"It is the purpose of this paper, through a brief review of the history of Astoria, to construct a framework of the physical history of the city, to place each published geologist in his correct historical setting within the city, and to reestablish his locales so as to be presently...
Clay minerals from sediment samples obtained on Astoria Fan were analyzed by X-ray diffraction. Clay minerals are defined for the purpose of this study as crystalline phyllosilicates less than two microns in equivalent settling diameter. The clay minerals are subdivided into the five common families: montmorillonite, chlorite, vermiculite, illite, and...
This is the second report of a study designed to establish the
current patterns and water mass characteristics existing along the
Oregon coast. Surveys reported on previously were concerned with
monthly samples from a maximum depth of 100 feet and out to 25 miles
offshore from Newport, Oregon. Since December...
There are seven stratigraphic units exposed in the Picture
Gorge quadrangle, a 204-square mile area in east-central Oregon.
isolated exposures of pre-Cretaceous serpentinites, metalimestones,
and other metamorphic rocks record marine deposition
of sands silts, and limy sediments followed by burial, lithification,
peridotite intrusion, and several periods of deformation. Intrusion
and...
The Molalla quadrangle is located in northwestern Oregon along the eastern edge of Willamette Valley about 30 miles south of Portland. The area includes part of the Western Cascade foothills as well as a portion of the Willamette Valley lowland. The rocks in the Cascade foothills are marine and terrestrial...
The Corvallis fault is a 50 km long northeast-trending structure, part of which defines the boundary between the central Willamette Valley and the east-central Coast Range of Oregon. Previously the fault had been mapped as either a high-angle reverse or normal fault, with the east block down. New gravity data...
Surface geology, seismic data, petroleum exploratory well data, and water well data
have been used to analyze the structural and tectonic history of the southern Willamette
Valley. Tertiary strata beneath the southern Willamette Valley appear to have had an early
Cascade or Clarno volcanic source to the east by the...
Nearly 9,000 feet of Cretaceous mudstones, shales, sandstone,
and conglomerates are exposed along the northeast-trending Mitchell
anticline of central Oregon, These rocks are divided into two formations
on the basis of criteria developed in this investigation. The
lower formation, hereby designated the Meyers Formation, is 4,716
feet thick at its...
The thesis area covers 165 square miles including the greater
part of the northeastern quarter of the Mitchell quadrangle in north-central Oregon. The three stratigraphic units exposed in the area
consist of a variety of Tertiary volcanic rocks including the Clarno
Formation, the John Day Formation, and the Columbia River...
The southern half of the upper Nehalem River basin contains
the most complete section of lower to middle Tertiary marine sedimentary
and volcanic rocks in northern Oregon. Determination of
stratigraphic relationships of six formations, and their depositional
environments and provenance is the chief objective of this paper.
More than 75...
The type section of the Mascall Formation, which is located in
the John Day Valley, is interpreted to represent a sequence of
paleosols. These fossil soils were formed on a floodplain during the
middle Miocene. The measured thickness of this section is 1340 feet,
and although the top of the...
The thesis area is located in the southeastern corner of Harney County, Oregon. This portion of Oregon is situated in the northern part of the Basin and Range province, and is characterized by both mafic and silicic extrusives, and localized nonmarine sediments and
tuffs ranging in age from middle (?)...
The Whitewater River area is located directly east of Mt. Jefferson in the Cascades of central Oregon. Approximately 90 mi2 (230 km2) were mapped (scale 1/24,000) and four new K-Ar ages and 151 major element analyses were obtained in a study of the stratigraphic
and magmatic transition from the Miocene...
The Mitchell inlier in north-central Oregon contains the largest exposure of Cretaceous marine sedimentary rocks in this region. Nearly 9,000 ft of Albian-Cenamanian rocks are exposed along the flanks of the Mitchell anticline. The Cretaceous section rests unconformably overlain by Tertiary volcanic rocks. The Cretaceous rocks have previously been divided...
The area studied in detail, known as the Antone District,
is located in the southeast corner of Wheeler County, Oregon, ,
between longitude 119 37. and 119°54 east, and latitude 44°23
and 44°3O' north.
