Two land breeze events occurred off the Oregon coast on the nights of April 19th and 20th, 1973. An array of four moored toroid buoys and one land station recorded the effect of the land breeze event on the surface mesoscale wind and temperature fields. The land breezes may have resulted from the premature summerly conditions of fair weather and southward coastal winds that were caused by an early northeastward extension of the North Pacific High. The main features of the events were as follows: 1) A cooling period of a few hours after sunset established an air temperature gradient of -0.1° C km⁻¹ in the nearshore 10 km region. 2) The advance of the land breeze-front produced a 5° C temperature drop at the land station and a 1° C temperature drop at the buoy stations. 3) Simultaneously, the front also caused a decrease in wind speed by about an order of magnitude at each of the stations. During the passage of the front the wind veered from southward at 10 m sec⁻¹ to westward at 2 to 3 m sec⁻¹. 4) At dawn the temperature gradient was rapidly reversed, but there was a 2 hour lag before the wind speed began to increase. No frontal return flow was observed, instead the wind backed to the south and increased gradually over the array. Horizontal divergence and vertical vorticity were calculated using a simplified program. The land breeze produced spans of positive vorticity (5 x 10⁻⁴ sec⁻¹) over the array, possibly due to the horizontal wind shear in the offshore direction. The land breeze also caused a zone of convergence over the nearshore 10 km. The convergence was preceeded by a brief period of intense divergence. There was no convergence zone beyond the nearshore region. Instead there appeared alternating bands of convergence and divergence with a period of around 37 minutes. The same periodicity was observed in the offshore wind velocity. These features can be explained by a model of horizontal roll vortices migrating seaward from the nearshore convergence zone. The roll wavelength is inferred to be 4.7 km, the westward migration speed is 2 m sec⁻¹, and the height of the PBL is estimated to be 1. 5 km. This leads to a PBL Reynolds number of 370 ± 80, which is lower than previous observations and suggests that the rolls are produced by buoyancy and parallel instability. A model which is compatible with all the above is presented. / Graduation date: 1975

Graduation date: 1968

The movement characteristics of five landslides are compared and interpreted based on records of approximately 10-years duration. Condon landslide in the Oregon Coast Range has consistently exhibited brief (1 - 8 days) movement episodes in wet winter months, separated by long periods of no movement. The translatory movement is probably controlled by the orientation and structure of the underlying sedimentary rocks. From 1981 to 1990, annual movement averaged 109 mm, and individual events varied from 1 to 187 mm. All major movement events (> 10 mm in 4-10 days) were precipitation-induced. A non-linear relationship exists between movement rates and Antecedent Precipitation Index, which has a daily recession coefficient of 0.87. The API threshold for movement initiation was estimated to be 160 mm, based on 16 documented major events between 1984 and 1990. Groundwater level at the landslide responded to precipitation very quickly, with lag time usually less than 3 days. Movement started on days when the groundwater level rose above 2.5 m below ground surface, and a non-linear relationship exists between daily movement rate and groundwater level. Based on available data, there appears to be no change in movement characteristics of Condon landslide after two-third of it was clearcut in 1987. Wilhelm landslide, located near Condon landslide, has a similar movement pattern, but smaller movement magnitude (averaged 34 mm per year, 1985-1990). The Mid-Santiam and Jude Creek landslides in the volcanic terrane of the western Cascade Range move at much faster rates, averaging 3.8 and 7.8 m per year from 1982 to 1990, respectively. Unlike the Condon and Wilhelm landslides, where individual movement events correspond with individual storms, these two western Cascades landslides exhibit prolonged movement. The Mid-Santiam landslide moves all year, and annual movement shows little variation over the year. The other studied landslides all have large intra- and interannual variation in movement rates, and movement generally stops in the summer dry period. The Lookout Creek landslide (average annual movement = 79 mm, 1981-1990) has slowed in the past four years, and has exhibited movement patterns similar to the storm-dominated Coast Range slides. Geology and climatic patterns are the two most important factors contributing to the observed differences in timing and style of movement in the landslides studied. Climatic patterns trigger movement events, and geology influences movement patterns through control on geotechnical properties of landslide materials. These factors can be used to classify landslide movement patterns on a regional scale. / Graduation date: 1992

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Graduation date: 1985

Graduation date: 1967

Thesis (Ph. D.)--University of California, 1910. / "Note on sources": p. xi-xiii.

Thesis (PH. D.)--University of California, 1910. / "Note on sources": p. xi-xiii.

Thesis (M.A.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 67-70). Also available via the World Wide Web.

Heavy mineral compositions of sands from Oregon beaches, rivers and sea cliffs have been determined in order to examine the causes of marked along-coast variations in the beach-sand mineralogy. The study area extends southward from the Columbia River to the Coquille River in southern Oregon. The heavy-mineral compositions were determined by standard microscopic identification with additional verification by X-ray diffraction analyses. Initially the beach-sand samples were collected as single grab samples from the mid-beachface, but significant selective sorting of the important heavy minerals prevented reasonable interpretations of the results. Factor analysis of multiple samples from the same beach yielded distinct factors which correspond with known mineral sorting patterns. The effects of local sorting were reduced by the subsequent use of large composite samples, permitting interpretations of along-coast variations in sand compositions. Four principal beach-sand sources are identified by factor analysis: the Columbia River on the north, a Coastal Range volcanic source, sands from the Umpqua River on the south-Oregon coast, and a metamorphic source from the Klamath Mountains of southern Oregon and northern California. The end members identified by factor analysis of the beach sands correspond closely to river-source compositions, the proportions in a specific beach-sand sample depending on its north to south location with respect to those sources. During lowered sea levels of the Late Pleistocene, the Columbia River supplied sand which was dispersed both to the north and south, its content decreasing southward as it mixed with sands from other sources. The distributions of minerals originating in the Klamath Mountains indicate that the net littoral drift was to the north during lowered sea levels. With a rise in sea level the longshore movement of sand was interrupted by headlands such that the Columbia River presently supplies beach sand southward only to the first headland, Tillamook Head. At that headland there is a marked change in mineralogy and in grain rounding with angular, recently-supplied sands to the north and rounded sands to the south. The results of this study indicate that the present-day central Oregon coast Consists of a series of beaches separated by headlands, the beach-sand compositions in part being relict, reflecting the along-coast mixing at lower sea levels and subsequent isolation by onshore migration of the beaches under the Holocene sea-level transgression. This pattern of relict compositions has been modified during the past several thousand years by some addition of sand to the beaches by sea-cliff erosion and contributions from the rivers draining the nearby Coastal Range. / Graduation date: 1987