Only ten million years ago, much of Oregon’s landscape was a relatively flat, oak-studded grassland. Then, the crust of southeastern Oregon began to stretch westward. That process continues today. Consequences include breaks — faults — in the crust, as well as volcanic eruptions. Faults caused mountain ranges such as Steens Mountain and Abert Rim, to rise above basins, like the Alvord Desert and Klamath Basin. To accommodate the crust stretching out, the Brothers Fault Zone developed along the northern boundary of the Basin and Range Province. Earthquakes occur along many of these faults. The faulting created cracks in the crust, and lavas — some very explosive — rose and erupted. This process continues today. Newberry Volcano, south of Bend, is among the most recent.
In this window, you can see the different landscapes developing in eastern Oregon as the continent is being pulled apart, while western Oregon exemplifies the opposite process: plates converging together (Window 2). The High Lava Plains Project is one of many research initiatives aimed at better understanding the processes driving the earthquakes and volcanic activity of southern Oregon. The window also highlights some of these earthquakes, including the 1993 Klamath Falls quake.
Digging Deeper: For more information, visit these websites.
Oregon’s Basin and Range (DOGAMI):
http://www.oregongeology.com/sub/learnmore/BasinRangeOwyheeuplands.HTM
Oregon’s High Lava Plains (DOGAMI):
http://www.oregongeology.com/sub/learnmore/HighlavaPlains.HTM
Digging Deeper: For more information, give this sample of books a read:
Living with Earthquakes in the Pacific Northwest, 2nd Edition by Robert S. Yeats (2004, OSU Press [http://oregonstate.edu/dept/press/])
Geology of Oregon, 5th Edition by Elizabeth L. Orr and William N. Orr (2000, Kendall/Hunt [http://www.kendallhunt.com/]) Professors at the University of Oregon, the Orr’s have been writing about Oregon’s geology for decades.
In Search of Ancient Oregon by Ellen Morris Bishop (2003, Timber Press [http://www.timberpress.com/]) Take a photographic journey through time and see Oregon’s ancient places.