Surface elevations range from 3050 feet above sea level in
the northeast corner of the district,...
Within 40 square miles of the southeastern Wallowa Mountains, Oregon, eugeosynclinal Permian and Triassic formations comprising a section about 25,000 feet thick have been exposed by uplift and erosion of overlying Miocene Columbia River basalt. Deposition appears to have been continuous from Permian into Upper Triassic, but an apparent angular...
Six early to middle Tertiary geologic units crop out in the
Saddle and Humbug Mountain area. They include the late Eocene to
early Miocene Oswald West muds tones, the lower Silver Point and
the upper Silver Point tongues of the middle Miocene Astoria Formation,
and the middle Miocene Depoe Bay...
Pre-Tertiary metamorphic rocks, Jurassic granitic intrusions,
and Eocene basalts are exposed along the North Fork of the John Day
River at its confluence with Granite Creek. Geochemical and textural
evidence suggest greenschist-metamorphosed, strongly sheared,
volcanogenic rocks originated in an island-arc environment. These
greenstones were apparently intruded during the Late Permian...
The Greenhorn Mountains contain a tectonic ally disrupted
ophiolite and both arc-derived and pelagic sediments. Age of major
sedimentary units within and bordering the thesis area is Early
Permian, based upon dates of conodonts and fusulinids from contemporaneous
but allocthanous limestones. Sediments near the south
boundary of the thesis area...
Supplement to Miscellaneous Paper 7 was published in 1966. For master (tiff) digital images of maps contained in this document contact scholarsarchive@oregonstate.edu
Pluvial Lake Chewaucan was a late Pleistocene lake, as much as 375 feet deep, covering 480 square miles in the northwestern part of the Great Basin in southern Oregon. The lake basin, now occupied by Summer Lake, Upper and Lower Chewaucan Marshes, and Lake
Abert, was formed by down-dropped fault...
The northwest one-quarter of the Prineville Quadrangle is
underlain by Tertiary and Quaternary volcanic and volcaniclastic
rocks of the Columbia River Basalt Group, and the Clarno, John Day,
Rattlesnake and Deschutes Formations.
The Clarno Formation is dominated by pyroxene-bearing
andesites, but also contains olivine-bearing basalts, oxyhornblende-bearing
dacite and rhyodacite flows...
The Bear Creek area is situated at the boundry between the Basin and Range Province, Deschutes Basin and Blue Mountains Province. It contains rock units representing most of the Cenozoic geologic column. The major rock units exposed are the Clarno Formation, John Day Formation, Columbia River Basalt Group, Deschutes Formation...
The northwest-trending Neogene Tualatin basin in northwestern Oregon is a pull-apart
basin with approximately 750 m of post-middle Miocene structural relief. Gently
tilted uplands capped by Columbia River Basalt Group surround the synclinal basin on all
sides. Integrated gravity, aeromagnetic, and seismic reflection data indicated that the
basin is underlain...
Eight Tertiary geologic units crop out in the Seaside-Young's River Falls area, including late Oligocene to early Miocene Oswald West mudstones; Angora Peak sandstone and Silver Point members of the middle Miocene Astoria Formation, and middle Miocene Depoe Bay and Cape Foulweather Basalts. Three new lithologically distinct
units, the 'J'...
Six Tertiary units are exposed in the Onion Peak area near the town of Cannon Beach., Oregon. The units consist of: late Eocene to
early Miocene Oswald West mudstones (informal), middle Miocene Astoria Formation (Angora Peak sandstone and Silver Point mudstone members.-informal), middle Miocene basalts of intrusive and extrusive Depoe...
The thesis area is located in the Blue Mountains of northeast Oregon. Pre-Tertiary and Cenozoic rocks, divided on the basis of age and tectonic history, are exposed along the eroded crest of the Blue Mountain anticline. Permian (?) metasedimentary rocks probably correlate with the Elkhorn Ridge Argillite, and consist mainly...
A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in...
