Graduation date: 1968

Holocene hemipelagic deposition of terrigenous silts and clays dominates sedimentation on most of the Oregon and Washington continental slope. The sources of these sediments, the mechanisms causing sediment dispersal, and the relative contributions of the various continental sources to the marine deposits have been investigated using quantitative mineral and geochemical data for the 2-20 μm and the <2 μm size fractions. In the 2-20 μm size fraction, material derived from the Klamath Mountains and the California and Washington Coast Ranges contains chlorite and illite, but only Klamath material contains hornblende. Columbia River material lacks chlorite, and the Oregon Coast Range source is dominated by smectite. In the <2 μm fraction, source area compositions are less distinctive due to the ubiquity of smectite, but the northern and southern sources again contain both chlorite and illite. Regional and local mineralogic and textural variations in the fluvial sediments reflect geologic and geographic changes between drainage basins. Amorphous material is a minor component in the 2-20 μm fraction of the fluvial sediments, but may form 25-50% of the <2 μm fraction in some source areas. Sediments derived from all source areas are transported north and northwestward across the margin, either by a poleward-flowing undercurrent along the slope, by wind-driven surface currents on the shelf and associated turbid layers on the slope, or by a combination of the two processes. Columbia River <2 μm material may also be carried southward along the shelf and upper slope by summer surface currents. The poleward undercurrent (an eastern boundary undercurrent) appears to have limited sedimentological significance when compared to the role of the western boundary undercurrent in sediment transport and deposition on the continental slope and rise of the eastern United States. Linear programming has been applied successfully to estimate source area contributions to the 2-20 μm marine sediments. The influence of each source is largest in proximal environments, and the contribution estimates indicate that material derived from each source area is transported northward along the margin. Similar estimates for the <2 μm material are considered unreliable because of internal inconsistencies and the uniform nature of the <2 μm compositions used in the modelling. The contributions have been used to calculate a sediment budget for the 2-20 μm fraction. This budget indicates that the mass accumulating on the entire slope within the study area contains 47% Columbia River, 32% Klamath Mountain, and 21% California Coast Range material in the 2-20 μm fraction, and demonstrates the importance of multiple sediment sources and sediment mixing in the formation of hemipelagic sediments on the continental margin. / Graduation date: 1982

Changes in sea level during the past 20,000 years are recorded in sediments taken from the continental shelf off the Rogue River, Oregon. Sea level has risen approximately 125 m. during the Holocene (Curray, 1965) and the general transgression has been interrupted by several stillstands and minor regressions. Box core samples taken in the area of investigation depict the nature of sedimentation during the last rise of sea level as well as present-day equilibrium sediment relationships. Three sediment facies, a recent fine-grained mud, a basal transgressive sand, and an intermediate sediment, believed to be a mixture of the other two, are defined on the shelf on the basis of textural parameters. The mud facies dominates surface sediment on the central shelf while the sand facies is the most commonly exposed on both the inner and outer shelf. The percentage of sand generally increases with depth in the box cores, often producing a change in sediment facies with depth and demonstrating the transgressive nature of the sediments. Grain-size analysis of the sand fraction of the offshore sediments reveals that offshore sands are finer-grained and better sorted than those occurring on the present beaches. The offshore sands most likely represent relict nearshore deposits and not ancient beach sands which would occur lower in the sediment sequence. High concentrations of heavy minerals are found in the sand fraction of the offshore sediments as well as in beach sands in the area. Brief stillstands of sea level may be reflected in depths where the offshore sands contain anomalously high percentages of heavy minerals. Opaque minerals, chiefly magnetite, occur in placer accumulations on the present beaches and high percentages of these minerals in the offshore sands may be indicative of submerged beach environments associated with stillstands of sea level. The magnetite may be concentrated in sufficient quantity in the placers to produce detectable magnetic anomalies, several of which have been recorded in the area. Other lines of evidence used to determine the depths of probable stillstands of sea level are bathymetric relief, the distribution of shallow water fauna in sediments from deep water, and the distribution of rounded gravels on the shelf. A compilation of the several lines of evidence suggests several stillstands of sea level associated with the Holocene transgression occurring at depths of 18, 29, 47, 71, 84, 102, and 150 meters. / Graduation date: 1969

The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. / Graduation date: 1970

