1. Education

Introduction

By

The Oregon Outback is a colorful name for the portion of the state lying in the Basin and Range physiographic province. (more below)
Old US395 north
Photo (c) Andrew Alden, licensed to About.com (fair use policy)
In early June 2005, taking the long way from San Francisco to Seattle, I drove from Alturas, California, to Bend, Oregon. The most memorable part was state route 31, the federally designated Outback Scenic Byway. Its whole length is in the Basin and Range, a geologic province we normally associate with Nevada. Oregon's portion of the Basin and Range was high and lonesome, but also green at this time of year. This photo of old US395 and many others in this gallery are available in large desktop versions for your free personal use.

The Basin and Range is the result of the North American plate being stretched as the smaller plates to its west were subducted and broken up during the Miocene Epoch (23 to 5 million years ago). The hot lower crust stretched in a plastic fashion while the brittle upper crust tore into rocky strips that foundered in the soft rock below, tilting into widely spaced ranges with basins between. This activity was accompanied by ferocious volcanism and the emplacement of widespread metal deposits. During wet times the basins became lakes; in dry times like today most basins dried into dusty playas. Most of these events are visible in the rocks and landforms along the Outback Scenic Byway.

  1. About.com
  2. Education
  3. Geology

©2014 About.com. All rights reserved.