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 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...
The volcanic rocks of the Harney Basin comprise a bimodal
assemblage of rhyolites (SiO₂ greater than 72%) and basalts (SiO₂
less than 52%). Tholeiitic basalts account for 15 rocks analyzed and
alkalic basalts for three. Most basalts contain phenocrysts of olivine
and plagioclase. Pyroxene phenocrysts were not found. Rhyolite
flows...
The thesis area consists of 33 square miles in the south-central
Pueblo Mountains of Humboldt County, Nevada and Harney County,
Oregon. The Pueblo Mountains are tilted fault block mountains found
in the extreme northwestern part of the Basin and Range province and
were produced during Early Tertiary Basin and Range...
The thesis area consists of approximately thirty square miles in the Southern Cascades of Washington near Mount Adams. The oldest exposed rocks are sedimentary volcanic clastics and pyroclastic flows of late-Oligocene age that form a homocline in the northwest corner of the area. A thick pile of younger Tertiary lavas,...