Detailed mapping (1:24,000), measured sections, and clast counts in conglomerates of the Duchesne River Formation and Bishop Conglomerate in the Vernal NW quadrangle in northeastern Utah reveal the middle Cenozoic stratigraphic geometry, the uplift and unroofing history of the eastern Uinta Mountains, and give evidence for the pulsed termination of Laramide uplift. The Unita Mountains are an EW-trending reverse fault bounded and basement-cored, Laramide uplift. The oldest unit of the Duchesne River Formation, the Eocene Brennan Basin Member, contains 80-90% Paleozoic clasts and <20% Precambrian clasts. Proximal to the Uinta uplift the conglomerates of this member are dominated by Paleozoic Madison Limestone clasts (70-90% of all clasts). Farther out into the basin, Paleozoic clasts still dominate in Brennan Basin Member conglomerates, but chert clasts are more abundant (up to 43%) showing the efficiency of erosion of the carbonate clasts over a short distance (~5 km). Conglomerates in the progressively younger Dry Gulch Creek, Lapoint, and Starr Flat members show a significant upward increase in Precambrian clasts with 34-73% Uinta Mountain Group and 8-63% Madison Limestone. Duchesne River Formation has a significant increase in coarse-grained deposits from the southern parts of the quadrangle (20-50% coarse) to the northern parts (75% coarse) nearer the Uinta uplift. The lower part of the Duchesne River Formation exhibits a fining upward sequence representing a tectonic lull. Clast count patterns show that pebbly channel deposits in the south maintain similar compositions to their alluvial fan counterparts. To the north, the fine-grained Lapoint and Dry Gulch Creek members of the Duchesne River Formation appear to pinch out completely. This can be explained by erosion of these fine-grained deposits or by lateral facies shifts before deposition of the next unit. Starr Flat Member conglomerates were deposited above Lapoint Member siltstones and represent southward progradation of alluvial fans away from the uplifting mountain front. Similarities in composition and sedimentary structures have caused confusion surrounding the contact between the Starr Flat Member and the overlying Bishop Conglomerate. Within the Vernal NW quadrangle, we interpret this contact as an angular unconformity (the Gilbert Peak Erosion Surface) developed on the uppermost tilted red siltstone of the Starr Flat Member sometime after 37.9 Ma. Stratigraphic and structural relationships reveal important details about the development of a Laramide mountain range: 1) sequential unroofing sequences in the Duchesne River Formation, 2) progradation of alluvial fans to form the Starr Flat Member, 3) and the unconformable nature of the Gilbert Peak Erosion Surface lead to the conclusion that there were at least 3 distinct episodes of uplift during the deposition of these formations. The last uplift episode upwarped the Starr Flat Member constraining the termination of Laramide uplift in the Uinta Mountains to be after deposition of the Starr Flat Member and prior to deposition of the horizontal Bishop Conglomerate starting at about 34 Ma. This, combined with 40Ar/39Ar ages of 39.4 Ma from the Dry Gulch Creek and Lapoint member, show that slab rollback related volcanism was occurring to the west while the Uinta Mountains were being uplifted on Laramide faults. These new 40Ar/39Ar ages constrain the timing of deposition and clarify stratigraphic relationships within the Duchesne River Formation; they suggest a significant unconformity of as much as 4 m.y. between the Duchesne River Formation and the overlying Bishop Conglomerate, which is 34-30 Ma in age, and show that Laramide uplift continued after 40 Ma in this region.

Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2006. / Geography, Geoinformatics and Meteorology / Unrestricted

The ruffed grouse (Bonasa umbellus incana) inhabits much of the deciduous woodland of northern and central Utah. Its distribution is confined mainly to the Wasatch and Uinta mountain ranges. It has been observed in willows (Salix spp.) at 5, 000 feet elevation and in Douglas-fir (Pseudotsuga menziesii) at 9,000 feet.

