Seven Misconceptions about the Coconino Sandstone, Grand Canyon, Arizona
The Coconino Sandstone of the Grand Canyon area of Arizona is one of the few rock formations that are often used as convincing evidence against the Genesis Flood. Many claim it represents fossilized desert sand dunes. The sandstone is noted for its large high-angle "cross-beds" that supposedly formed as dry sand avalanched down slopes on sand dunes. Based upon a multi-year study, seven widely held misconceptions about the character of the sandstone were uncovered: (1) It has steep cross-bed dips at the angle of repose. (2) It has well-rounded and well-sorted sand grains, just like those of modem sand dunes. (3) As the Coconino Desert formed, it filled open mud cracks on a dry floodplaln. (4) Vertebrate footprints In the Coconino were made by animals walking on steep desert sand dunes. (5) Raindrop prints can commonly be found in the sandstone proving its subaerial origin. (6) The sand grains of the Coconino are "frosted", meaning their surfaces have been damaged by multiple grain-to-grain collisions while being blown about in a desert. (7) Large contorted beds in the Coconino represent slumped sand dunes. Contrary to these common claims, our research has found (1) crossbed dips of 20° not 32°, (2) subangular and moderately sorted sand, (3) sand injectites at the base of the Coconino (not mud cracks), (4) evidence the vertebrates were making tracks underwater, (5) the "raindrop prints" do not resemble modern prints, (6) the sand grains are chemically, not mechanically, frosted, and (7) the large folds have the characteristics of parabolic recumbent folds that are known to be produced by strong subaqueous currents. These discoveries, along with some other evidences that we have found, are suggestive that this sandstone was deposited underwater, not in a desert. Our current hypothesis is that the Coconino represents a subaqueous sand wave deposit. Such deposits are quite common today on continental shelves with strong ocean currents.
John Whitmore. "Seven Misconceptions about the Coconino Sandstone, Grand Canyon, Arizona" The Research and Scholarship Symposium. Cedarville, OH. Apr. 2013.
Available at: http://works.bepress.com/john_whitmore/18