Sunday, March 2, 2014

Geo 730: March 2, Day 426: Platy Jointing I

Platy jointing along Doherty Grade. Hammer in lower center for scale. As I mentioned two or three days ago, I'm not sure what kind of rock this is; it's too fine grained to get any sense of mineralogy. On a stop here with Anita Grunder, a volcanologist with OSU, she assessed it as basalt. She's certainly much more qualified and experienced than I am in these matters, but I'm not convinced. There's something about the way it rings that just isn't "basalt-like." It seems to me it's too felsic for basalt. However, the only way to be sure would be to run the chemistry- I suspect it's too fine grained to get a good idea of its composition petrographically- and that is not something I'm in a position to do.

Photo unmodified. August 19, 2011. FlashEarth Location.

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