A major challenge for Flood geology is providing a credible explanation for how the staggering volume of fossil-bearing sediment was eroded, transported, and deposited in orderly patterns on the surface of the normally high-standing continents in only a few months’ time. This paper builds upon the numerical modeling work reported at the 2018 ICC (Baumgardner 2018b) utilizing a code named MABBUL which showed that repetitive giant tsunamis generated by catastrophic plate tectonics (CPT) during the Genesis Flood can plausibly account for the Flood sediment record. That modeling demonstrated that, with reasonable parameter choices, tsunami-driven cavitation erosion during the Flood itself, mostly along the continent margins, can produce most of the sediment in today’s fossil-bearing record. The modeling showed further that tsunami-driven pulses of turbulent water can transport this sediment vast distances across the continental surfaces and that these hydrological processes generate sequences of laterally extensive layers often separated by erosional unconformities. That model included a realistic time history of the continental blocks to explore the influence of continental motions on the overall patterns of erosion and sedimentation. It also included an initial continental topography, with low elevations along the coasts and higher elevations inland. Astonishingly, but not mentioned in that paper, the large-scale sediment distribution pattern generated in that model matched remarkably well the large-scale features of the actual sediment distribution of today’s world. This paper includes a more accurate continent motion history and runs at double the horizontal spatial resolution with grid points spaced only 60 km apart. It makes a beginning attempt to model the processes responsible for the megasequence structure of the Flood sediment record. It assumes that the erosional unconformities between the megasequences were caused by abrupt drops in global sea level, which in turn are assumed to be expressions of episodes of rapid cooling of the ocean lithosphere. The revised version of MABBUL, in addition to offering new insight concerning the megasequences, continues to yield a large-scale sediment distribution pattern that matches the observed pattern remarkably well. ABSTRACT I. INTRODUCTION Panoramic views of the sediment layers that blanket the continents as displayed in the Grand Canyon, for example, reveal a radical contrast between erosion and sedimentation regimes of the past and what prevails today. Fig. 1, a photo from the south rim of the Grand Canyon, reveals a layer-cake style of sedimentation with hundreds of distinct individual layers with vast lateral extent, almost uniform thickness, and boundaries between successive layers that are nearly smooth. These features are not atypical but typical of the global Phanerozoic sedimentary record as documented by numerous surface exposures and by tens of thousands of well logs from wells drilled into the subsurface for the purpose of petroleum exploration and production. By contrast, the higher elevation portions of the continental surface today are strongly sculpted by erosional processes and dissected by erosional channeling. Sedimentation generally is localized, mostly to stream and river channels and deltas. Given that erosional features are so prevalent across the continental surfaces today, why are they so infrequent on the strata boundaries in the underlying sediment record? Moreover, cross-bedding is common within individual layers throughout the record. Cross-bedding in a water-deposited sediment layer requires relatively high water speeds that produce migrating dunes, with sediment deposition on the front side of the dunes where the local water velocity becomes small because of the eddies that form there. The fact that these cross-bedded layers commonly display large horizontal extent, up to hundreds of km, transverse to the flow direction means that the water flow is sheetlike in character. There is no analogous process occurring on the continents today. A crucial question begging for an answer is what sort of process could conceivably drive and sustain relatively uniform high-speed water flow over such vast areas on the continental surface and do so repeatedly to account for many cross-bedded layers throughout the vertical column? Another point of contrast between geological processes occurring today relative to those of the past pertains to the preservation of distinct sedimentary layers. Because burrowing organisms are so John R. Baumgardner, School of Engineering, Liberty University, Lynchburg, Virginia, jrbaumgardner@liberty.edu Evan Navarro, Delta Star, Inc., en8hb@virginia.edu © Cedarville University International Conference on Creationism. The views expressed in this publication are those of the author(s) and do not necessarily represent those of Cedarville University. 9th 2023 Baumgardner, J., and E. Navarro. 2023. The role of large tsunamis in the formation of the Flood sediment record. In J.H. Whitmore (editor), Proceedings of the Ninth International Conference on Creationism, pp. 363-386. Cedarville, Ohio: Cedarville University International Conference on Creationism. THE ROLE OF LARGE TSUNAMIS IN THE FORMATION OF THE FLOOD SEDIMENT RECORD KEYWORDS Genesis Flood, Flood sediment record, large tsunamis, catastrophic plate tectonics, turbulent sediment transport, open channel flow, cavitation erosion, megasequences
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