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

Borsch, K., J.H. Whitmore, R. Strom, and G. Hartree. 2018. The significance of micas in ancient cross-bedded sandstones. In Proceedings of the Eighth International Conference on Creationism , ed. J.H. Whitmore, pp. 306-326. Pittsburgh, Pennsylvania: Creation Science Fellowship. THE SIGNIFICANCE OF MICAS IN ANCIENT CROSS-BEDDED SANDSTONES K. Borsch , Cedarville University, 251 N. Main St., Cedarville, OH USA 45314 John H. Whitmore , Cedarville University, 251 N. Main St., Cedarville, OH USA 45314 johnwhitmore@cedarville.edu (corresponding author) Raymond Strom , Calgary Rock and Materials Services Inc., #3, 3610-29 th St. NE, Calgary, Alberta, Canada T1Y 5Z7 rocktell@telus.net George Hartree , Cedarville University, 251 N. Main St., Cedarville, OH USA 45314 ABSTRACT The cross-bedded Coconino Sandstone is almost certainly within the stratigraphic range of the Flood, however it is commonly cited by conventional geologists as the classic example of an eolian deposit, and thus an argument against the scientific viability of the Flood. In our petrographic study of the Coconino Sandstone, we discovered muscovite mica (and sometimes biotite mica) in almost every thin section. This is surprising given that micas have not previously been reported in this, or any, “eolian” cross-bedded deposit. The mica found is detrital in character (i.e., it is not an alteration product) and thus is part of the primary depositional fabric. This led to the investigation of other cross-bedded sandstones from around the world, especially those of similar stratigraphic age, all of which have been conventionally interpreted as wholly or partly eolian– the same frequent occurrence of micas was observed. Previous laboratory experiments have provided some framework for understanding this discovery. Based on those experiments, it was found that mica cannot survive continuous transport much more than four days (or about 500 km) by simulated eolian processes, but can last for more than a year (or about 7,500 km) when transported continuously by simulated subaqueous processes. Field observations confirm that modern ergs contain virtually no micas, of any size, except in cases where mica sources (such as granite outcrops, beach sand or fluvial sand) are located in the immediate vicinity (~<10 km) of the erg. By contrast, the Coconino sand body and its correlative stratigraphic units stretch for many hundreds of kilometers across (with a total area of 2.4 million km 2 ), and therefore the interior of the deposit should be virtually mica-free if formed by eolian processes. We catalog and illustrate a large number of cross-bedded sandstones that contain mica grains (mostly muscovite) as an accessory mineral. The dominant conventional view is that these sandstones are eolian in origin, but experimental data and field observations suggest otherwise. The presence of micas in cross-bedded sandstones is a previously neglected criterion that can be used to argue for a subaqueous depositional environment for the formation of cross-bedded sandstones. KEY WORDS experimental mica abrasion, cross-bedded sandstones, muscovite, biotite, Casper Sandstone, Coconino Sandstone, Corrie Sandstone, Dawlish Sandstone, Glorieta Sandstone, Hopeman Sandstone, Locharbriggs Sandstone, Lyons Sandstone, Navajo Sandstone, Penrith Sandstone, Schnebly Hill Formation, Tensleep Sandstone, Weber Sandstone Copyright 2018 Creation Science Fellowship, Inc., Pittsburgh, Pennsylvania, USA www.creationicc.org 306 INTRODUCTION AND BACKGROUND Geologists have long suspected that eolian sands and sandstones should not contain mica, although little experimental or observational data is present in the literature to support this notion. Eolian dune environments are overwhelmingly dominated by the mineral quartz (having a hardness of 7.0 Mohs scale) and should rapidly abrade micas which are much softer (Mohs = 2.5) and have fragile sheets that easily cleave. Standard petrographic texts suggest mica should be found in subaqueous sediments, but not in eolian ones (Hallam 1981, p. 20; Mader 1983, p. 589, 590; Moorhouse 1959, p. 343; Tucker 1981, p. 45). This notion is so entrenched in the minds of some geologists that they proclaim the absence of mica in certain sandstones based only on their assumption that a particular sandstone is eolian (without doing any petrographic work! ). For example, Young and Stearley, in referring to the Coconino Sandstone in particular state (2008, p. 305): “Mainstream sedimentologists feel that the eolian, that is, wind-blown, nature of such sand accumulations [the Coconino Sandstone] is well founded. The very fine sand of these formations has a uniform grain size that is characteristic of wind-blown sand in general. The grains consist of resistant quartz. Less resistant mica grains and ultra-fine clay particles have been abraded to oblivion and /or wafted off site by wind (emphasis added).” Studying cross-bedded “eolian” sandstones is an important endeavor for creationists because many of these sandstones occur in Permo- Triassic rocks which are often sandwiched in between rocks that are generally agreed to be Flood deposits. Thus, sandstones like the Coconino and the Navajo have been used as prima facie evidence against the Flood. For example, speaking specifically about the Coconino Sandstone and eolian deposits in general, Strahler (1999, p. 217) states: “The evidence of subaerial origin of the dune-sand formations is undisputed as to its significance by mainstream geology; in itself is sufficiently weighty to discredit the biblical story of the Flood of Noah as a naturalistic phenomenon occurring in one year.” A wide variety of other skeptics, some theistic, have come to similar conclusions about these cross-bedded sandstones.