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Eastern Columbia River Gorge Field Trip

New Light on the Neogene Geology of the Eastern Columbia River Gorge Area

Registration is now closed.

A two day field trip under the guidance of an all-star cast of geologists that not only know the story but can enthusiastically tell the geologic story of this dynamic area. Field stops, several that have not been ‘field-tripped’ before, and discussion will focus on the tectonic, volcanic and stratigraphic history of The Dalles Basin, the Klickitat Canyon, and the Simcoe Back Arc Volcanic Field. Major geologic events and deposits preserved in the cited areas will be visited over the course of the two days. At the conclusion of the field trip, participants will enjoy a special appreciation of the geologic features and processes that have created this diverse geologic area. Minimal walking/hiking will allow any and all interested individuals an opportunity to enjoy this trip.


Dr. James Anderson, Professor of Geology at the University of Hawaii, Hilo, Co-leaders: Terry Tolan, Senior Hydrogeologist, Intera Inc. - Geoscience and Engineering Solutions, and Dr. Steven (Steve) Reidel, Professor of Geology, Washington State University – Tri-Cities.

Words from the Leader

“The landscape of the eastern Columbia River Gorge and adjacent areas has been shaped by the combined effects of deformation of bedrock, erosive action by the Columbia River and its tributaries, and powerful episodic ice-age outburst floods.   This trip will provide an opportunity to experience all of these things. 

Our stops will include visits to spectacular exposures of Yakima Fold Belt structures within the Columbia Hills anticline and the Horse Heaven Hills anticline at Grayback Mountain.  These exposures occur along the shores and in the canyon walls of the Columbia River Gorge near The Dalles, Oregon and along the Klickitat River canyon in Washington.  An important theme will be the complex interplay between Yakima Fold structures and northwest-trending strike-slip faults.

The Klickitat River locality, at Grayback Mountain, includes an ancient Columbia River canyon that was formed during the emplacement of the Columbia River Basalt, more than 12 million years ago.  In this same area, and above the CRB canyon, there is an early canyon of the Klickitat River that formed more than 4.8 million years ago.  The CRB canyon contains both the Pomona and Elephant Mountain members separated by an interbed of Columbia River sediment (Rattlesnake Ridge Member of the Ellensburg Formation). 

During this trip, we will also see basalt lava flows of the Simcoe Mountains volcanic field within the Mosier Syncline and Klickitat Valley to the north.  These flows filled a 2.95 Ma canyon of the ancestral Klickitat River along more than 20 miles of its length. This part of the canyon is offset, along its course, by strike-slip faults. Remnants of this canyon are visible in walls of the present Klickitat River canyon.”


June 11th and 12th, 2016
Meet in The Dalles at 8:00 am (place to be announced)
Depart to the field by 8:30 am

Field Trip Participation Policies

If you wish to participate in this field trip, please contact Dave Olcott at (503) 695-519 or The sign up at the banquet will reserve you a spot until April 15th; thereafter, payment accompanied by a registration form must be received by May 16th. All participants must be GSOC members or a guest of a member. Minor participants under 18 years of age are required to have permission in writing from a parent or legal guardian; minors must be accompanied by a responsible adult GSOC member designated by their parent or legal guardian. The letter of permission must be attached to the registration form.

Number of Participants

At this time the number of participants is limited to 24. So that we can monitor an accurate count of participants, please check with Dave before submitting a registration form. An alternate list will fill any vacancies that may occur due to unforeseen circumstances.


Transportation will be by two, fifteen passenger vans. Having a professional in each van will permit discussion and answers to questions in transit, not just at field trip stops. Participants will need to arrange their own transportation to The Dalles and to the designated point of departure each morning.


Each participant must arrange for his/her overnight lodging. There is a diverse offering of motels and hotels in The Dalles as well as campgrounds not far to the east and west. Those individuals that wish to commute from Portland each morning must be aware that we will be leaving the rendezvous site at 8:30 am.           

Trip Cost/Assessment

An assessment fee of $75.00/person will cover the cost of van rental, gasoline, insurance, printing, and honoraria for leaders.

Things to do if you are planning on participating

  1. Print your name on the sign up sheet (banquet) or call Dave Olcott (503) 695-5219, to reserve a spot.
  2. Complete registration and payment online or turn in the registration form at a GSOC       meeting/speaker or mail to GSOC, PO Box 907, Portland, OR 97207-0907 by May 16th.
  3. Arrange your lodging and check with fellow participants for sharing transportation to The Dalles. A participant list will be emailed as soon as the group has been finalized.
  4. Bring sack lunches and snacks for Saturday and Sunday.
  5. Bring water bottle, hat, sunscreen, sunglasses, hand lens, and binoculars.
  6. Wear/bring appropriate clothing – may be warm, cold, wet, dry, muddy, and windy

Additional Details will be emailed, to all participants, as the field trip date nears.