An in-depth field study of the Delacroix Island producing field illustrates the evolution of the east-trending Delacroix Island Fault during the last 13 My. Well log correlations and 3-D seismic interpretation of 22 subsurface bio-stratigraphic horizons across the fault reveal variable stratigraphic thicknesses and displacement. Wells, with well log curve data as shallow as 31 m (100 ft) below the surface, were used to calculate interval thicknesses, expansion indices, sediment accumulation rates, burial history and magnitudes of displacement. Through these analyses, a correlation was found between the positioning of ancient Miocene depocenters over Delacroix Island and a period of increased fault activity. Historic satellite imagery (last 34 yrs) of the field depicts a lineation on the modern marsh surface coincident with the upward projected fault plane. Continuous wetland loss on the downthrown side of the fault trace suggests that recent and continued fault movement may be contributing to marsh submergence.

The West Crater-Soda Peaks area covering about 100 km is located 35 km southeast of Mount St. Helens in southern Washington State. It is one of several Quaternary monogenetic High Cascade volcanic centers overlying the Ohaaapecosh Formation of the Western Cascade Group and interstratified glacial till.These volcanic centers are the most westerly of the range.

The original purpose of this study was a detailed structural analysis of the Jurassic Otter Point Formation in order to determine if the Canyonville Fault Zone, which forms the northern boundary of the Klamath Mountains in the Riddle - Canyonville area (Benson and Perttu, 1980), extends westward to the coast and, if possible, to characterize the structure of the Otter Point Formation. Further, a detailed examination of the structural and stratigraphic relationships between the Otter Point Formation and the Eocene Roseburg and Lookingglass Formations was to be performed in an attempt to determine the tectonic history of the area.

The proximity of Miocene Columbia River basalts to the "locally-erupted" coastal Miocene basalts in northwestern Oregon, and the compelling similarities between the two groups, suggest that the coastal basalts, rather than being locally erupted, may be the westward extension of plateau basalts derived from eastern Oregon and Washington. The local-origin hypothesis is based largely on the interpretation of coastal dikes and sills as representing vent areas; however, a complex mechanism, as yet unsatisfactorily defined, would be required to cause the eruption of virtually identical magmas simultaneously from source areas 500 km apart. This study, therefore, has investigated the coastal basalt intrusions both laterally and vertically. Geochemical and paleomagnetic analysis was used to determine the occurrence and distribution of basalt units; gravity surveys enabled an examination of the subsurface extensions of basalt intrusions in sedimentary rocks.

The Chehalem Mountains area, encompassing 70 square kilometers, is at the western extent of the Columbia River Basalt Group as mapped in western Oregon. The flows in the study area were identified as belonging to subdivisions of the Columbia River Basalt Group on the basis of physical characteristics and trace element geochemistry. The basalt flows are poorly exposed in the area and weathering is deep and extensive where the flows have been exposed. Where erosion has exposed the underlying marine sedimentary rocks, the basalt has failed in landslides.

The Hood River Valley, located 100 kilometers east of Portland, Oregon, is in the transition zone between two geologic provinces--the High Cascades and the Columbia Plateau. The entire valley is probably underlain by Columbia River Basalt, but it crops out only on steep hillsides and in stream valleys. The base of the basalt is not exposed in the thesis area. The basalt is overlain by Pliocene and Quaternary basalt and andesite, volcanic sediments and glacial debris. The stratigraphy of the Columbia River Basalt is useful in determining the path of the basalt flows into western Oregon, in mapping the structure and in reconstructing the tectonic development of the northern Oregon Cascades.

Lithological, geophysical, paleontological and geochemical methods were used in order to define the contact relationship between the Keasey and the Cowlitz formations in northwestern Oregon. Drill cuttings from six wells located in Columbia County were analyzed by the Instrumental Neutron Activation Analysis (INAA) method. The concentrations of K, Th, Rb and Sc/Co ratio in the samples established four different groups: 1) High K, Rb, and TH, with low Sc/Co ratio typical of Cowlitz sediments. 2) Low K, Th and Rb and high Sc/Co ratio, more characteristics of the Keasey Formation. 3) Very low concentrations of Rb and high Sc, which is indicative of basaltic volcanism. 4) vertically varying K, Th and Rb concentrations. The provenance of group four is uncertain, but it may represent reworked sediments or the interfingering of the Keasey and the Cowlitz formations. Plots of these elements vs. depth define the geochemical contacts between the formations.

