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

are often noticed because they stand out compared to the tabular bedding that is so common. The ripples do resemble wind ripples which tend to have more rounded crests than most ripples found in subaqueous settings. We find no reason to believe that the ripples found in the Coconino could not have been formed in a subaqueous sand wave environment. Although much is not known about the fine-scale structures from large subaqueous sand waves, some observations have been made using radar and video. Lawrence Poppe of the United States Geological Survey claims that small ripples are present on the backs of megaripples which occur on the backs of larger sand waves in Long Island Sound, near New York City (personal communication, 2011; Poppe et al. 2006). Currents flowing over the tops of sand waves should produce lee vortices in much the same way as they are produced in eolian settings; this could possibly produce subaqueous ripples, depending on current velocity. Houbolt (1968) suggested currents could flow perpendicular to the flanks of large sand ridges on steep foreset slopes. Lundy (1973) used this idea to explain the parallel-to-dip ripples in a subaqueous Coconino model. H. “Mud cracks” Some have claimed that the polygonal crack-like patterns (Fig. 37) that can commonly be found on the tops of bounding surfaces are indeed desiccation cracks (Hill et al. 2016, p. 68). However, these cannot possibly be “mud” cracks because these features are in a clay-poor sandstone, not mud. In order for sediment to crack by desiccation it must be dominated by clay-sized particles and must have certain clay minerals. Even the Hermit Formation (which is dominantly a siltstone) does not have the right grain size and mineralogy to crack via desiccation (Whitmore and Strom Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 605 Figure 32. Sometimes “raindrop prints” form deep depressions into cm-thick slabs. This pair of images shows the bottom-side and top-side of the same cm-thick piece of rock. The underside has raised “dimples” that shows the pattern of the surface of the rock that was below this slab. The pattern is similar to the rows of “dimples” that we found on other rocks (see Figs. 25 and 36). The slab was a piece of float, so we only know the dip was in one of the directions of the double-ended arrow. The rows of dimples are associated with very low relief ripples. Some of the dimples on the top-side are about 7 mm deep. The patterns are not as clear, but they are also oriented in the same approximate direction as the layer below. If these were “raindrop prints” it seems the dimples would be in random patterns and not oriented. Furthermore, why would there be similar patterns on two closely-spaced surfaces? We hypothesize the “dimples” may be water or gas escape structures. Chino Wash, Arizona. JHW photos 2506-2018, 255-2018.