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

Baumgardner, J. 2018. Understanding how the Flood sediment record was formed: The role of large tsunamis. In Proceedings of the Eighth International Conference on Creationism , ed. J.H. Whitmore, pp. 287–305. Pittsburgh, Pennsylvania: Creation Science Fellowship. UNDERSTANDING HOW THE FLOOD SEDIMENT RECORD WAS FORMED: THE ROLE OF LARGE TSUNAMIS John Baumgardner , Logos Research Associates, 24515 Novato Place, Ramona, CA 92065, johnrbaumgardner@gmail.com ABSTRACT A daunting 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 applies numerical modeling to explore the question of whether repetitive giant tsunamis generated by catastrophic plate tectonics during the Genesis Flood can plausibly account for the Flood sediment record. The modeling suggests with reasonable parameter choices that tsunami-driven erosion during the Genesis Flood can produce considerable volumes of new sediment, 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. The model incorporates a representation of the dynamic history of the continental blocks to explore the consequences of continental motions. It also includes an initial continental topography, with low elevations along the coasts and higher elevations inland. This computational study provides important insight regarding the primary source of the Flood water, how that water was able to cover the normally high-standing continent surface, what produced and sustained the water flow, primary sources of the sediment, primary means of sediment transport and deposition across the continent surface, why so little erosional channeling occurred between sediment layers, processes responsible for observed paleocurrent directions, and mechanisms responsible for the abundance of planar erosional features at many scales. It is vital to stress that the exploration described in this paper is still exceedingly limited in its realism relative to the actual earth and includes only a restricted subset of the processes in operation during the Flood cataclysm. Despite the limitations, it suggests strongly that tsunamis likely played a key role in producing the fossil-bearing sediment record we observe today. KEY WORDS Genesis Flood, giant tsunamis, catastrophic plate tectonics, turbulent sediment transport, open channel flow, cavitation erosion, shallow water approximation Copyright 2018 Creation Science Fellowship, Inc., Pittsburgh, Pennsylvania, USA www.creationicc.org 287 INTRODUCTION A central 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. Some of the prominent issues are the source of the Flood water, how that water came to cover the normally high- standing continent surface, the sources of the sediment, the nature of the water flow that transported and deposited the sediment across the continent surface with surprisingly little erosional channeling of the sediment layers, the mechanism responsible for producing and maintaining that water flow, the cause for the abundance of planar erosional unconformities at many scales in the sediment record, and where the Flood water went at the end of the cataclysm. The daunting complexity of this task prompted the author about seven years ago to pursue a numerical modeling strategy in a beginning attempt to address the task. Two previous papers (Baumgardner 2013; Baumgardner 2016) have documented the mathematical underpinnings and numerical methods in moderate detail. In brief, the approach is to solve for the water flow across the earth’s surface utilizing what are known as the shallow water equations that enforce conservation of mass and a balance of forces on each cell in the computational grid. The shallow water equations are a version of the standard Navier-Stokes equations for fluid flow that make the simplifying assumption that fluid depth is small compared with the horizontal scales of interest. The shallow water equations allow one to treat the water as a single layer with laterally varying surface height above laterally varying bottom topography. In addition, over continental regions, where the water depths are much smaller relative to the deep ocean and where turbulence can be expected to arise because of high water velocities, the equations of open channel flow are solved to track the suspension, transport, and deposition of any sediment present. Erosion is treated assuming that cavitation is the dominant mechanism under the conditions that prevailed during the Flood. 1. Potential causes of the water motion during the Flood Even with all this numerical machinery in place and working, a prominent issue remains, namely, what was it that drove the water motion? In the investigations leading to the Baumgardner (2013) paper, several possibilities were explored, including bolide impacts in the ocean, torque from a close approach of a planetary body, and the tidal effects of such a close encounter. Of these three possibilities, it was found that only the third can drive the water flow strongly enough and over a large enough fraction of the earth’s surface to generate sufficient sediment and distribute it over the land surface in any sort of pattern that might bear some resemblance to the actual sediment record. Even in that case it was necessary to postulate multiple near approaches, presumably by the same extraterrestrial body, during the time span of the Flood.