No description available.

No description available.

Call number: LD2668 .R4 1966 G3

No description available.

The density, diversity, and nest-site selection of riparian breeding birds were studied from 1982 to 1985 in mesquite (Prosopis glandulosa) and tamarisk (Tamarix chinensis) communites along the Colorado River in northern Arizona. Avian density in tamarisk communities was significantly greater (P=0.052 and 0.024 in 1984 and 1985, respectively) than avian density in native mesquite communities with similar vegetative cover and height attributes. Avian diversity was similar in both communities. Breeding bird densities in tamarisk were higher than those reported from other geographic areas. Vegetation structure and shrub species composition were measured at nest sites of eleven species of riparian birds in a tamarisk community to examine avian habitat relationships. Riparian birds exhibited differences in their choice of nesting habitat. Discriminant analysis indicated that Bell's Vireo (Vireo bellii), Yellow Warbler (Dendroica petechia) and Yellow-breasted Chat (Icteria virens) were relative generalists in nest site selection, while Common Yellowthroat (Geothlypis trichas) and Northern Oriole (Icterus galbula) were relative habitat specialists. Bell's Vireo and American Coot (Fulica americana) nested in habitats that were the most different. Willow Flycatcher (Empidonax traillii) and Yellow Warbler nested in habitats that were the most similar. Willow Flycatcher and Yellow Warbler consistently used habitat most similar to that used by all other species. Nest placement preferences of six riparian passerines were examined in the tamarisk community to test the null hypothesis that nest placement in any given species of shrub was random. Ninety-five of 105 nests sampled were located in tamarisk. Five of the six species of passerines exhibited a significant preference for tamarisk for nest placement. A highly significant preference for tamarisk was shown by the four species with the smallest median frequency of tamarisk in their nesting habitat. The usefulness of tamarisk for nest placement was higher than that reported from other areas.

The major goal is to reveal the need to understand the dynamics and impacts of landscape change from a current temporal perspective. This is performed here through the study of various settings in the landscape along Highways 180 and 64/180 in Arizona, being proposed for State Scenic Road designation. Selected landscape segments is the subject and the highways are a flexible platform from which to observe and assess these landscapes. Once sources, kinds of, and magnitude of possible or potential landscape changes and impacts are identified, this study proceeds to prescribe landscape planning strategies for their scenic and open space protection and enhancement. Potential landscape change and its impact should be predicted in order to plan and manage for the protection and enhancement of desired landscape values into the future. It can input people's perceptions to appreciate landscape values from varied perspectives such as: aesthetic, ecological, cultural, and socioeconomic.

A field study of positive inversion is conducted to describe associated structural fabrics and to infer kinematic development of the Palisades Monocline, Grand Canyon, Arizona. These features are then compared to sand, clay and solid rock models of positive inversion to test model results and improve understanding of inversion processes. The N40W 90 oriented Palisades fault underlying the monocline has experienced northeast-southwest Precambrian extension and subsequent northeastsouthwest Laramide contraction. The magnitude of inversion is estimated to be 25% based on vertical offset across the fault, although this does not account for flexure or horizontal shortening. The preferred N50W 90 joint and vein orientation and N50W 68 NE and SW conjugate normal faults are consistent with the Palisades fault and northeastsouthwest extension. The N45E 90 joint orientation and approximately N40W 28 NE and SW conjugate thrust faults are consistent with northeast-southwest contraction. The deformation is characterized by three domains across the fault zone: 1) the hanging wall, 2) the footwall, and 3) an interior, fault-bounded zone between the hanging wall and footwall. Extensional features are preserved and dominate the hanging wall, contractional features define footwall deformation, and the interior, fault-bounded zone is marked by the co-existence of extensional and contractional features. Extension caused a master normal fault and hanging wall roll-over with distributed joints, veinsand normal faults. During inversion, contraction induced reverse reactivation of existing hanging wall faults, footwall folding and footwall thrust-faulting. Precambrian normal slip along the master normal fault and subsequent Laramide reverse slip along the new footwall bounding fault created an uplifted domain of relatively oldest strata between the hanging wall and footwall. Physical models of co-axial inversion suggest consistent development of the three domains of deformation described at the Palisades fault, however the models often require magnitudes of inversion greater than 50%. Although vertical block motion during horizontal compression is not predicted directly by the Mohr-Coulomb criterion, physical models and analytical solutions (incorporating Mohr- Coulomb criterion) suggest maximum stress trajectories and near vertical failure above high angle basement faults that compare favorably with the Palisades fault zone.

Thesis (M.S. - Watershed Management)--University of Arizona, 1974. / Includes bibliographical references (leaves 169-171).

Rocks provide insight into ancient times before complex animals existed. The oldest sedimentary rocks in Grand Canyon (the Bass Formation) allow us to glimpse into what things might have been like over a billion years ago. These rocks record the time known as the Mesoproterozoic Era (1.6 to 1.0 billion years ago), otherwise known as the ‘boring billion’. These rocks are thought to be the right age to indicate the end of an oddly stable world when continents were quiet and life was calm, yet they predate younger rocks that record extreme events. The Bass Formation, some of the only rock of this age in the world, contains evidence for life and the carbon cycle, and yields information about Earth’s environments 1.2 billion years ago. The carbon cycle can be studied using carbonate rocks. Assuming that the rock has the same chemistry as the water it formed in, we can measure the relative abundance of carbon isotopes to see a ‘fingerprint’ of the system during the time the rock was deposited. During the boring billion, it is thought that very little variation occurs in this fingerprint. However, as more studies are completed, we see a modest variation in units around the age of the Bass Formation. The fingerprint results from this study can be added to the growing collection of Mesoproterozoic studies and help to further our knowledge about the world from this not-so-boring period of time.

Chester Stock in 1936 described Harrington's extinct mountain goat, Oreamnos harringtoni, based upon six skeletal elements recovered from Smith Creek Cave, Nevada. Until recently it was rarely encountered in fossil deposits of western North America and was inadequately understood. One hundred ten skeletal elements recovered from eight dry cave and wood rat midden deposits in the Grand Canyon, Arizona, enable a re-examination and redescription of the extinct species. Characters of the skull indicate that O. harringtoni was distinct from, yet similar to O. americanus, the living form. The extinct species was generally smaller overall than O. americanus, with proportionally more robust jaws. Occasionally, the fossil forms are as large as the extant species. Preserved keratinous horn sheaths and large cuboid dung pellets assigned to O. harringtoni provide carbon isotope ages directly on the extinct species. The youngest age determined on horn sheaths is 12,580±520 B.P., while the youngest age from large cuboid dung pellets is 10,870±200 B.P., both from Stanton's Cave. Hair assigned to the extinct species indicates that it had a white coat. Plant fragments in the dung indicate it ate predominantly grasses, but it also browsed heavily on Ceonothus-Cercocarpus, Prunus, Pseudotsuga, and Sphaeralcea. Oreamnos harringtoni appears to have been restricted to the Great Basin-Intermountain Region, and evolved from an ancestral population of O. americanus since the Sangomonian, in less than 100,000 years. The species became extinct by approximately 11,000 B.P.