The Lower to Middle Ordovician Garden City Formation and Pogonip Group are coeval successions of mixed carbonate and siliciclastic rocks deposited under normal marine conditions on a shallow carbonate ramp on the western margin of Laurentia. The Garden City Formation was deposited in the Northern Utah Basin and the Pogonip Group was deposited in the Ibex Basin. These two basins experienced different rates of thermal subsidence following Neoproterozoic rifting along the western margin of Laurentia resulting in significant thickness differences between rock units and varying lithologic expressions of eustatic change. This study provides a unique opportunity to examine the lithologic, geochemical, and paleontological responses to eustatic oscillations of two coeval sedimentary basins in Utah that formed under different tectonic settings and subsidence rates. The Garden City Formation is composed of fourteen lithotypes and the Pogonip Group is composed of eleven lithotypes. These lithotypes mainly represent depositional environments ranging from inner ramp and middle ramp with minor outer ramp deposits. Many lithologies appear to be storm influenced due to the presence of abundant rip-up clasts (intraclasts), fragmented bioclasts, and occasional mega-ripples. Other lithologies have been extensively bioturbated and burrowed. Nine stratigraphic sequences have previously been identified within the Pogonip Group. Eight equivalent, albeit compressed, sequences within the Garden City Formation were located using biostratigraphic and chemostratigraphic correlations, and increases in insoluble residues often found at the bases of sequence boundaries. Sequences are expressed as deepening-upward packages containing silty/sandy lowstand deposits that transition into wackestones and lime mudstone-rich highstand deposits. Several sequence boundaries appear to coincide with conodont and/or trilobite extinction events. Important sequence boundaries mark the Sauk III-m and Sauk IV-m transition and the Ibexian- Whiterockian Series boundary. Meter-scale cycles are common and likely related to Milankovitch cyclicity. Insoluble residue increases upsection at each location which may indicate a gradual overall drop in sea level due to the onset of the regressive upper portion of the Sauk III supersequence. Insoluble residue from the Pogonip Group ranges from 1.2 to 84.7 wt. % with an average of 16.0 wt. % ± 0.7 wt. %. Insoluble residue from the Garden City Formation ranges from 1.5 to 63.8 wt. % with an average of 13.4 wt. % ± 1.0 wt. %. New stable carbon isotope data (δ13C) from the Garden City Formation and the Pogonip Group range from -2.92 to 1.23 ‰ V-PDB and -2.19 to 0.56 ‰ V-PDB, respectively. Four distinct δ13C trends are recognized in both sections: 1) a drop in δ13C from positive values between 0.2-1.0 ‰ to negative values approaching -1.0 ‰ near the base of the Ordovician, 2) a 0.5 to 1.0 ‰ positive δ13C excursion near the top of the Rossodus manitouensis Zone, 3) a drop in δ13C values to near -2.0 ‰ through most of the Acodus deltatus –Oneotodus costatus Zone, and 4) a gradual increase in δ13C from - 2.0 ‰ to -1.0 ‰ throughout the remainder of the sections. δ13C of the Garden City Formation and the Pogonip Group appear to be correlative based on these distinct trends. This correlative relationship was verified by the lowest occurrence of conodont species Scolopodus filosus and Scalpellodus n. sp. A of the Low Diversity Interval which coincides with the positive δ13C excursion in both the Garden City Formation and the Pogonip Group. New δ13C data likely represent global primary seawater chemistry based on the correlation of similar δ13C trends from the Argentine Precordillera and western Newfoundland.

