During Pliocene time a cluster of basaltic and basaltic andesite shield volcanoes was built in the
Three Sisters region. Included in this cluster are the North Sister, Little Brother, Husband, Wife,
Sphinx and Broken Top, the radial dikes and conduit fillings of which have been laid bare by
glacial erosion....
The northern part of the Southeast Three Sisters quadrangle straddles
the crest of the central High Cascades of Oregon. The area is
covered by Pleistocene and Holocene volcanic and volcaniclastic rocks
that were extruded from a number of composite cones, shield volcanoes,
and cinder cones. The principal eruptive centers include...
This is a study of the ecology of the timberline and alpine vegetation of the Three Sisters which are located in the
central Oregon Cascades. The Sisters are a close group of three 1O,000-foot volcanic peaks. Volcanic activity within the last few hundred years as well as recent glaciation have...
Ninety-five oriented samples were obtained from nine Recent
Cascade lava flows in Oregon. Directions and intensities of remanent
magnetization were measured on a spinner magnetometer which measures
directions of magnetization to within 1.2° s.d. Angle measurements
were plotted graphically using an equal area projection. Mean
directions and statistics were calculated...
The Western Lake Survey (WLS) of 1985 documented the status of lake water chemistry across the western US and inferred population representations of various subregions and geomorphic units via statistically analyses. Results from this 1985 study indicated that lakes of the Oregon Cascades had the second most pristine and dilute...
The Central Oregon High Cascade Range is an anomalously mafic segment of the Cascade Arc due to ongoing intra-arc extension, which allows most magmas to traverse the crust without stalling and evolving to more evolved compositions. North Sister, a composite volcano in this arc segment, has produced a seemingly monotonous...