The headwaters of the Bear River in the Uinta Mountains of Utah provide a good setting in which to examine the influence of geological materials on stream chemistry. Ionic contributions to the stream-water from soils, vegetation, and the atmosphere generally are sparse enough that they do not mask the geologic contributions. Samples from 37 sites on the four major headwater streams and several minor tributaries were examined geochemically. Data derived from the samples allowed the construction of a hydrogeochemical weathering model specific to the study area. A significant feature of this model is that carbonic acid is the dominant chemical agent involved in geochemical weathering. The aim of this study was to examine the geologic influences on river chemistry. However, atmospheric contributions dominate the hydrochemistry through at least the first 10 kilometers of stream length for the easternmost three of the four major headwater streams. Except for the atmospheric contribution, surface-water chemistry is dominated by the groundwater chemistry, which is indelibly marked by the lithology the groundwater passes through. Other geologic factors in the study area that appear to influence groundwater chemistry, and hence stream chemistry, are the glacial till and outwash deposits and a major zone of east-west trending high-angle thrust faults. A technique for estimating the hydrochemistry of the groundwater based on surface-water chemistry and flow measurements was developed in this study.

A significant question currently facing environmental managers is how to accurately and efficiently quantify forest diversity and resources. Numerous studies have demonstrated the use of modern spatial analytical tools , such as geographical information systems (GIS), remote sensing devices, and statistical models for predicting the distribution of dominant vegetation cover types. This study examines the ability of generalized additive models (GAMs) to delineate structural diversity in forested ecosystems (specifically the Uinta Mountain Range in Utah) using GIS tools and satellite spectral data, and analyzes the effect of including different forms of satellite data in model construction (i.e., Landsat thematic mapper (TM), advanced very high resolution radiometer (AVHRR), and the GAP Analysis TM-classified map). Based on the assumption that vegetation composition, as well as structural diversity, is a function of environmental gradients, temperature, precipitation, elevation, aspect, slope, and geology were included as independent environmental variables. Probability surface maps were generated for presence of forest , presence of lodgepole pine, basal area of forest trees, percent cover of shrubs, and density of snags. The maps were validated using an independent set of field data collected from the Evanston Ranger District within the Uinta Mountain Range . In general, the models tended to underpredict at large numbers and overpredict at locations that were sampled as having no forest cover. The models predicting the presence of forest and lodgepole pine were 88% and 80% accurate, respectively, within the Evanston Ranger District and an average of 62% of the predictions of basal area, shrub cover , and snag density fell within an approximate 15% deviation from the field validation values . The addition of TM spectral data and the GAP Analysis TM-classified data were found to contribute significantly to the models' predictions, with some contribution from AVHRR data. The methods used in this study provide a systematic approach for delineating structural features within forest habitats, thus offering an efficient spatial tool for making management decisions.

The objectives were (1) to relate terrestrial vertebrate responses to the management practices used for lodgepole pine forests within the Barometer Watershed, Mountain View Ranger District, Wasatch National Forest, Utah . (2) To correlate terrestrial vertebrate densities or frequencies with community types, edge, major forest stand structures , and (3) to propose management plans to manipulate densities of major vertebrate species in a predetermined manner. The study was conducted between 1973-1975 and provides a detailed description of forest vegetation for 53 lodgepole pine (Pinus contorta) stands. For each of these stands, a complete summary is provided of tree populations, coverage, and frequency of major vascular undergrowth species . Eight lodgepole pine forest community types are defined. A key is provided for identification of each community type and its anticipated habitat type. The relationships between densities of major vertebrate species, forest communities, and major forest stand structures are described. Big game utilization of ecotones created by mountain meadows and the lodgepole pine forest are discussed. In addition, the response of selected small mammal and big game species to clearcut size is provided. Important research findings were: (1) In the lodgepole pine forest most vertebrates exhibit preferences for specific community types. (2) Due to the broad definition of present habitat classifications, limited predictions can be made about the general response of wildlife populations on most sites. (3) The use of park-like openings and associated peripheral timber hy big game animals is closely associated with community type, edge configuration, and historical travel lanes. (4) An abundance of downed woody material enhances big game calving and resting areas. (S) The number of bird species is closely associated with understory biomass and diversity. (6) Management schemes that speed up the rotation of lodgepole pine overstories eliminate certain vertebrate communities associated with the final successional stages. The following specific recommendations for overstory removal are suggested. (1) Timber sales should be developed by drainage, with longterm objectives that insure the distribution of a variety of communities within a drainage. (2) The addition of major stand structure information should be included in habitat classification systems. (3) Timber sales should be designed with irregular edges and buffers of standing timber which provide cover and concealment. (4) Moist sites and relic areas, representing the final stages of succession, should be planned into the overall drainage sale philosophy. {5) In relatively undisturbed areas, vehicular travel should be prohibited following overstory removal.

