Thin en echelon dikes in the Highline Community College erratic; AND a National Geo ‘erratics’ article

The granitic erratic at Highline Community College. Photo by Bud Hardwick.

Bud Hardwick sent photos and geographic information about a large granitic erratic (yes, another one of those dang things) at Shoreline Community College in Des Moines (Washington!). I looked closely at his photos and made some deductions about the geology. Take the virtual field trip to this erratic elsewhere on this website. The rock is notable because of the textbook en echelon dikes running the full length of the big erratic.

Also, the latest National Geographic has a photo essay on glacial erratics by Fritz Hoffman. Alas, none of the ones describe n this website or any others in western Washington are included, not even the Lake Stevens Monster, the largest in the whole country. See  the photos here (an NPR website).

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