Geology of Eastside Portland and Johnson Creek
/Moments after the election of the new GSOC board at our February 9th meeting, President-elect Paul Edison-Lahm addressed a near-record crowd with his presentation “An Amateur's Guide to the Geology of Johnson Creek and Eastside Portland.” He explained that since a creek cuts down through vegetation and construction into layers of earth otherwise unseen, the rocks in the creek can tell us the geologic history of the surrounding countryside. Grey basalts and dull orange quartizites, found in the Reed College Lake near his home for example, are clues to earlier epochs of catastrophic volcanism and icy inundation.
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