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

metamorphosed Coconino occurs in southwestern Arizona near Quartzite (Miller and McKee 1971). Some preliminary and ongoing work of this project is to correlate the Coconino beyond the borders of Arizona (Whitmore 2016). Figs. 3 and 4 show our preliminary map of the areal extent and thickness of units that are very close in age and character to the Coconino. 2. Petrology A. General petrology In most locations the Coconino is a fine-grained quartz arenite, containing about 90% quartz/chert and 10% orthoclase and other accessory and trace minerals. Mean grain size ranges from about 3.45 ϕ in northern Arizona to about 2.75 ϕ in central Arizona (Figs. 5 and 6). The sandstone is more poorly sorted in northern Arizona compared to central Arizona (Figs. 7 and 8). The sandstone in Whitmore Canyon (WC) is very poorly sorted (standard deviation = 0.94) compared to the sandstone at Cave Spring Campground (CSC) which is well sorted (standard deviation = 0.50). We found that the Coconino is sub-angular in northern Arizona and sub- rounded in central Arizona (Figs. 9 and 10). Whitmore et al. (2014) discusses the petrology and mineralogy of the Coconino in greater detail. B. Dolomite Dolomite occurs in four different modes in the Coconino over a relatively large area (Fig. 11). It occurs as beds (Fig. 12), as ooids (Fig. 13), as cement and rhombs (Fig. 14) and as large clasts, often orders of magnitude larger than the surrounding quartz grains (Figs. 14 and 15). C. Muscovite In nearly every thin section of the hundreds of thin sections we cut of the Coconino, we found muscovite mica as a trace mineral (Fig. 16). Also see Borch et al. (2018). D. Orthoclase Orthoclase (K-feldspar) usual- ly comprised about 10% of the sandstone (Fig. 17). Surpris- ingly, it is often more angular than the harder quartz sand (orthoclase = Mohs 6, quartz = Mohs 7). Alos see Whitmore and Strom (2018). E. Zircons Analysis of zircons contained within the Coconino Sandstone indicates that many of them were probably derived from the mid-Proterozoic rocks of eastern North America (Gehrels et al. 2011). F. Frosting In the few samples that we examined with the SEM, we found that quartz grains exhibited “frosting” (Fig. 18). G. Compaction Typical thin sections of the Coconino show little or no evidence of compaction (Fig. 19), except in sand injectites and a roughly 0.5 m-thick Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 584 Figure 4. Thickness of the Pennsylvanian-Permian sandstone sheet that can be correlated as more or less continuous in the western United States that includes the Coconino Sandstone (in Arizona). Preliminary work by Whitmore (2016). Not all units are shown on the map.