Geology Commons^™

Biostratigraphy Of The Type Weberg Member, Snowshoe Formation, Grant County, Oregon, David G. Taylor

Dissertations and Theses

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 …

Analysis Of A Gravity Traverse South Of Portland, Oregon, Terry Dean Jones

Dissertations and Theses

The state gravity maps of Oregon and Washington show a gravity high centered south of Portland, Oregon and a gravity low in the Tualatin Valley to the west disrupting the regional gravity gradient which is controlled by crustal thickening. Detailed gravity surveys done in the Portland area are consistent with the state gravity maps but show considerably more detail. Quantitative interpretation of this data has provided new information on the subsurface structure in this area; recent work has yielded corroborative evidence for a fault zone bounding the east side of the Portland Hills, and has indicated the presence of faults …

The Petrology And Stratigraphy Of The Portland Hills Silt, Rodney Thomas Lentz

Dissertations and Theses

Topics in geology, which inevitably excite professional discussion and even tempered debate, often present challenging targets for the exploratory jabs of Master's degree candidates. The Portland Hills Silt and the controversy concerning its genesis provides just such an object.

Although the physical descriptions of the silt are generally in agreement, they remain somewhat generalized and, at present, no single definition is generally accepted. Moreover, incongruities concerning structural and textural details--notably, the presence of minor stratification and/or scattered pebbles in the silt--have resulted in considerable disagreement regarding its mode of origin.

Middle And Upper Eocene Biostratigraphy (Foraminifera) Of The Cascade Head Area, Lincoln And Tillamook Counties, Oregon, Arden D. Callender Jr.

Dissertations and Theses

An almost complete sequence of middle and upper marine strata, informally designated in this study as the "Strata of Cascade Head", has yielded 334 species and varieties of fossil Foraminifera. The Foraminifera were collected from 38 localities in four stratigraphic sections measured along the Salmon River, Neskowin Creek, Cascade Head Road, and near the town of Three Rocks in the central Oregon Coast Range.