts after UV exposure. Although it is possible to acquire vitamin D through dietary supplementation, the average person receives very little in this manner. Therefore, since most people acquire their vitamin D from synthesis after exposure to UV from sunlight, it is very important to understand the different environments in which people encounter UV. This project measured UV radiation and in-vitro vitamin D production in the urban canyon and at a nearby suburban location. The urban canyon is an environment consisting of tall buildings and tropospheric air pollution, which have an attenuating effect on UV. Typically, UV measurements are collected in areas outside the urban canyon, meaning that at times studies and public recommendations do not accurately represent the amount of UV reaching street-level in highly urbanized areas. Understanding of UV exposure in urban canyons becomes increasingly important as the number of people working and living in large cities steadily increases worldwide. This study was conducted in the central business district (CBD) of Brisbane, Australia, which models the urban canyons of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers, meaning that most areas only see a small amount of direct sunlight each day. During the winter of 2007 measurements of UV radiation and in-vitro vitamin D production were collected in the CBD and at a suburban site approximately 2.5km outside the CBD. Air pollution data was obtained from a central CBD measurement site. Data analysis showed that urban canyon measurements of both UV radiation and in-vitro vitamin D production were significantly lower than those collected at the suburban site. These results will aid both future researchers and policy makers in better understanding human UV exposure in Brisbane’s CBD and other urban canyons around the world.

Thesis (M.S. - Civil Engineering and Engineering Mechanics)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--Texas State University-San Marcos, 2008. / Vita. Appendices: leaves 87-105. Includes bibliographical references (leaves 106-118). Also available on microfilm.

Thesis (M. S.)--Stanford University, 1998. / Maps and cross-section on 2 folded leaves in pocket. Submitted to the Department of Geological and Environmental Sciences. Copyright by the author.

Thesis (M.A.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Nov. 5, 2008). Includes bibliographical references.