The Vale KGRA is characterized by high heat flow, two to five times higher than the worldwide average, and by numerous hot springs. The hot springs are aligned along faults. This phenomena is typical of a Basin and Range type geothermal system. The hot geothermal fluids migrate upward along the more permeable, fault planes. The rocks exposed in the Vale area are the Pliocene Chalk Butte formation and the Pleistocene beds of Captain Keeney Pass. Both units are composed of volcaniclastic siltstones, sandstones and conglomerates. The units are differentiated by color, texture and degree of lithification. About 200 meters of the Chalk Butte formation and 100 meters of the beds of Captain Keeney Pass are exposed in the area. Silicification is wide spread in the rocks of the Chalk Butte formation.

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.

A major change in sedimentary and structural style occurs in Eocene strata exposed along the southern margin of the Oregon Coast Range. Lithofacies of the early Tertiary Umpqua Group have been described, mapped and assigned to likely depositional environments. Submarine fan and slope facies (upper Roseburg Formation) overlie Paleocene basaltic basement rocks to the north, whereas fluvial, deltaic and shallow marine facies (Lookingglass Formation) overlie Franciscan-equivalent strata to the south along the flank of the Klamath Mountains. These two depositional systems are gradational into one another, and were prograding northwestward until about 52 Ma. Means of clast compositions from sandstones and conglomerates from both the Roseburg and Lookingglass Formations suggest derivation from identical recycled orogen or arc-continent collision sources in the Klamath Mountains. Change from Klamath-parallel to more north-south structural trends is well displayed within early Eocene strata of the Umpqua Group. Five major fault systems involve lower Umpqua (Roseburg and Lookingglass) strata, and were active while deposition was taking place. All these faults ceased to be active at about 52-50 Ma, and are overlapped by the middle Eocene Tyee Formation. Regional strain analysis indicates more than 20 percent shortening by right-lateral convergence during early Eocene time. The structural style and syn-tectonic deformation of marine slope facies suggest deposition in an active subduction complex until about 52 Ma. Structural trends in the southern Oregon Coast Range parallel those in the adjacent Klamath Mountains until the end of the early Eocene. At 52-50 Ma, subduction apparently ceased as incoming seamounts clogged the trench, and may have jumped to an outboard position near the present day coastline. In middle Eocene time, the newly developed forearc region rapidly filled with sediments from a much sandier depositional system. Paleomagnetic studies of relatively undeformed Tyee forearc strata indicate as much clockwise rotation as the much more deformed, underlying volcanic basement of the Oregon Coast Range. Rotation of the Oregon Coast Range as a single crustal block must have occurred after, rather than during seamount accretion to the continental margin, which was essentially complete by 52 Ma.

Graduation date: 1964

Graduation date: 1952

Graduation date: 1996

The thesis area consists of 33 square miles in the south-central Pueblo Mountains of Humboldt County, Nevada and Harney County, Oregon. The Pueblo Mountains are tilted fault block mountains found in the extreme northwestern part of the Basin and Range province and were produced during Early Tertiary Basin and Range orogeny. Northwest and northeast trending faults of Late Tertiary time have since cut the entire stratigraphic sequence. The oldest rocks exposed are metamorphosed Permian to Triassic eugeosynclinal sedimentary rocks. The metamorphic sequence is intruded by several granitic plutons of Late Jurassic to Middle Cretaceous age. A thick sequence of Miocene basalt flows unconformably overlies the pre- Tertiary rocks. A slight angular unconformity separates the basalt sequence from overlying Miocene tuffaceous sedimentary rocks, sillar flows, and welded tuffs. Unconsolidated deposits of Quaternary alluvium include alluvial fan and lacustrine sediments. Mineralization within the area includes several gold prospects, a mercury prospect, and a possible copper deposit. The copper prospect consists of a large gossan (6, 000 feet by 3, 000 feet). Mineralization and alteration from a Cretaceous porphyritic quartz monzonite intrusion has produced potassic and quartz sericite hydrothermal alteration in the host. Oxidation and weathering has removed the sulfides from the surface leaving goethite, hematite, and limonite residues. / Graduation date: 1971

