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...
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 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...
Fossil foraminifers from the Coaledo and Bastendorff Formations
near Coos Bay in southwestern Oregon were studied in an attempt
to determine the age and environment of deposition. Fresh unweathered
samples were collected from sea cliffs between Cape
Arago and Charleston, Oregon.
A large late Eocene delta is preserved in the...
During the Pleistocene, an andesitic volcano named Mount
Mazama grew to a probable elevation of 3000 meters in south-
central Oregon. Near the end of the Pleistocene, three diverse
magma types appeared in the eruptive products associated with Mount
Mazama: l)High-alumina basaltic andesite magma associated with an
early plateau and...