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

Examples include Helble (2011), Hill et al. (2016), Ranney (2001), Weber (1980) and Young and Stearley (2008). Two of the present authors (Strom and Whitmore) have been studying the Permian cross-bedded Coconino Sandstone for some time, along with other similar sandstones (see Whitmore and Garner 2018, in these proceedings). They discovered muscovite as a trace mineral in nearly every one of the hundreds of thin sections that they analyzed (Whitmore et al. 2014). As part of the same study they also investigated other cross-bedded sandstones in western North America and Great Britain and found many micas in these deposits as well. During a larger study of the Coconino, we also collected sand samples from along the California and Oregon coastline and compared those samples with coastal dune samples from the same location (Whitmore and Strom 2017). We also collected and studied a number of sand samples from inland dune locations in the western United States. We found that mica was conspicuously absent from dune samples, unless those dunes were in close proximity (less than tens of kilometers) from mica-bearing bedrock, stream (fluvial) sediments or beach sands. In studies of sand transport along the southwestern coast of Africa, Garzanti et al. (2012, 2015) found that the composition of sediment transported for hundreds of kilometers along the coastline (which contained micas) did not appreciably change. However, when the beach sand was picked up by wind and transported to the Namib dunes, all minerals became quickly rounded and the mica either disappeared or possibly was never transported to the dunes. To investigate the durability of mica in experimental eolian and subaqueous environments, Anderson et al. (2017) devised a series of experiments (also Anderson et al. 2013). To simulate an eolian transport environment, a small amount of muscovite-rich sand was placed in a one-gallon glass jar with an RC airplane propeller attached on the inside of the lid. The velocity of the propeller was adjusted so that a small “dune” slowly migrated around the bottom of the jar. After just four days of continuous transport in this apparatus, virtually all micas had been pulverized such that they could not be found in thin section, except where small (<100 µm) grains had become wedged inside the crevices of quartz grains, which effectively preserved them from abrasion; this transport time corresponded to roughly 500 km of linear transport. To simulate a subaqueous transport environment, the same mica-rich sand was placed in glass jar and laid on a rock tumbler assembly, which sustained a lateral dune. Surprisingly, after one year of continuous operation (roughly 7500 km), not only did the sand still contain an appreciable number of muscovite grains, but they were large enough to be seen with the naked eye. This can potentially be explained by a cushioning effect of the water, which has a much higher viscosity than air and reduces the kinetic energy of grain-grain collisions, thereby preventing the rapid degradation of mica and other softer minerals. Despite the simplicity of these experiments, they confirm our field and experimental observations that mica is rare in modern eolian deposits and commonly present in subaqueously deposited sands. The experiments of Marsland and Woodruff (1937) further confirm our observations. In their experiments with the abrasion of gypsum, calcite, apatite, magnetite, orthoclase, quartz and garnet sand, they noted that although there are many factors that probably effect rounding rates, softer minerals round much more rapidly than harder minerals during experimental eolian transport. There are significant implications for the discovery of appreciable quantities of mica in supposedly eolian sandstones. Only two environments are commonly known to produce cross-bedded sandstones: eolian and subaqueous. Both experiments and observations suggest that wind transportation rapidly degrades mica, while water transportation can preserve mica, perhaps almost indefinitely. Thus, when micas occur in a cross-bedded sandstone (such as Coconino Sandstone) it is likely a good indicator of its depositional environment. For this purpose, we here catalog and illustrate a large number of cross-bedded sandstones that contain mica (mostly muscovite) as an accessory mineral. METHODS This project is part of the Coconino Sandstone FAST project (Whitmore et al. 2012; Whitmore and Garner 2018) and included sandstone samples (primarily Permian) collected from the Coconino Sandstone (Arizona), Casper Sandstone (Wyoming), Cedar Mesa Sandstone (Utah), De Chelly Sandstone (Arizona), Glorieta Sandstone (New Mexico), Lyons Sandstone (Colorado), Navajo Sandstone (Utah), Schnebly Hill Formation (Arizona), Tensleep Sandstone (Wyoming), Weber Sandstone (Utah) and White Rim Sandstone (Utah). European samples included the Bridgnorth Sandstone (England), Corrie Sandstone (Scotland), Yellow Sand (England), Dawlish Sandstone (England), Hopeman Sandstone (Scotland), Locharbriggs Sandstone (Scotland) and the Penrith Sandstone (England). While we collected rock samples from all of these formations, we have vastly more sample material from the Coconino. Appendix I gives the conventional geological age, who identified the formation as eolian, and a few notes and references about each formation. Appendix II is a catalog for all of the individual samples chosen for use in this manuscript along with their approximate collection coordinates. The Coconino Sandstone primarily outcrops in northern Arizona and extends into other states as the same sand body, but with different names. Whitmore (2016; Figure 1) has done some preliminary correlation which shows the Coconino sand body can be correlated over many of the western United States with a surface area of approximately 2.4 million km 2 . Thus, the Coconino and many of the other Pennsylvanian and Permian sand bodies in the western United States are closely related to each other. After the samples were collected, they were made into thin sections (30 micron thickness) and stained using two methods. Double carbonate stain (potassium ferricyanide and alizarin red S – red stain for calcite, purple stain for ferroan calcite and blue stain for ferroan dolomite) was used to distinguish carbonate types. K-feldspar stain (yellow stain using HF etch and sodium cobaltinitrite indicator) was used to identify potassic feldspars in order to isolate them from other clear grains such as quartz. This work was done at Calgary Rock and Materials Services Inc. in Calgary, Alberta. Most microscope work was completed at Cedarville University with a Nikon Eclipse 50i Pol microscope equipped with the Br software package. RESULTS The results of this study are presented as a series of figures (Figs. 2-10) showing many examples of micas (primarily muscovite) in many different sandstones from the western United States and Great Britain. The photographs are grouped roughly by location. In these photos, blue is pore space (the empty space between grains and which has been impregnated with epoxy), white is quartz or chert, red is calcite and yellow is K-feldspar. Micas are evidenced by their recognizable edge-wise cleavage into thin sheets and high birefringence (rainbow-like appearance) under cross polarized Borsch et al. ◀ Micas in ancient sandstones ▶ 2018 ICC 307