Volcanic Field Trip

July 8, 1995

This trip — for the Science & Education unit chaired by Joanne Vinton — visited several interesting geologic locations. Intrusive and extrusive igneous rocks are exposed in road cuts and in the steeper mountainous areas up the McKenzie Valley. Minerals and inclusions were viewed it the Nimrod granite. At Wolf Rock some bushwhacking allowed us to get to the base of this mysterious, exposed volcanic neck. The main discussion here was whether it resembled a wolf, a bison sitting down or an elephant. Proxy Falls provided the picturesque view for lunch. A short hike over recent lava flows takes you to two separate falls. The self-gided hike at the McKenzie Pass shows lava flow features. You can also see segments of the old road across the lava that early travelers used. Sawyer’s Ice Caves are a few hundred yards off the highway. We didn’t see ice but the temperatures in the lava tubes, heights up to 15 feet, were 20 to 30 degrees cooler than temperatures above ground. [Refer to the July issue of the Bulletin for directions to the above areas.] Learning some details concerning the local landscape helps to put things into perspective. Different compositions of the magma, dates of emplacement or eruption, glaciated features were just a few things considered by non-members Lisa Thomas and Wayne Muchmore and by Obsidians Bonnie Manheim, Gary Marx and Sylvia Harvey (trip leader). Special thanks to Lisa Thomas, a fellow geologist!


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