Young-Earth creationists claim that the Paleozoic sedimentary rocks in the Grand Canyon and the Mesozoic sedimentary rocks of the Grand Staircase north of the canyon, in which Zion and Bryce Canyon National Parks occur, were deposited during Noah’s worldwide flood about 4,500 years ago (Hill 2002; Hill and Moshier 2009). I realize that readers of Skeptical Inquirer accept modern scientific views on this subject, but this examination of the creationist claims might be useful when communicating with others less imbued with scientific thinking.
There are at least twenty-one scientific reasons a worldwide flood recounted in the Bible cannot have happened.
1. The stair-stepped appearance of erosion of sedimentary rocks in the Grand Canyon with sandstones and limestones forming cliffs and shales forming gentle slopes cannot happen if all these rocks were deposited in less than one year. If the Grand Canyon had been carved soon after these rocks were deposited by a worldwide flood, they would not have had time to harden into solid rock and would have been saturated with water. Therefore, the sandstones and limestones would have slumped during the carving of the canyon and would not have formed cliffs (Hill et al. 2016).