Geology Commons^™

The Stratigraphy And Structure Of The Columbia River Basalt In The Clackamas River Drainage, James Lee Anderson

Dissertations and Theses

The Clackamas River drainage within the western Cascade Range is approximately aligned with a northwest trending lineation defined by the Portland Hills and the Brothers Fault zone. This area is occupied by an extensive Columbia River Basalt sequence that is deeply incised by the Clackamas River and its tributaries. Two major basalt units of the Yakima Basalt Subgroup, including the Grande Ronde Basalt and the Frenchman Springs Member of the Wanapurn Basalt, are distinguishable in a 515 meter to 550 meter accumulation. Of particular interest is the presence of five trending right-lateral strike-slip faults is consistent with a stress model …

A Study Of Estuarine Sedimentation In South Slough, Coos Bay, Oregon, Charles Allen Baker

Dissertations and Theses

Sediments in the South Slough Estuarine Sanctuary, Coos Bay, Oregon, were sampled and studied in order to determine the sources, dispersal systems and depositional facies of sedimentation. The purpose of the study was to establish baseline measurements and observations on the existing sediment conditions within the relatively undisturbed South Slough Estuarine Sanctuary

Petrology Of The Bull-Of-The-Woods Intrusive Complex, James Streshley Jackson

Dissertations and Theses

An area of unmapped intrusions lies within the Bull-of-the-Woods Roadless Area of Mount Hood National Forest. A variety of andesites, dacites,and diorites intruding units of tuff and andesite lava flows crop out over.an area of 52 sq km. These intrusions do not appear on the Geologic Map of Oregon West of the 121st Meridian (Hells and Peck, 1961). The purpose of this investigation is to map and describe these intrusions, with attention to the following questions:

What is the petrographic and geochemical nature of these intrusions?

What is the order of emplacement of these intrusions?

What is the probable mechanism …

Stratigraphy And Petrography Of The Selah Member Of The Ellensburg Formation In South-Central Washington And North-Central Oregon, Mavis Hensley Kent

Dissertations and Theses

The Ellensburg Formation of south-central Washington and north-central Oregon has been described by many workers from the time of the original description by Russell (1893) to recent work by Schmincke (1964). However, detailed information concerning the stratigraphy and petrography of the Ellensburg Formation in south-central Washington and north-central Oregon is not available. This study is among the first detailed studies made for a member of the Ellensburg Formation; it provides a specific comparison with the type Ellensburg of central Washington.

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.

Biostratigraphy Of The Snowshoe Formation (Jurassic) In The Izee Area, Grant County, Oregon, Paul Lawrence Smith

Dissertations and Theses

Using the standard Jurassic zonal scheme, this work attempts to determine the ages of the four members of the Snowshoe Formation that crop out in the Izee area. As a corollary, regional correlations are possible. The stratigraphic relationship between the Snowshoe Formation, the subjacent Hyde Formation and the superjacent Trowbridge Formation is also investigated.

Over one thousand fossils were collected from five stratigraphic sections and eight localities. The sections were measured using tape and compass techniques and the relative stratigraphic ranges of the fossils calculated using a computer program written specifically for this project. The ammonite fauna, dominated by the …

Stratigraphy, Structure, And Petrology Of The Snoqualmie Pass Area, Washington, Lawrence A. Chitwood

Dissertations and Theses

The Snoqualmie pass area lies about 50 mi (80 km) east of Seattle, Washington, along the crest of the Cascade Range. Five stratified units, forming a composite section over 22,000 ft (6700 m) thick, are recognized in the area. They were deformed and later intruded by granodiorite and quartz monzonite porphyry of the Snoqualmie batholith (middle Miocene). The oldest unit, the Denny Formation (Permian), 7000 ft (2100 m) thick, consists of interstratified basalt, andesite and dacite volcanic rocks and limestone and chert beds. This formation is unconformably overlain by a thick conformable sequence of early Tertiary strata which are subdivided, …

The Geology Of The Castle Rock Area, Grant, Harney And Malheur Counties, Oregon, John David Wood

