Saturday, November 3, 2018
Trip Leader: Steve Goldberg
This COGS field trip will explore several iconic examples of hydrovolcanoes in central Oregon. Hydrovolcanoes are produced by the interaction of magma or magmatic heat with an external source of water, such as a lake or an aquifer. After cinder cones, hydrovolcanoes are the second most common volcano type on continents and islands. The most common structure produced by a hydrovolcano is either a tuff ring or a tuff cone. We will visit three locations that exhibit these structures: Hole in the Ground, Fort Rock, and Table Rock. Each of these volcanoes erupted explosively within or near the ancient Fort Rock Lake. The rocks at each stop tell an amazing story, so we’ll learn how the volcanic processes are unraveled at the outcrops.
This will be a long day with considerable driving time. The driving time from Bend to the first stop at Hole in the Ground is approximately 1¼ hours, and the return to Bend from the final stop at Table Rock is under two hours. The roads in and out of Hole in the Ground are the roughest of the trip, and roads at Table Rock are also quite rough. A high-clearance vehicle is highly recommended. Bring a lunch, plenty of water, and ensure that your vehicle has a full tank of gas prior to leaving. The only gas station or store along our route after La Pine is in Silver Lake, following the last stop.
We will leave for the field trip at 8:00 AM from the southwest corner of the Walmart parking lot, 20120 Pinebrook Blvd., Bend. Please plan to meet 15 minutes prior to departure. The return to Bend should be no later than 6:00 PM.
Central Oregon Geoscience Society
P.O. Box 2154, Bend, Oregon 97709