National Geographic : 1924 Jan
THE NATIONAL GEOGRAPHIC MAGAZINE NATURAL OPENING TO CARLSBAD CAVERN FORMED BY THE COLLAPSE OF THE ROOF The rocks which once filled this space now lie on the floor of the cave, 170 feet below the surface. The scale is shown by the man standing beyond the opening. k'fotograpns by wv 11s i. l,ee A SINK-IIOLE WHERE BEDS OF ROCK-SALT AND GYPSUM UNDERLIE THE SURFACE This hole, 75 feet across and 60 feet deep, was formed in August, 1918, when a cavern collapsed. A part of the material from this hole now rests in a conical mound on the floor of the cavern; other parts have been distributed through subterranean passageways to find lodgment-who knows where?