VIVIENNE, JOHNNY AND Val shepherded Danny through the first narrow entrance made of marine deposits left eight hundred million years ago, sedimentary rock called Noonday dolomite, rock that was one thousand feet thick. Once, down in quiet seas, there were vertical tubes through which the rotting algae at the bottom of the water sent up carbon dioxide, venting the marine rot upon the rocks. Now the quiet seas were quiet canyons. This first passageway was wide enough for only one person. It rose high on both sides, smooth and shiny, made of marble. The Noonday dolomite and the mosaic breccia had formed in a seabed, and under pressure the rock became a masterful mosaic, cliffs of it, and narrow dry falls you inched through, and climbed up and down rocks through. Whereas the testing grounds an
