National Geographic : 1924 Mar
AMONG THE "CRATERS OF THE MOON" 313 "THE BRIDGE OF TEARS" This natural bridge of solid lava doubtless covered an underground cavern at one time. It has a 50-foot span, and the height from floor to roof of arch is more than 15 feet. West of this bridge is a cave, where the author discovered fresh bear tracks, but no live animals were seen. EXAMINING VOLCANIC BOMBS Most of the lava bombs on Big Cinder Butte resemble footballs, with projections, or "ears," at each end. Some are compact throughout; others have an outer crust, sometimes an inch thick, of black basalt. The shape assumed by the liquid lava before cooling depended upon the length of time it was in the air and on the manner in which it rotated.