4-21-jointing@river_ig2

Thanks! I've got much better examples of columnar jointing in basalt--some are in my Geology-Basalts album. This was a basalt flow, now mostly eroded away, that flowed along the lower Grand Canyon for a ways. I thought of this pic as a "family'n'friends" archive unlikely to be of interest to anyone else; otherwise I'd've cropped the tag on the right! ;)