A deep source-receiver seismic refraction experiment was conducted on the upper part of the Monterey Deep Sea Fan. The aim of this thesis is to construct the velocity structure of the upper Monterey Fan and to examine the lateral seismic velocity variations among the upper, middle and lower fan subunits. Using primary waves and whispering gallery phases (the multiply-reflected refraction waves), the sediment velocity structure was modeled by the tau-zeta travel time inversion process. The changes in velocity gradients with depth of the upper Monterey Fan are morphologically similar to that found on both the Central Bengal Fan and the Nicobar Fan, an abandoned lower fan of the Bengal Fan Complex. The velocity gradient of the upper Monterey Fan at depth, 0.59 s⁻¹ is significantly lower than both the middle Bengal Fan (0.68 s⁻¹) and the Nicobar Fan (0.81 s⁻¹). The upper fan subunit, which is closer to its sediment source, is characterized by higher porosities caused primarily by a higher sedimentation rate than the lower fan subunits. Since seismic velocity is inversely related to porosity, the upper fan subunit should have lower velocity gradients and seismic velocities than the other fan subunits. If porosity and velocity variations exist, then these variations can be used to constrain various models of deep sea fan formation. No definite conclusion can be drawn at this time due to a fault within 1 km of the Nicobar Fan site; however, a systematic velocity variation pattern of deep sea fans is revealed. Some portions of the Monterey Fan data contain refracted waves which have bottomed within the underlying acoustic basement structure. The entire velocity structure was solved by both the general and the "stripping" solving schemes. The results of basement structure show a velocity ranging from 3.4 to 5.8 km/s indicating that the uppermost part may be pre-existing continental rise sediments. / Graduation date: 1986

Until recently, few collections of the marine brown alga Phaeostrophion irregulare S. et G. had been made, little was known of its ecology, and virtually nothing of its life history. The main objectives of this investigation were to study the life history and major factors influencing growth and distribution of this species. Laboratory and field investigations were conducted during 1961-196i4. Life history studies were performed in the laboratory by culturing zoospores under constant environmental conditions. The growth of cultured germlings and the photosynthetic response of the laminate plants from the field were recorded under different temperatures, salinities, nutrients, and light conditions. The tolerance of laminate plants and germlings to extremes of temperature, salinity, and desiccation was also determined in the laboratory. The growth and reproduction of in situ plants at Glacier Point, British Columbia were correlated with temperature, salinity nutrients, tides, sand and various meteorological conditions at that locality. Life history studies were conducted at Glacier Point by observing the succession of germlings on denuded transects and by transplanting laboratory cultured germlings into the field. The laminate thallus of P. irregulare sometimes bears both unilocular and plurilocular sporangia at the same time. Previously, only unilocular sporangia were reported in this plant. Zoospores from the unilocular sporangia (unispores) and plurilocular sporangia (plurispores) develop identicallys, and each is capable of producing a laminate thallus directly or after a succession of filamentous and discoid plethysmothalli. The "direct-type" of development of the zoospores (unispores) from the unilocular sporangium is probably due to a suppression of meiosis in the unilocular sporangium. Morphological and cultural evidence is presented to support this hypothesis, although no cytological evidence was obtained. At Glacier Point, P. irregulare is restricted to sandy areas, and the greatest number of plants occur where large fluctuations of sand occur annually. The plants are regularly buried four to six months per year, and their growth and reproduction is limited to the period when sand is absent. Competition with other plants probably accounts for the occurrence of P. irregulare in sandy areas, since it will grow in rocky areas if other algae are eliminated. The period of maximum growth (February to April) is associated with a corresponding increase in light intensity and water temperature in this area. After April, growth in non-tide pool populations decreases much more rapidly than growth of tide pool populations, because of the increased exposure of plants to desiccation during daylight. A period of decreased growth for tide pool plants occurs in May to June; this decrease probably results from high surface water temperatures, high light intensities, or a combination of both. The morphology of the laminate plants of P. irregulare is extremely variable and the range of variability observed at Glacier Point overlaps that described for P. australe from Callifornia. P. australe is considered to be a growth form of P. irregular, and is therefore a taxonomic synonym of P. irregulare, Distributional evidence also supports this conclusion. The known range of P. irregulare extends from Point Conception, California to Khantaak Island, near Yakutat, Alaska. Temperature is considered to be the primary factor controlling its gross distribution. Nitrate and phosphate deficiency may partially restrict the distribution of P. irregulare south of Point Conceptions, California. The sporadic distribution of P. irregulare on the Pacific Coast is correlated with the presence of sand, and local conditions are most important in determining its regional distribution. Experimental studies show that P. irregulare is well adapted to a sandy habitat, and several features are discussed to explain this adaptation. The laminate plants and germlings of P. irregulare tolerate a wider range in temperature and salinity in culture than that to which they are subjected in nature. However, the laminate plants and germlings of P. irregulare are very sensitive to desiccation; under experimental conditions both tolerate less desiccation than that to which they are subjected under natural conditions. / Science, Faculty of / Botany, Department of / Graduate

