Figure 13. Progressive Flood model (diagrammatic) sea level curve and megasequences chart. The sea level changes shown are relative, therefore no scale is given. relied on geohistory analysis and biostratigraphic data and paleoenvironmental interpretations across selected continental margins. And of course, they used the uniformitarian environmental interpretations as a guide also. Their result shows the highest sea levels were reached in the Ordovician and in the Late Cretaceous. It is significant to note that Vail and Mitchum (1979) have acknowledged that their sea-level changes from the Cambrian through Early Triassic are not as well constrained as those from the Triassic upward. As mentioned above, their uniformitarian sea level curve is based on evolutionary, deep-time environmental interpretations of many sedimentary units. For example, most conventional geologists believe the Coconino Sandstone in the American Southwest was deposited on dry land, implying global sea level was lower during its deposition. In contrast, Whitmore et al. (2014) have demonstrated rather conclusively that the Coconino Sandstone was deposited under marine conditions. Therefore, sea level was likely much higher during its deposition (during the Absaroka megasequence) than what is shown on the uniformitarian sea level curve (Fig. 1). Some critics have tried to explain this apparent progressive flooding pattern as a product of differential erosion. They assume there was more erosion of the older stratigraphic units, and correspondingly, less erosion in the upper or younger layers. But is this really true? Or is it a merely a matter of the lack of depositional extent of the earliest megasequences? Snelling (2014b), discussing the paper by Holt (1996), acknowledged that there is a disproportionate amount of Cretaceous (Zuni, Fig. 11) and Tertiary (Tejas, Fig. 12) sediment preserved in the rock record globally, compared to earlier deposits (Sauk through Absaroka, Figs.7-10, and Table 1). However, Snelling (2014b) reasoned that it is impossible to know how much volume of the earlier megasequences may have been eroded and possibly redeposited as Cretaceous and Tertiary strata. As a consequence, he reasoned that the limited amounts of Sauk, Tippecanoe and Kaskaskia strata found across North America were likely greatly reduced by erosion during the later phases of the Flood. The values in Table 1 show that the Sauk, Tippecanoe and Kaskaskia megasequences consistently preserve the least total sedimentary volumes across all continents, compared to the three subsequent megasequences. Some of the volume data shown in Table 1 have undoubtedly been reduced by later erosion, but exactly how much is uncertain. In spite of this uncertainty, it is likely the Sauk megasequence has preserved at least a reasonable proportion of the original extent and possibly volume deposited because we see consistent patterns in the surface coverage of the Sauk, Tippecanoe and Kaskaskia megasequences on all five continents in this study (Figs. 7-9). Admittedly, it is difficult to determine exactly how much erosion may have occurred if the material is now presumably missing. But, if there were lots of earlier erosion that reduced the volume of all pre-Absaroka strata significantly, there should still be evidence to observe. Each continent shows a dramatic increase in volume and areal extent in the Absaroka megasequence (Fig. 10) and even more in the Zuni and Tejas megasequences (Figs. 11-12). In fact, if we look at a graph of the percent volume by megasequence for the five continents we see that the Zuni alone has 32.6% of the global total Phanerozoic sediment volume (the Tejas has 32.5%) (Fig. 14). Furthermore, the argument that all earlier strata were significantly reduced by erosion caused by mountain-building near the end of the Flood can be countered by several observations. First, the consistent internal stratigraphy of each megasequence testifies against significant erosion. Megasequences often start out with sandstone followed by shale and then carbonate rock. For example, the Sauk in North America still exhibits a complete cycle consisting of basal sandstone (Tapeats equivalent), followed by shale (Bright Angel equivalent) and topped by a carbonate (Muav equivalent). Vast erosion in between each megasequence cycle would have likely destroyed this systematic signature in many locations, if not totally. And yet we observe the complete sequence of sandstone, shale and carbonate in the Sauk megasequence across large portions of North America. Secondly, we do not observe significant numbers of reworked early Paleozoic fossils and mixed fossil debris in younger, Absaroka, Zuni and Tejas strata. Massive late Flood or post-Flood erosion should have transported vast amounts of fossil material and microfossils from the earlier megasequences, mixing them into younger sediments so that the fossil patterns would be less discernable in the later megasequences. This is not what is observed. The pattern of sudden appearance, stasis, and sudden disappearance of fossils is prevalent throughout the entire Phanerozoic sedimentological record, Sauk through Tejas (Wise 2017). Reworking significant amounts of fossils would likely have blurred this pattern. Third, there was a lack of Cenozoic mountain-building in Africa to erode and serve as a major source of Tejas sediment. North and South America have the Cenozoic-age Rocky Mountains and Andes Mountains, respectively. Europe has the Alps. Asia has the Himalayan Mountains and many smaller mountain chains. These uplifts served CLAREY AND WERNER Progressive Flood model 2023 ICC 423
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