Dissertations and Theses

The geology of the Castle Rock area aids in the understanding of Cenozoic volcanic stratigraphy and structures in an area where these volcanic rocks thin near the margins of the pre-Tertiary basement rocks and structural trends are overlapping. The Castle Rock area is unique in several aspects and is important in understanding and interpreting the geology in adjacent regions which have all been studied, at least on a regional basis. Intrusive ash-flow bodies of the Dinner Creek Ash-Flow Tuff, well-exposed sections of complexly interstratified volcanic rocks and well-exposed faults, and of high amount of erosional relief are features which make …

Structural Geology Of The Northeast Quarter Of The Dutchman Butte Quadrangle, Southwest Oregon, Rauno K. Perttu

Dissertations and Theses

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. …

Geology Of The Breitenbush Hot Springs Area, Cascade Range, Oregon, Clifford Michael Clayton

Dissertations and Theses

The Breitenbush Hot Springs area lies on the boundary of folded middle to late Tertiary Western Cascade rocks and younger High Cascade rocks. Within the mapped area the Western Cascade rocks are represented by four formations. The Detroit Beds, a sequence of interstratified tuffaceous sandstone, mudflow breccia, and tuff, is overlain unconformably by the Breitenbush Tuff. The Breitenbush Tuff consists of three units of welded pumice-rich crystal-vitric ash-flow tuffs interbedded with tuffaceous sedimentary rocks. The Outerson Formation unconformably overlies the Breitenbush Tuff and consists primarily of basaltic lava and breccia.

The Outerson Formation includes three localized members: a basal, glassy, …

A Mineralogical And Geochemical Study Of The Ferruginous Bauxite Deposits In Columbia County, Oregon, And Wahkiakum County, Washington, Ronald Laverne Jackson

Dissertations and Theses

Wet chemical analysis and instrumental neutron activation analysis (INAA) were performed on a suite of samples from three residual ferruginous bauxite profiles in the study area for abundances of Al₂O₃,

SiO₂, Fe₂O₃, Ti O₂, Na, Sc, Hf, Cr, Co, La, Sm, Yb, Lu, and Th. In addition a mineralogical study accompanied this research, using petrographic, differential thermal, and x-ray diffraction techniques. In each profile, the relative mobility of these elements were calculated by empirical methods for comparison with the parent rock and mineral properties in the saprolite.

This …

A Preliminary Investigation Of The Land Use Limitations Of The Major Landforms Along A Portion Of The Lincoln County Coast, Oregon, Richard Kent Mathiot

Dissertations and Theses

This study of a portion of Oregon's Lincoln County coast describes the physical limitations to land use of the various landforms in the study area. Seven major landform types comprise the study area: beaches, active dunes, stabilized dunes, marsh land and tidal flats, marine terraces, basaltic headlands, and uplands. Descriptions and evaluations of their physical characteristics, distribution, geologic and and engineering characteristics, and potentially hazardous processes are contained in the maps, figures, and text.

Environmental Geology Of The Marquam Hill Area, Roger Alan Redfern

Dissertations and Theses

This work on Marquam Hill area in Portland, a relatively undeveloped urban hillside area, is a pilot study in which environmental factors are evaluated quantitatively in order to delineate limitations on development. The study was undertaken at the request of and in cooperation with the City of Portland Planning Commission and with the State of Oregon Department of Geology and Mineral Industries. Factors considered include various aspects of the land, vegetation and attitudes of inhabitants. Findings are not intended to satisfy need for individual site studies by qualified experts but should show where that expertise is needed.

Field data were …

Biostratigraphy Of The Type Yamhill Formation, Polk County, Oregon, Larry R. Gaston

Dissertations and Theses

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 …

The Bedrock Geology Of The Southwest Part Of The Kachess Lake Quadrangle, Washington, David Carl Lofgren

Dissertations and Theses

The southwestern part of the Kachess Lake quadrangle lies between Lakes Cle Elum and Kachess, on the east flank of the central Cascade Range of Washington. The region lies between the North and South Cascade petrologic provinces, and includes rocks typical of each. Pre-Tertiary Easton Schist (called the Shuksan Suite farther north), and the Late Cretaceous-Paleocene Swauk Formation occur widely in the North Cascades, while the Tertiary Silver Pass Volcanics and Teanaway Basalt are typical of South Cascade volcanic sequences. Diabasic dikes of the Teanaway dike swarm occur throughout the vicinity.