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Published paleomagnetic studies have shown that the Oregon Coast Range has rotated 60° clockwise since middle Eocene time, probably by pivoting either during collision of a seamount terrane or during an episode of asymmetric extension within western North America. Eocene sedimentary deposits within the Oregon Coast Range basin, in particular the Tyee Formation, document changes in basin evolution that provide geologic constraints for proposed rotation models. The Tyee Formation comprises an arkosic petrofacies which is different from underlying lithic sandstones that were derived from the adjacent Klamath Mountains. Isotopic study of sandstones of the arkosic petrofacies, including Sm-Nd, Rb-Sr, K-Ar, and ¹⁸O analyses, indicate that much of the sandstone was not derived from the Klamath Mountains or nearby Sierra Nevada. The source area most likely included S-type granites of the Idaho Batholith. Lithofacies within the Tyee Formation include a sandy deltaic system to the south, a thin muddy shelf/slope sequence farther north, and a thick basinal sequence of sandy high-density turbidites that grade northward into low-density turbidites. Absence of facies segregation within the turbidite sequence precludes application of classical deep-sea fan depositional models and forms the basis for the delta-fed submarine ramp model introduced here. Delta-fed submarine ramps are short-lived sandy systems that result from rapid rates of progradation as well as aggradation. Synchronous changes in depositional style, structural deformation, sandstone composition, and rates of tectonic subsidence of the Oregon Coast Range basin are interpreted to record the transition from collisional trench-fill deposition to a subsiding forearc basin. The Tyee Formation was deposited after collision was complete and yet is rotated as much as the seamounts on which it lies; therefore, rotation must have occurred subsequent to collision. Since these sediments were partially derived from the Idaho Batholith region, the Oregon Coast Range probably lay much farther east during deposition and subsequently rotated westward to its present position. Tectonic rotation of the Oregon Coast Range may have resulted from continental extension that began in the Pacific Northwest about 50 Ma. Paleogeographic reconstructions show that basin development was synchronous with regional extension, arc migration, and tectonic rotation throughout the Pacific Northwest.

The Fountain Landslide located along I-84, five kilometers east of Cascade Locks, Oregon has moved periodically for over thirty years. Aerial photographs taken prior to recorded movement of the landslide show the headscarp of a large preexisting landslide. In 1952 a cut was made into the toe of the landslide to straighten Highway 30. The recorded movement history begins at this time. Stabilization procedures in the late 1950's focused on dewatering the slide mass. Movement had nearly stopped by 1957. A deeper cut was made into the toe of the landslide in 1966 to widen the highway to the four-laned I-8ON (later renamed I-84). Accelerated movement resulted. The Oregon State Highway Division removed 264,000 cubic meters of material from the head of the movement zone. Accelerated movement continued. The Oregon State Highway Division then began intense research of the landslide. Research included core logs, slope inclinometers, and the ground water data. The western portion of the slide mass was unloaded more extensively in 1970 (1.2 million cubic meters). This later unloading slowed down the movement, but it continues periodically. The oldest unit found in the area is a volcaniclastic unit. It is found only in core logs in the SW portion of the slide. The basalts of the Columbia River Basalt Group are found intact and as talus in the study area. Quartz diorite intrusives younger than the Columbia River Basalt Group is found at the surf ace and at depth along the entire length of the toe of the landslide. Wind River Lava crossed from Washington, dammed the Columbia River and was deposited within the study area. The slide mass consists primarily of Columbia River Basalt Group talus and Wind River Lava talus. The slip plane consists primarily of rocky mudstone. The ground water table is elevated over the intrusive at the toe of the landslide and over the volcaniclastic unit at the head. Surface cracks and scarps indicate that the slide mass moves northward, drops at the head and heaves at the toe. A slope stability analysis of the Fountain Landslide showed that the instability here is the result of elevated groundwater and the removal of material at the toe for highway construction. It also showed that the eastern portion is more stable than the western portion. The differences in the stability result of the addition of fill at the toe and a lower ground water table in the eastern portion. The development of the prehistoric slide resulted when the dam of Wind River Lava was removed and lateral support for the deposit was lost. This study shows that it is essential to have adequate geologic information prior to construction or remedial design for any preexisting landslide to avoid stability problems.