Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
The central Bond Creek area is on the north slope of the Wrangell Mountains approximately 15 miles east of Nabesna, Alaska. The entire area is underlain by plutonic rocks of the Monte Cristo batholith of probable Jurassic age. Early members of this complex are hornblende diorite, quartz diorite, and granodiorite...
The thesis area consists of 44 square miles in southeast Harney
County, Oregon. The Pueblo Mountains are located in the northwest
part of the Basin and Range structural province, and are characterized
by normal faults of large displacement that produced the tilted fault
block mountain range.
The oldest rocks exposed...
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...
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 Duke Point-Kulleet Bay area is located on the southeast
coast of Vancouver Island, B.C., approximately 60 miles northwest
of Victoria, B.C. and 25 miles west, across the Strait of Georgia,
from Vancouver, B.C. Approximately 2500 feet of Late Cretaceous
sedimentary rocks of the Nanaimo Group are exposed within the...
The Duzel Rock area includes four square miles in the eastern
Paleozoic subprovince of the Klamath Mountains southeast of Fort
Jones, California. The structurally complex terraine is composed
of Silurian graywacke, post-Silurian phyllite, limestone and basalt
associations, and minor andesitic intrusive rocks.
Three groups of sedimentary and extrusive rocks have...
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 Facey Rock area includes approximately 4 square miles in
the Eastern Paleozoic Subprovince of the Klamath Mountains north
of Callahan, California. The structurally complex terrain is composed
of sparcely fossiliferous Silurian graywacke, sparsely fossiliferous
Ordovician limestone, Devonian to Cretaceous chloritic
quartzite and minor gabbroic and dioritic intrusive rocks.
The...
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 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...
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...
The middle to late Eocene tholeiitic Tillamook Volcanics compose the oldest rock unit in the Hamlet-North Fork of the Nehalem River area. Geochemical plots and field relationships indicate that these rocks were produced in an extensional tectonic setting in the developing forearc and formed an extensive tholeiltic oceanic island. The...