Understanding how large-scale processes (>100 kms) influence ecological communities is currently a major focus in ecology. In marine systems, coastal upwelling, a large-scale oceanographic process in which surface water pushed offshore by winds is replaced by cold, nutrient-rich water from depth, appears to cause variation in rocky intertidal communities. Along the central Oregon coast upwelling occurs intermittently during the summer while on the southern coast it begins earlier in the spring and is less variable throughout the summer. Coastal upwelling can affect rocky intertidal communities by altering the delivery of nutrients, larvae, and phytoplankton. I conducted three studies on both the southern and central Oregon coast to understand how differences in upwelling affect rocky intertidal community structure and dynamics. In the first study, I examined the recruitment and growth rates of sessile invertebrates (mussels and barnacles). Recruitment of both mussels and barnacles, and growth of mussels were consistently higher on the central Oregon coast than the southern coast. Upwelled water is nutrient-rich, so differences in upwelling are likely to affect growth rates of macroalgae. In the second study, I tested this hypothesis by monitoring the growth of two species of intertidal kelp at both central and southern coast sites. During El Ni��o years, when upwelling is sharply reduced on the central Oregon coast, algae may fare better at sites on the southern coast where upwelling is less affected. However, during years when upwelling is strong all along the coast, nutrient limitation does not appear to differentially affect macroalgal growth rates. Finally, in the third study, I examined the influence of upwelling on the interactions between microalgal primary producers and herbivorous limpets. I conclude that this interaction is complex and varies both within and between upwelling regions. My research suggests that a transition in upwelling from weak and sporadic on the central Oregon coast to stronger and more persistent on the southern Oregon coast drives the striking differences in rocky intertidal community structure and dynamics between these areas. / Graduation date: 2003

Graduation date: 1991

Bowie Seamount, a submerged volcano situated off the west coast of Canada at 53° 18; N, 135° 39' W, has a relief of 10,000 ft. and comes to within 100 ft. of the ocean surface. It is made up of a series of intersecting ridges which together give the mountain an overall northeast - southwest elongation. It appears to be a combination central and fissure type volcano which has been built up over a system of intersecting fractures in the oceanic crust. Two terraces form the flattened summit of the volcano at approximate depths of 45 and 130 fathoms. These are thought to be the remains of platforms produced by combined wave erosion and shallow-water vulcanism during late Quaternary time when sea level was lower than it is today. The last phase of volcanic activity on the summit occurred after the formation of the upper terrace no more than 18,000 years ago. Samples dredged from the upper half of the volcano include: pillow fragments, fragments of non-pillowed flows, pillow breccias, bombs, tuffs, ash, and unsorted tephra. The rocks are mainly alkali olivine basalts, accompanied by rare andesites which, presumably, were derived by differentiation of the basaltic magma. Feldspathic and gabbroic inclusions, many of which appear to be cumulates, are common in the basalt. Ice-rafted rocks are rare on the summit of Bowie Seampunt but are common on its nearest neighbour - Hodgkins Seamount. A ferro-manganese deposit, apparently over 1 million years old, that exists on the summit of Hodgkins Seamount, suggests that this peak is relatively much older than the summit area of Bowie Seamount. Palagonite appears to form as the initial phase of weathering of glassy basalts in the area of study but the products of more advanced weathering are montraorillonite and zeolites. Rock fragments that have been rounded by chemical weathering are common. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Viable cysts collected from natural sediments were induced to excyst. Ten cyst-theca relationships, first established elsewhere, were confirmed for British Columbia (B.C.). These were: Gonyaulax tamarensis, Protoperidinium aspidotum, P. claudicans, P. conicoides, P. conicum, P. cf. denticulatum, P. leonis, P. oblongum, and P. punctulatum. Five cyst-theca relationships were established for the first time: Peridiniopsis cf. hainanensis, Protoperidinium sp. nov., P. thorianum, and two apparently new species of Gonyaulax. P. pentagonum was found to have a cyst different from the cyst of this species in the Atlantic. Forty-five samples from Recent sediments were collected along the coast of B.C. Twenty-three of the samples had very few cysts. Hidden Basin was the chief source of viable cysts for the excystment experiments. Ten cyst-based taxa were described from the sediment samples. These were: Operculodinium centrocarpum, the cyst of Scrippsiella faeroense (= Micrhystridium bifurcatum), Spiniferites belerius, S. bentori, S. bulloideus, S. elongatus, S. membranaceus, S. nodosum, and S. ramosus. Tanyosphaeridium sp. has been recorded previously as the cyst of Polykrikos schwarzi. Two new cyst-based taxa are described for the first time. These are a cyst of Protoperidinium sp., and Spiniferites "sp. A". Cyst assemblages in the Recent sediments of B.C. were similar to many temperate estuarine and neritic areas. Some cysts which are characteristic of these areas in other regions, have not yet been found in B.C. The relative importance of some cysts also varies from that found in similar sediments elsewhere. The dominance of Operculodinium centrocarpum in many of the cyst assemblages, including B.C., is a pattern typical of temperate estuarine conditions. Some cysts appear to be characteristically associated with fjord environments. Scrippsiella faeroense, for example, has been found in Norwegian fjords and Scottish sea lochs as well as some B.C. fjords and inlets. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate