Saturday, January 12, 2013

Geo 365: Jan. 12, Day 12: Pillow Basalt

The margins of three basalt pillows, highlighting the void space between them. That void is filled with a mixture of basaltic glass (sideromelane and tachylite), palagonite (altered or weathered basaltic glass), and zeolites. The zeolites at this location are small- this isn't a good collecting spot for them- but to the extent they are identifiable, seem to be comprised mostly of analcime, natrolite and stilbite, in that order of abundance. Here is a post I never got around to actually finishing talking about pillow basalts and this spot in particular. Hint: this is the finest exposure of pillow basalts I've ever seen, and I've seen a lot of them. DON'T MISS! (if the opportunity arises)

Photo unprocessed. July 8, 2012. Lens cap is ~52 mm diameter. FlashEarth: Park here, even if gate is open (you could get locked in), then follow access road west/south-west, with a hook north at the end, to here. Pillows are on the west-facing wall of a defunct quarry.

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