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

Sand flow cross-strata are quite common in the [ancient] sandstones discussed here. Narrowly lenticular sand flow cross-strata, such as are common in small modern dunes of the Oregon and south Texas coasts (Hunter, 1977) and in some desert dunes (Sharp, 1966), are very rare in the [ancient] sandstones discussed here. Rather, the individual sand flow cross-strata typically extend many meters along the strike of the cross-stratification. In addition, the sand flow cross-strata of the ancient sandstones differ from those of modern small dunes by typically being in contact with other sand flow cross-strata rather than being separated from one another by grainfall deposits. The general absence of fadeout laminae (defined by McKee et al. 1971) within the sand flow cross-strata indicates that the flows became thoroughly mixed before coming to a stop. Structures indicative of slumping down a slipface are very uncommon in the sandstones discussed here (McKee, 1979, p. 192). We concur with Hunter that these structures are very rare. We did not locate any lenticular-like flows in the Coconino and we think the absence of such features in the Coconino and other sandstones is indicative of aqueous processes. We did find these features preserved in the sediments of numerous modern subaerial dunes that we studied (Fig. 22), but these features have not been identified in subaqueous dunes. Instead, subaqueous dunes tend to have very wide avalanche surfaces (Hunter 1985). Modern sand dunes that have been excavated have revealed a number of small-scale structures (McKee and Bigarella 1979b). We failed to find many of these features in the Coconino. Things that resemble some of these features are present, like overturned folds, but they are not laminae-scale or cm-scale features as illustrated by McKee and Bigarella 1979b; instead, they are meter-scale (like the parabolic recumbent folds). We did locate a number of low-amplitude ripples with crests parallel to slopes (Fig. 23) and features that were slump-like (Fig. 24). However, these kinds of ripples are known to occur in similar style on various sand waves and related subaqueous features (Houbolt 1968). The “slumps” may actually be slumps, but they cannot be explained in an eolian environment because the dips Whitmore and Garner ◀ The Coconino Sandstone ▶ 2018 ICC 596 Figure 19. Thin sections show there has been very little compaction within the Coconino Sandstone. This data rejects the hypothesis that the cross- beds of the Coconino have been significantly compacted in order to make the observed dips (averaging about 20º) much less than the angle of repose (about 33-34º). Also see Fig. 13 which shows no compaction of dolomite ooids.