It's kinda funny... these sit right off the highway and if you blink you'll miss them. We recently picked up a small book called: OREGON ROCKS! and liked it so much I contacted the author to see if she had another called: WASHINGTON ROCKS! - well, there is one but by another author albeit in the identical format (which we liked). So, when we travel, we try to check to see if there's any geological rocks of interest. For my 70th birthday (in 4 weeks) we'll be stopping by the
BIG OBSIDIAN FLOW.