The Shiras moose, Alces alces shirasi, and its winter habitat on the north slopes of the Uinta Mountains in Utah were studied from August, 1969, to July, 1971 to determine the food requirement for moose, the key browse species during the winter months, the acreage, density and utilization of the key browse species, and their carrying capacity for moose. It was determined that an average adult moose had a daily food requirement of 19,133 kilocalories. The key browse species for moose were Salix drummondiana and S. geyeriana. These two species accounted for 92.0 and 4.7 percent respectively of all feeding occurrences on browse species recorded. According to density analyses, S. drummondiana made up 59 percent of the vegetation and S. geyeriana 31 percent. The caloric capacity of the key browse species for moose body maintenance was slightly more than 1.5 billion kilocalories. The moose carrying capacity of the key browse species on the winter range was 80,030 moose days or 445 adult animals for a period of six months. Specifically, the carrying capacity, based on a weighted caloric requirement and annual classification counts, would be 115 bulls, 250 cows, and 156 calves for a period of six months on the winter range.

New glacial mapping and 35 cosmogenic 36Cl surface exposure ages, the first ever reported from Alaska , constrain the extent and timing of late Pleistocene glacial fluctuations in the western Ahklun Mountain s, southwe stern Alaska. Morphometric and soil relativeage data characterize two main drift units deposited during the Arolik Lake and Klak Creek glaciations , named herein. During the Arolik Lake glaciation (early Wisconsin), outlet glaciers emanated from an ice cap over the central portion of the Ahklun Mountains and deposited moraines at or beyond the modern coast. These moraines have slope angles averaging about 11° and crests averaging about 35 m wide . Four moraine boulders deposited during this glaciation have a weighted mean surface exposure age of 53.6 ± 2.0 36Cl ka. During the Klak Creek glaciation (late Wisconsin), ice-cap outlet glaciers deposited moraines 20-80 km up-valley from Arolik Lake moraines. Valley glaciers expanded from high massifs that fringe the major river valleys in the western Ahklun Mountains and terminated independently from the relatively restricted ice-cap outlet glaciers. Moraines deposited during the Klak Creek glaciation have steeper slopes (mean = -18°) and sharper crests (mean= about 17 m) than do Arolik Lake moraines. Twenty-eight 36Cl ages were obtained from six Klak Creek moraines from three valleys and reveal two phases of glaciation during the late Wisconsin, one from about 25 to 23 36Cl ka, and another from 19 to 15 36Cl ka. An ice-cap outlet glacier moraine underlies a valley glacier terminal moraine, both of which have ages of 18-19 36Cl ka, and indicates that the ice-cap outlet glacier had retreated from its maximum position shortly before the valley glacier reached its maximum position. Equilibrium-line altitudes (ELAs) for reconstructed Klak Creek valley glaciers average about 400 m, which is only about 200 m below the estimated modem altitude. The restricted extent of Klak Creek glaciers might reflect a lack of available moisture as sea ice covered the Bering Sea during the peak of the last global glacial maximum. When compared to the marine oxygen-isotope record, the timing of glacier advances in the western Ahklun Mountains indicates that glaciers responded to both regional and global climate changes.

