[masraum]

Originally Posted by daepp

Devil's Postpile, on the eastern Sierra, not far from Mammoth. Hike down their with my little boy on my back circa 1996. As soon as I saw your shot, and all those hexagons, I knew that had to be basalt. I don't know the "why", but I was pretty wure "what"!

I think columnar basalt is not uncommon anywhere there's been volcanic activity. I've seen it in the cascades in Washington. And many/most of us are probably very familiar with...