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

2010). Sand grains are usually too large and insufficiently cohesive to form cracks during desiccation (Lowe 1975). In our unpublished XRD studies of the Coconino, both weight and volume fractions of clay minerals were always less than about 2% and were often non-existent in the bulk powder results. The most common clays in the Coconino were kaolinite and illite. Modern soils that crack due to desiccation have significant amounts of clay. Basma et al. (1996), Harianto et al. (2008), Yassoglou et al. (1994) and Yesiller et al. (2000) report cracking in soils with clay contents ranging from 13 to 58.3% and silt contents ranging from 21 to 52%. The Coconino simply does not have the clayminerals necessary for any kind of desiccation to occur. The origin of the polygonal structures in the Coconino is not known; Leonard Brand has been thinking about these for some years (personal communication 2018; Peters and Brand 1999), but their origin is still a mystery. I. Sand injectites Whitmore and Strom (2010) argued that the sand-filled cracks found at the base of the Coconino and penetrating into the Hermit Formation cannot be desiccation cracks or large playa cracks because of the lack of abundance and types of certain clays necessary for desiccation cracks to be produced in the Hermit Formation. They argued the sand-filled cracks are injectites caused by the Laramide movement of the Bright Angel Fault. It is not unusual for clastic dikes, injectites, and sand volcanoes to occur coincident with faulting; fine-grained water-saturated sands are especially mobile (Hurst and Cartwright 2007; Ettensohn et al. 2002). Evidence that the Bright Angel Fault was responsible for the sand-filled cracks includes 1) the deepest sand-filled cracks occur next to the fault (>15 m in depth) and at its greatest offset (61 m, Fig. 43), and 2) the cracks decrease in length away from the fault and get shorter along places where the fault did not have as much displacement. Cracks disappear altogether far away from faults (Fig. 39). If the cracks were truly desiccation cracks we might expect random orientation of crack trends (instead they are oriented) and horizontal layering of crack fill as sand filtered down from above filling the cracks (instead the cracks are mostly massively bedded and some contain vertical “layering”). J. Parabolic recumbent folds Whitmore et al. (2015) argued that large deformation features found in the Coconino and Toroweap Formations near Sedona and in the Coconino in Wupatki National Monument are penecontemporaneous parabolic recumbent folds (Fig. 40). If these were slumped eolian dunes as McKee and Bigarella (1979a, pp. 201-202) argued, or groundwater deformation features as commonly found in the Navajo Sandstone (Bryant and Miall 2010) the deformation would cross through bounding surfaces and have limited horizontal extent. Instead, the folding we found in Sedona is confined to individual cross-bed sets (proving its penecontemporaneous nature with the cross-beds) and extends for at least 400 m on Brins Ridge and for at least 50 m on Lizard Head in a regular pattern (showing that these features are not slumped eolian dunes). The mechanism of parabolic recumbent fold formation may be one or a combination of four causes (Whitmore et al. 2015), all of which take place during active Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 607 Figure 35. Raindrop prints in modern sand usually produce a mottled-like surface, not a cratered surface as one would expect. This sand was nearby some dried and cracked mud, which had the more typical raindrop prints in it (inset photo). Pocketknife insignia is about 1 cm long. JHW photo 3229-2010 and 3222-2010 (inset). Figure 36. Ripples in the Coconino are often associated with parallel rows of crater-like features that some may have identified as “raindrop prints.” As are the ripples, these features are parallel to dip. The underside of this slab has been placed on edge so sunlight could better highlight the features. Ash Fork Area. JHW photo 3434-2014.