Graduation date: 1953

Graduation date: 1961 / For master (tiff) digital images of maps contained in this document contact scholarsarchive@oregonstate.edu

Graduation date: 1983

Thirty three species of ammonites are recorded from the composite type section of the Weberg Member of the Snowshoe Formation in the Suplee area, Grant County, Oregon. Holcophylloceras burkei, Euhoploceras westi, E. tubereulosum and Strigoceras taylori are described as new, while four new species belonging to the genera Sonninia [?], Bradfordia, Pseudotoites and Witchellia are not formally named. Three ammonite zonules characterize the ammonite sequence of the type Weberg composite section. The sequence correlates with parts of the standard lower and middle Bajocian (Jurassic) of northwestern Europe. In addition, four associations (paleo-communities) of benthic mega invertebrates, the Gervillia, Protocardia, Isocyprina and Bositra buahii associations are delineated. The type Weberg composite section is a record of a local marine transgression westward onto an island system. The section also represents sedimentation over an irregular pre-Snowshoe topographic high, and indicates a progressive change from proximal to distal source of pre-Snowshoe sediments, from high to low energy conditions, and perhaps a slight deepening of the ocean bottom. Ammonites are rare in the lower division of the Weberg Member, locally present in fine sandy limestones of the lower part of the upper division, abundant and most diverse in silt-rich, clay-poor limestones of the upper part of the upper division, and locally abundant in mudstones of the Warm Springs Member. Recurrent associations of certain ammonite species, strong correlation of the associations with lithofacies and biofacies, and pervasive faunal differences of ammonites between facies indicate in general that the distributional patterns of the ammonites reflect spatial life-habitats. The spotty yet widespread geographic occurrence of several ammonite species suggest they had undergone extensive planktic dispersal, thus ocean currents probably played an important role in their distributional patterns.

No description available.

The northeast quarter of the Dutchman Butte quadrangle straddles the boundary of the Mesozoic Klamath Mountains province and the Tertiary Coast Range province. The boundary in this area is controlled by a major easttrending fault zone, herein named the Canyonville fault zone. Jurassic Rogue, Dothan, and Otter Point Formations have been offset right-laterally at least 40 kilometers. In latest Jurassic and early Cretaceous time, the fault zone formed the shoreline along which sediments of the Myrtle Group were deposited. Movement on the Canyonville fault zone becale down-to-the-north in Eocene time forming the southern margin of the Eocene Coast Range basin. Rocks of the lower to middle Eocene Roseburg and Lookingglass Formations thin and pinch-out, and become shallow marine to nonmarine in character southward across the fault zone. Fault movement decreased in Lookingglass time, and essentially ceased by Tyee (middle Eocene) time. Eocene structures in the thesis area formed contemporaneously with sedimentation; individual structures controlled and were controlled by the stratigraphy of the Eocene units.

The volcanic stratigraphy and petrography is described for a 46 km2 area on the southern flank of Mount Jefferson in the north-central part of the Oregon High Cascades. Here, volcanic processes have been active throughout Quaternary time, resulting in complex stratigraphic relationships. In addition, three formerly recognized glaciations and a two-phase period of neoglaciation have eroded the terrain, depositing tills in contact or interstratified with the volcanic units. Collectively, these processes and the resulting deposits are characteristic of High Cascades development.

The southeast part of the Portland Basin has been previously described by other investigators. However, little detailed information existed on the depositional relationships between the units, the various sedimentary fades, or the origin of many of the units.

Pleistocene marine terraces of the northern Oregon coast are an important factor in understanding the tectonics and paleoseismicity of the central Cascadia subduction zone. The lowest marine terrace, tentatively correlated to 80,000 year old Whiskey Run terrace of southern Oregon, is intermittently exposed in the present day sea cliff along an 80 km section of coastline between Tillamook Head and Cape Kiwanda. Terrace sediments consist largely of fine material such as clay, silt and fine sand with several locations containing large amounts of gravel derived from nearby headlands and steep bedrock hills. The terrace sediments are interpreted to be deposited in back-barrier marine environments, such as a bay, very similar to the bays which presently exist on the northern Oregon coast. Interbedded with terrace sediments are peat horizons which represent buried marsh or forest surfaces. These peat horizons have gradational lower contacts and abrupt upper contacts with terrace sediments indicating that the marsh or forest surfaces formed gradually above sea level and were suddenly downdropped below sea level to be buried by bay sediments. Such features are consistent with a seismically active Cascadia subduction zone which produces interseismic coastal uplift and coseismic coastal subsidence.

Graduation date: 1971