"pumiceous," meaning pumice-like. On yet still another hand, though, the general public, for whom these signs are intended, would either read the two words as synonymous, be confused by the distinction, or throw their hands up in exasperation: "Oh, those scientists and their terminology!"
I'm inclined to let this bit of subtle pedantry slide.
Photo unmodified. August 21, 2011. FlashEarth location.
Is This Your Hat?
2 years ago