The area is bounded on the west by a …

Granulometric Analysis Of Recent Sediments Of Tillamook Bay, Oregon, Gennaro William Avolio

Dissertations and Theses

The author has sampled the recent bottom sediments in Tillamook Bay, Oregon. Sediment distribution is assessed in relation to sediment source areas and related to sedimentary environments. Particular attention was directed to the precision with which granulometric data can be stated. It was found that variance is quite high for granulometric parameters of the bay sediments.

Sediment distribution using different measures are displayed on charts of the bay. Size distributions of sediments at any given location are examined for geologic significance. Plotting of size distribution on graph paper using probability ordinate is shown to increase the ease of geologic interpretation. …

A Tectonic Study Of A Part Of The Northern Eagle Cap Wilderness Area, Northeastern Oregon, Kenneth Gordon Neal

Dissertations and Theses

Upper Triassic metavolcanic and metasedimentary strata in the study area are intruded by the Hurricane Divide and Craig Mountain Plutons of the Late Jurassic-Cretaceous Wallowa Batholith. The Clover Creek Greenstone is overlain by the Martin Bridge Limestone, which is in tum overlain by the Hurwal Argillite; although the sequence is in normal stratigraphic order, contacts are generally tectonic. Concurrent with Early-Middle Jurassic regional deformation, during intermediate to mafic dikes, emplacement of the plutons of the Wallowa Batholith began. The plutons intruded vertically through the greenstone and limestone and then horizontally above the greenstone. This resulted in intense penetrative plastic deformation …

The Characteristics And Genesis Of Stone Stripes In North Central Oregon, John Baine Pyrch

Dissertations and Theses

Stone stripes are linear accumulations of rock debris separated by finer material and oriented down the steepest available slope. In north central Oregon, the stone stripes are composed of basalt fragments and occur where the soil mantle averages less than 1 m in depth. They are best developed in areas of higher elevation, usually from about 900 to 1100 m, and are most prominent on convex to straight slopes of 15 to 30 degrees. The stripes vary from a few meters to over 150 in length, and their widths range from 0.3 to over 3 m. The depth of the …

The Geology Of The Southeast Quarter Of The Bone Mountain Quadrangle, Oregon, Richard Cortland Kent

Dissertations and Theses

This thesis is a study of the geology of the southeast quarter of the Bone Mountain Quadrangle. The bedrock geology mapped includes about 56 square miles.The Klamath Mountain and Coast Range Provinces of southwestern Oregon are represented in the area. Rocks in the area include the Rogue, Dothan Riddle, Days Creek, upper member of the Umpqua and Tyee Formations. The ages of these rocks range from Late Jurassic to middle Eocene. Late Jurassic ultramafic and mafic intrusive rocks associated with the Rogue Formation occur in the Klamath Province. The metavolcanics of the Rogue Format ion and an associated linear belt …

Geophysical And Geological Analysis Of A Fault-Like Linearity In The Lower Clackamas River Area, Clackamas County, Oregon, Ronald Jay Schmela

Dissertations and Theses

A fault-like linearity along the lower Clackamas River is evaluated by analysis of physiographic and structural alignments, geological relationships, and by gravity and magnetic data. The study has resulted in the verification of a structural feature extending along the Clackamas River and the eastern front of the Portland Hills.

Physiographic alignments were examined in twelve 15 minute and two 7-1/2 minute quadrangle maps. A significant northeasterly morphologic trend, N. 20⁰ W. and N. 40° W., and other secondary trends, namely, the N-S, E-W, and N. 50-60° E., has developed in the Portland area. The consistent northwest trend is observed throughout …