This study examined the foraminifera and the ecologic conditions of the benthic environment of the Oregon shelf and the uppermost slope (75-550 m depth) between 143°45' N and 144°40' N. Seasonal collections monitored the near-bottom marine environment and the sedimentary substrate at 16 stations. The foraminiferal benthic fauna was examined from eight seasonal stations and two additional stations. Use of a multiple corer provided randomly selected subsarnples of the sediment for ecologic and faunal analyses. Use of water bottles that triggered upon bottom impact provided measurements of the water as close to the bottom as 0. 6 m. Computerized data processing and statistical analyses aided the ecologic and faunal evaluations. The environmental study showed the existence of considerable variation in the hydrography of near-bottom waters, especially between summer and winter (upwelling and non-upwelling) collections at the same station. Upwelling conditions directly affect the benthic Redacted for Privacy environment. In addition, the water at any one place, at least dciring upwelling, was so well mixed that vertical stratification did not exist between 0.6 and 5.0 m off the bottom. Statistically significant sea-. sorial variations in surface sediments at the same station were not observed. The living benthic foraminiferal fauna exhibited considerable within-station variation both in species composition and in specimen size of selected species. The percent abundance of individual dominant species varied in adjacent cores (subsamples) by amounts up to 46%. Living specimens of a single species were found that were three times as large as the smallest living specimen from the same sample, yet there was no evidence of a multimodal size distribution resulting from age classes. The author suggests that the dominant species are aggregated and that the aggregations are colonies of asexually produced siblings. Lack of fit of species-frequency curves to the lognormal distribution indicated that relatively few species are fit to reproduce in a particular environment; most juvenile specimens that enter a particular environment belong to species that will not thrive there and either die or simply maintain growth with little chance of reproductive success. The existence of colonial aggregations of individuals is considered to provide the best explanation of the observed variations between adjacent samples. However, the observed variations could be due to sampling error or to substrate microheterogeneity. A possible natural community of 15 dominant species has been determined for those species that form a consistent part of each other's biologic environment. The community crossed the depth and substrate boundaries upon which the stations were selected and appeared to be a general community for the Oregon outer shelf. The limits of the community appear to be determined mostly by water depth, with approximate boundaries at 75-100 m and somewhere between 200-500 m. Regression analyses to determine the ecologic control on the foraminiferal fauna did not indicate a close correspondence between faunal parameters and environmental variables. Regression analyses to determine the ecologic control on mdividual species indicated that most species depended upon a set of two to four environmental variables rather than upon one single limiting factor. The set for each species was different. Temperature. phosphate concentration and oxygen concentrations were common hydrographic members of sets; percent silt, percent sand, percent clay, organic carbon content and organic nitrogen were common sedimentary members of sets. / Graduation date: 1972

The foraminiferal population of Yaquina Bay was investigated to attempt a correlation of seasonal changes in the hydrography with observed changes in the faunal distribution patterns. The results are based on data from two spatial surveys conducted in July 1966, and late February and March, 1967. The hydrography of Yaquina Bay undergoes seasonal changes closely paralleling the seasonal precipitation pattern. Except for short-term variations, the estuarine system is partly-mixed during the period of maximum river discharge (November to May) and wellmixed from June through October. Coastal upwelling (high salinity, low temperature) has a marked influence on the hydrography of the lower bay during the summer; maximum salinities and temperatures prevail in the upper reaches of the estuary during late summer and fall. Species associations were determined by the Fager-McConnaughey correlation coefficient method; similar assemblages were found for both summer and winter surveys. A marine biofacies fauna, dominated by Elphidium microgranulosum and E. frigidum, occupies the main estuary channel for about five miles upstream. The distributional patterns of the living fauna show evidence of a stronger marine influence during the summer, corresponding to a similar pattern in the hydrography. In the lower bay, the Elphidium fauna is displaced laterally by an assemblage characterized by Trochammina charlottensis and Elphidium incertum in the middle intertidal zone. This assemblages in turn gives way to an Ammobaculites exiguus -Miliammina fusca fauna in the upper intertidal area. The Elphidium assemblage gives way to a Miliammina fauna in the upstream direction. Trochammina inflata, T. macrescens, Miliammina fusca, Jadamminina polystoma, Haplophragmoides sp., H. hancocki and Siphotrochammina lobata are the principal species found in the marine marsh. Zones of environmental similarity were defined by the index of affinity association analysis. Living and total faunas of both winter and summer surveys were considered separately; several sample groups were defined in each case. Index of affinity data can also be used to provide an index of the marine influence on the foraminiferal population of the estuary. Species diversity or the average number of species/sample, ranges from 22 in the marine biofacies zone to six on the lower bay tideflats. An intermediate value (l0/sample)was found for the marine marsh. Highest standing crops were found in the marshes (summer) and on the tideflats adjacent to the lower bay channel, averaging 40 and 42/cm² respectively. Lowest values (1 to 2 cm²) were found in the middle to upper intertidal areas of the lower bay during the summer. The distribution of the total fauna is quite similar to that of the living population. Highest average values (175/cm³) are again found in the marine marsh and in the marine biofacies zone (70 to 80/cm³). Lowest values occur on the lower bay intertidal areas (3 to 9/cm³). In general, the percentage representation of agglutinated species in the total fauna increases with distance upstream in the channel and with distance laterally from the channel axis. Faunas of some marsh stations are composed entirely of agglutinated species. The percentage of calcareous hyaline species shows an inverse relation to that of the agglutinated fauna, increasing in importance with approach to marine conditions. Porcelaneous and planktonic species are generally minor constituents in the total fauna and are restricted to the marine biofacies as it is developed in the estuary. Foraminifer-ostracod ratios are extremely variable in the environments sampled in Yaquina Bay. Smooth-valved species are characteristic of the marine marsh and inner bay environments; valve ornamentation tends to increase with approach to marine conditions. Thecamoebians are present in low numbers throughout the estuary. In general however, the number of species and population size increases in the upstream direction. / Graduation date: 1968

60 leaves, 7 leaves of plates : ill. ; 28 cm Thesis (M.A.)--University of Oregon, 1943 Bibliography: leaves [51]-53

One hundred and seventy-four species and varieties of fossil Foraminifera are recorded from thirty-eight localities in the Siletz River Volcanics, Yamhill and Nestucca Formations exposed along Mill and Gooseneck Creeks, in the Northern Coast Range of Oregon. Marginulina holmesi is described as new. The Foraminifera indicate that this sequence was deposited during late Ulatisian and Narizian time, in marine waters at bathyal or lower neritic depths, with cool surface temperatures. The Yamhill Formation can be correlated with Moody Shale member of the Toledo Formation and the Coaledo Formation of Oregon; the McIntosh and Aldwell Formations of Washington; and the upper part of the Canoas siltstone member of the Kreyenhagen Formation and the Alhambra Formation of California. It is proposed to modify, in part, the type section of the Yamhill Formation. Approximately 2.2 miles of the section, south of the Yamhill River Fault, are excluded from the original type area. Biostratigraphic studies of foraminiferal faunae from adjacent sides of the Yamhill River Fault suggest only minor vertical displacement.

Examination of stream and roadcut exposures of the Cowlitz Formation allows the selection of measured representative sections, and collection of fossils, from an area roughly defined by the intersection of the boundaries of Clatsop, Columbia, Tillamook and Washington counties in Oregon. The study defines the features of the local environment of deposition, correlates sections to derive a composite columnar section, and develops a checklist of species for both microfossils and megafossils of the Cowlitz Formation.