The organization and morphology of Middle Fork Sheep Creek and South Fork Sheep Creek, two mountain streams in the upper Sheep Creek basin, are controlled by the spatial distribution of glacial moraines. Both channels are organized into a reoccurring sequence of steep-gradient reaches changing downstream to low-gradient reaches. Steep-gradient reaches are located where the channels flow through moraine s. Low-gradient reaches are located in meadows downstream of the steep-gradient reaches and immediately upstream of the next moraine. Knickpoints in the longitudinal profiles of both streams coincide with the location of moraines. Large boulder s, beyond the size transportable by the channel at bankfull discharge, are found within the steep-gradient channels, and are presumed to be glacial lag. Between knickpoints, channel morphology follows the conceptual model of Montgomery and Buffington. Unlike mountain channels elsewhere, landslides, debris flows, and alluvial fans do not influence the morphology or organization of Middle Fork Sheep Creek and South Fork Sheep Creek. Large woody debris loading is less than on channels in Washington and Alaska, with debris dams found mainly in reaches with gradients less than cascade and greater than pool-riffle. Middle Fork Sheep Creek and South Fork Sheep Creek are located in a glaciated basin. At time scales of 103 to 104 years, the channels may be classified as in disequilibrium and the system is not adjusted to present conditions. The presence of large, unmovable boulder s within the steep-gradient channels allows the location of the steep-gradient channels to remain static until the large particles are transported during infrequent large discharges. At time scales of 101 to 102 years, the channels may be thought of as equilibrium systems with channel variables adjusted to the present climate.

Mule deer (Odocoileus hemionus) reproduction and survival on the LaSal Mountains, Utah were studied from 1978-81. Reproductive rates were high, suggesting that summer and fall forage quality was adequate and was not responsible for low recruitment observed in recent years. The combined fetal rate, determined from laparotomies and carcasses, was 1.72 for all females older than 1 year (N = 114). Fetal rates were 1.15 for yearlings (N = 20), 1.80 for prime females (2-7 years, N = 78), and 1.75 for old females (8+ years, N = 16). No evidence of breeding was found among fawns (N = 18). Estimated intrauterine mortality was 3.9%. A compensatory response to inadequate winter nutrition was not identified as a factor in maintaining high reproductive potentials, although its role might have been obscured by the high predation rate on young fawns. During 1979 and 1980, an average of 67% of the total annual loss of radio-monitored fawns occurred within 54 days postpartum. Survival of transmittered fawns (N = 54) from capture to December averaged 42.7%. Direct causes of mortality during the summer included predation (73%}, primarily by coyotes (Canis latrans} and black bears (Ursus americanus}; starvation, accidents, and illegal kills (9%}; and unknown factors (18%}. Overwinter survival of fawns and does was inversely related to winter intensity. Fawn survival from January to June was 58.3% of the December population in 1980 and 88.9% in 1981. During this period, predation or probable predation, primarily by coyotes, accounted for 82% of the observed deaths and accidents for 18%. Substantial losses to malnutrition and domestic dogs occurred in Castle Valley during the severe winter of 1978-79. Total annual survival of transmittered fawns was similar both years, 28.9% for the 1979 cohort and 31.8% for the 1980 cohort. Application of a change-in-ratio estimator yielded estimates of fawn survival that were similar to survival rates from samples of radio-monitored fawns, except during summer 1979 when prenatal and immediate postpartum mortality may have been high following the severe 1978-79 winter. Annual survival rates of radio-monitored does were 68.9% in 1979 (N = 38) and 86.6% (N = 22) in 1980. Causes of death included malnutrition and predation by coyotes and domestic dogs. No mortality occurred among radio-monitored females (N = 32} between January and June 1981. Recruitment rates, estimated from spring fawn proportions were 15% in 1979, 18% in 1980, and 32% in 1981, suggesting herd declines in the first 2 years and herd growth in 1981.