University of Washington Publications in Geology The Geomorphology and Volcanic Sequence of Steens Mountain in Southeastern Oregon

Cover

Introduction

Location
Name
Field Work
Culture
Accessibility
General Geology and Scope of Investigation

Previous Literature

General Reconnaissance Work
Local Stratigraphy in Adjacent Regions
Origin of the Structure
     Normal Faulting
     Genetic Importance of Step Faults
     Volcanic Vents Associated with the Scarps
     Circular Fault Basin
     Absence of Folding and Other Compressional Effects
     Even Distribution of the Deformation
     Effects of Compressional Deformation in the Columbia River Plateau
     Absence of Marked Lateral Movement

Geomorphology of Steens Mountain

Northern Steens
High Steens
Southern Steens and Its Relation to Pueblo Mountain
The Eastern Scarp of Steens Mountain
     Structure
     Erosion
          Drainage
          Glaciation
          Differential Erosion
          Wind Erosion
          Landslides

The Volcanic Sequence

Summary
Alvord Creek Beds
     General Characteristics
     North of Alvord Creek
South Fork of Alvord Creek
North of Little Alvord Creek
     Fossil Content
Early Intrusions in the Alvord Creek Beds
     Basaltic Sill
     Rhyolitic Laccolith
     Elongate Acidic Vent
Pike Creek Volcanic Series
     Lower Tuffs
     Lower Laminated Rhyolite
     Middle Tuffs and Their Stratigraphic Equivalent to the South
     Upper Laminated Rhyolite
     Little Alvord Creek Rhyolite
     Upper Tuffs
     Biotite-Dacite
Rhyolitic Rocks of Cottonwood Creek and Willow Creek
Steens Mountain Andesitic Series
     Basic Andesite
     The Great Flow
          General Features
          Petrology of the Great Flow
     Upper Andesitic Series
          General Features
          Distribution
          Petrology of the Upper Andesitic Series
Steens Mountain Basalt
     General Description
     Distribution
     Age Relationship
     Petrography
     Basaltic Intrusions
The Later Series