Several previous Neoproterozoic microfossil diversity studies yield evidence for arelatively sudden biotic change prior to the first well‐constrained Sturtian glaciations. In an event interpreted as a mass extinction of eukaryotic phytoplankton followed by bacterial dominance, diverse assemblages of complex acritarchs are replaced by more uniform assemblages consisting of simple leiosphaerid acritarchs and bacteria. Recent data from the Chuar Group of the Grand Canyon (770‐742 Ma) suggest this biotic change was caused by eutrophication rather than the direct effects of Sturtian glaciation; evidence includes total organic carbon increases indicative of increasing primary productivity followed by iron speciation values that suggest sustained water column anoxia. A new data set (this study) suggests that this same eutrophication event may be recorded in shale units of the formation of Hades Pass and the Red Pine Shale of Utah’s Neoproterozoic Uinta Mountain Group (770‐742 Ma). Results of this study include a significant shift from a higher‐diversity (H’= 0.60) fauna that includes some ornamented acritarchs to a lower‐diversity (H’ = 0.11) fauna dominated by smooth leiosphaerids and microfossils of a bacterial origin (Bavlinella/ Sphaerocongregus sp.). This biotic change co‐occurs with a significant increase in total iii organic carbon values that directly follows a positive carbon‐isotopic excursion, suggesting increased primary productivity that may have been the result of elevated sediment influx and nutrient availability. Both the biotic change and period of increased total organic carbon values correspond with the onset of an interval of anoxia (indicated by total iron to aluminum ratios above 0.60) and a spike in sulfur concentration. Like those reported from the Chuar Group, these biotic and geochemical changes in the upper Uinta Mountain Group are independent of changes in lithofacies , and they suggest that either a eutrophication event or direct inhibition of eukaryotes by sulfide (or perhaps both) may have been the cause of the biotic turnover. These findings support current correlations between the Uinta Mountain and Chuar Groups, the idea that the biotic turnover preserved in both strata was at least a regional phenomenon, and current models of punctuated global ocean anoxia during mid‐ to late‐Neoproterozoic time. Whether or not this hypothesized eutrophication event was more than regional in extent remains a very interesting question and will certainly be a focus of future research.

The landscape evolution of the northeastern Uinta Mountains and the manner in which climatic and tectonic forcing have influenced it are not well constrained. Surficial deposits covering ~325 km2 below the glacial termini in the Henrys Fork and ~50 km2 along the Green River in western Browns Park were mapped at 1:24,000 scale to develop a Quaternary stratigraphic framework for the northeastern Uinta Mountains. The Henrys Fork mapping area spans from late Wisconsinan moraines to Flaming Gorge Reservoir. The Henrys Fork stratigraphy contains 10 mainstem gravels, six piedmont gravels, and landslide deposits. Terraces preserved along the Henrys Fork converge downstream and are strath terraces underlain by clast-supported, cobble gravel derived from the Uinta Mountain Group and Paleozoic limestone units. The Henrys Fork terrace stratigraphy was correlated to the Wind River terrace stratigraphy for age control, and incision rates were estimated at 80-110 m/m.y. The Browns Park mapping area includes Little Hole and continues through lower Red Canyon into westernmost Browns Park, ending at the Warren Draw-Swallow Canyon quadrangle boundary. The Browns Park stratigraphy includes eight mainstem gravels, five piedmont gravels, and various landslide, colluvial, and eolian deposits. A tuffaceous bed with Lava Creek Bash (640 ka) was identified near the top of a deposit at Little Hole that was previously mapped as Miocene basin fill. Minimum Green River incision rates were estimated between 90 and 115 m/m.y. using the Lava Creek Bash for age control. These rates are comparable to estimates for the Henrys Fork, but are about half of the rates reported for the south flank of the Uintas and other central Rocky Mountain ranges. A series of three distinct deposits in western Browns Park are interpreted as evidence for the landslide impoundment and subsequent outburst flooding of the Green River. These include slackwater deposits at Little Hole, an outburst flood deposit in western Browns Park, and a large paleolandslide deposit that lies between them. Estimates of sediment accumulation rates behind the paleolandslide dam suggest it was stable for ~605 years. Peak discharge estimates from impounded water volume estimates and paleoflow competence indicators suggest that the resulting outburst flood was ~22,000 m3/s.