---

• n  a fine-grained sandstone of consolidated silt

• Last May, while scrambling up the side of a butte, he noticed an unusually large pelvic bone and three sun-bleached vertebrae poking out of the siltstone.
• The whole trench is conveniently capped by a layer of impermeable siltstone a few hundred feet below the present surface.
• Instead, in geologists' lingo, it "disseminated" throughout the siltstone and limestone laid down by an ancient ocean.