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Department of Science and Mathematics, Cedarville University, 251 N. Main St., Cedarville, OH 45314 USA
Dr. John H. Whitmore currently serves as Senior Professor of Geology at Cedarville University where he has been teaching since 1991 and started a young earth geology major in 2009 which has now produced more than 50 graduates. He is closely associated with Canyon Ministries and Answers in Genesis who sponsor annual raft trips in the Grand Canyon for which John teaches the geology. He has written widely, especially about the Coconino Sandstone. He served as editor of the ICC in 2018 and 2023.
Full Paper Presentation
The author and his colleagues have been working on the Coconino Sandstone (Arizona, USA) for more than twenty years concluding that the sandstone formed in an underwater setting instead of the conventionally accepted desert dune environment. During their work (Emery et al. 2011; Whitmore 2021; Whitmore and Garner 2018) they reported that average cross-bed dips in the Coconino were approximately 20°, consistent with what others have found in the Coconino (Maithel 2019; Reiche 1938). Most realize this average measurement is far less that the angle or repose for desert sand dunes, which is about 33-34°. The Coconino often lacks cross-bed dips in this range, leading to the erroneous conclusions by some, that cross-beds formed in subaqueous settings have shallower cross-bed dips than those found in eolian settings.
To address this problem, cross-bed inclinations of ancient sandstones and from modern eolian dunes were collected from the literature and from some from personal field measurements. Sandstones include the Coconino, Wescogame, Tapeats, Navajo, Manakacha, Esplanade, Cedar Mesa and Botucatú. Modern sand dunes include measurements from dune fields in Brazil, Uruguay, and New Mexico. The data set includes more than 5,000 measurements from each of these settings—76 dune field localities and 88 sandstone localities. Initial results and conclusions were presented in abstract form to the Geological Society of America meeting in Portland, Oregon (Whitmore 2021). This proposed paper will result in a full technical paper of my work on this subject.
Initial findings are that cross-bed dips from rocks and modern eolian dunes both have central tendencies near 20°. The difference in the data sets occurs in their standard deviations. The middle quartiles of sandstones occur between about 15 and 24 degrees with a standard deviation of 5.7. The middle quartiles of modern sand dunes occur between 9 and 27 degrees, with a standard deviation of 10.1, nearly double that of sandstones. In other words, modern sand dune angles have a much wider spread than sandstones. Additionally, modern dunes often have a significant number of measurements >30°, which is uncommon in sandstones formed in a wide variety of supposed depositional environments. A common argument from sandstones with an eolian interpretation is that cross-bed angles have been compacted from higher angles to lower angles to produce the smaller angle measurements found in sandstones. But this cannot be the case, because modern sand dunes also have an abundance of lower angles which are not represented in sandstones. Thus, this study demonstrates that the spread of cross-bed dip inclinations in sandstones is the important criterion that distinguishes them from eolian deposits, not the averages of their dips. Additionally, it was found, irrespective of presumed conventional depositional environment, that some sets of sandstone cross-bed inclinations cannot be statistically distinguished from one another in the case of the Grand Canyon’s Coconino (eolian), Wescogame (fluvial), and Tapeats (shallow marine) Sandstones. My hope is that we can use these types of measurements and comparisons to show that supposed examples of ancient eolian deposits like the Navajo and Coconino should be interpreted as subaqueous based upon the standard deviations of their cross-bed inclinations.
cross-bed dips, cross-bed inclinations, Coconino Sandstone, Tapeats Sandstone, Navajo Sandstone, eolian cross-beds, angle of repose, cross-bed statistics
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Whitmore, John H.
"Can Sandstone Cross-bed Dip Inclinations Determine Depositional Environment?,"
Proceedings of the International Conference on Creationism: Vol. 9, Article 27.
Available at: https://digitalcommons.cedarville.edu/icc_proceedings/vol9/iss1/27