Six Tertiary rock units are exposed in the Bear Creek-Wickiup Mountain-Big Creek area. They are: the late Oligocene to early Miocene Oswald West mudstones; the Big Creek sandstone member, the Pipeline member (a new unit), and the Silver Point mudstone member of the early to middle Miocene Astoria Formation; and...
Four distinct lithologic units compose the Tertiary rocks of the Neahkahnie Mountain - Angora Peak area, located along the northwest
Oregon coast near the town of Nehalem. The Tertiary units are the late Oligocene to early Miocene Oswald West mudstones, the middle Miocene Angora Peak sandstone member of the Astoria...
Five early to middle Tertiary bedrock geologic units crop out in the study area. These include the late Eocene to early Miocene Oswald West mudstones; the Tucker Creek sandstone, Big Creek sandstone, Silver Point mudstone, and Pipeline members of the
early to middle Miocene Astoria Formation; and the middle Miocene...
Five distinct lithologic units compose the Tertiary rocks in the Tillamook Head - Necanicum Junction area of the northern Oregon Coast Range. They are: the late Eocene to early Miocene Oswald West mudstones, the middle Miocene Angora Peak sandstone and
Silver Point mudstone members of the Astoria Formation, and the...
Twelve rock units, from upper Eocene to middle Miocene are exposed in the Nicolai Mountain-Gnat Creek area. They are, from oldest to youngest: Pittsburg Bluff Formation; Oswald West mudstone; Big Creek sandstone, upper Silver Point mudstone, and
Pipeline mudstone members of the Astoria Formation; Depoe Bay Basalt; Grande Ronde Basalt;...
The late Oligocene Yaquina Formation is exposed in an arcuate outcrop pattern which extends along the central Oregon Coast from
Siletz Bay on the north to Seal Rock on the south. Maximum inland extent of the Yaquina outcrop is :five miles. Maximum thickness of the Yaquina Formation is 2, 000...
In the area surrounding Clarno, Oregon, pre-Cretaceous metamorphics, Cretaceous marine sediments, and a varied assemblage of Tertiary volcanic rocks are known. The oldest exposures are of an homogeneously fine-grained, mildly metamorphosed, limy shale to which the term "Muddy Ranch phyllite" is applied. Non-metamorphosed, Cretaceous marine shales and graywackes, approximately 1500...
A thick sequence of intercalated andesite and basalt flows, tuffs, and volcanic sediments crop out in the Fly Creek Quadrangle and the north half of the Round Butte Dam Quadrangle. This sequence was deposited in the ancestral Deschutes River Valley along the east flank of the Cascade Range during the...
The thesis area is located in north-central Oregon approximately 20 km west of the town of Mitchell. The rocks exposed in the area belong to the Clarno Formation. This study supports the informal reclassification of the Clarno to Group status, composed of an Upper and Lower Clarno Formation. An angular...
The middle Eocene Tillamook Volcanics form the oldest rock unit in the Elsie-lower Nehalem River area. K-Ar age determinations and age constraints imposed by foraminiferal and calcareous nannofossil assemblages of overlying sedimentary strata indicate an absolute age of about 42 Ma for the uppermost Tillamook Volcanics. Major oxide values indicate...
The upper Eocene to lower Oligocene Oswald West mudstone is
the oldest formation (informal) in the Green Mountain-Young's
River area. This 1,663 meter thick hemipelagic sequence was deposited
in a low-energy lower to upper slope environment in the Coast
Range forearc basin. The formation ranges from the late Narizian
to...
Three realms of deposition, Marine, Fluviatile, and Marine-
Fluviatile, are recognized in Yaquina Bay, Oregon, on the basis of
sediment texture and mineralogy. The Marine Realm extends 1.5
miles into the entrance of the estuary and is typified by normal
marine salinity and vigorous tidal action. Sediments of this realm...
The middle to upper Eocene Tillamook Volcanics form the volcanic core or basement rocks in the Rock Creek-Green Mountain area. They consist of a thick sequence of high TiO2 tholeiitic basalt, basaltic andesite, and andesite subaerial flows and breccias. Detailed mapping, petrography, major oxide plots, magnetic polarity, and radiometric age...