The Proceedings of the Eighth International Conference on Creationism (2018)

light. Displayed in the figures are micas from seventeen different sandstones and from thirty-seven different locations. It is important to note that we have many more thin sections with mica than are shown in the figures. Detrital (not diagenetic) micas appear to be ubiquitous in the Coconino and in the other cross-bedded sandstones studied here. DISCUSSION In order to determine whether a sandstone was deposited in an eolian or subaqueous environment, a wide variety of criteria can be used. Mader (1983, p. 589) lists criteria that can be used to determine if a deposit is eolian or fluvial: 1) stratification, 2) composition, 3) intercalations, 4) transport directions, 5) petrography and texture, 6) deformation and 7) “miscellaneous.” In the “petrography and texture” section for eolian deposits, the “absence of mica” is the very first thing listed, along with rarity of authigenic tourmaline and rutile, weak lithification by slender quartz overgrowths, abundance of nest burrows of recent solitary bees, high textural and mineralogical maturity, and frosted grain surfaces. In the list of criteria for fluvial deposits (p. 590), the first characteristic listed is the “presence of mica.” However, our review of the literature suggest that sandstones are not identified as eolian or subaqueous based on a comprehensive list of criteria, but only a few factors, which often do not include petrographic study. The most commonly used criteria for identification of eolian deposits are large-scale foreset beds (stratification), steep cross-bed slopes (stratification), frosted grains (petrography), exceptional sorting (petrography), fine to medium sand (petrography) and several other characteristics (see McKee and Bigarella 1979). Even these criteria, however, are not always carefully examined before reaching an “eolian” conclusion. For example, Whitmore et al. (2014) and Whitmore and Garner (2018) found that the commonly cited criteria for eolian deposition of the Coconino Sandstone were not substantiated by petrographic study or extensive field work. Some authors claim “eolian” status can be “easily verified” with only precursory examination. For example, Young and Stearley state (2008, p. 215)” A hiker along one of the [Grand C]anyon’s many trails can easily verify that the Coconino Formation (sic) is composed almost entirely of very pale sand grains of a uniform size,” but careful petrographic study has determined that the Coconino Sandstone is on the whole poorly to moderately sorted (not uniform grain size; see Appendix I). Even in the latest, most comprehensive report of the Coconino by Middleton et al. (2003), petrology and detailed sedimentology are not demonstrated–they are only assumed. This paper highlights one of the criteria listed by Mader (1983), Borsch et al. ◀ Micas in ancient sandstones ▶ 2018 ICC 316 Figure 9. Micas from the Lyons Sandstone of Colorado and the Tensleep Sandstone of Wyoming. LSS-02 is view with cross polarized light. The photographs are oriented so that “up” is also the top of the photograph.