the tsunamis generated in a repetitive manner, every 60 minutes at a given location along active subduction zones. Such waves propagate at a speed of 200 m/s in the deep ocean. Plots (c) and (d) display the cumulative depth of crystalline bedrock erosion. As might be expected, the most intense erosion is occurring along the continent margins where the tsunami waves encounter the abrupt topographic change from deep ocean to continent. Plots (e) and (f) show the cumulative amount of sediment deposition of all sediment sizes. Regions of thick deposition generally occur in a band just inland from the coast. It is noteworthy that already at this stage in the simulation these zones in the coastal lowlands display sediment thicknesses of more than 300 m. At 20 days the average depth of bedrock erosion over the entire continent surface is 125 m. The average depth of sediment accumulation is 123 m, and the average amount of sediment in suspension is 2.2 m, where the averages are over the entire continental surface area. In all these plots the displacements of Laurentia, Baltica, and Siberia away from the remainder of Pannotia are evident. Fig. 8 provides plots at 50 days of water/land surface height, cumulative depth of bedrock erosion, net cumulative depth of deposited sediment. By this stage in the calculation, Baltica and Laurentia have reversed direction and collided with each other, resulting in the Caledonian orogeny. That block has in turn collided with Gondwana, producing the Variscan/Hercynian/ Appalachian orogeny. Those prominent mountain belts are expressed in the model as enhanced topography in those continent collision zones. Siberia has also collided with Baltica and Laurentia such that Siberia, Baltica, Laurentia, and Gondwana are now all joined together in a manner very similar to their earlier locations in Pannotia. Notably, the portion of continent that is to become eastern Asia has broken away from what earlier had been northeastern Pannotia and is now moving northward. At this point in the calculation the south rotational pole has moved to approximately 50° south latitude (marked by S on the equal area plots) along the zero-longitude meridian. Plots (e) and (f) show that sediment continues to accumulate in the zones adjacent to the coasts and that the zones are tending to expand inland. At 50 days the average depth of bedrock erosion over the entire continent surface is 343 m. The average depth of sediment accumulation is 340 m, and the average amount of sediment in suspension is 3.4 m. Fig. 9 displays the water/land surface height, the cumulative depth of bedrock erosion, and the net cumulative depth of deposited sediment at a time of 80 days. At this stage in the calculation, the east Asia block is near to docking with the Siberian block. That docking, which occurs at 90 days, will complete the assembly of Pangea. At 80 days there are regions where sediment thickness has reached well over 1,500 m. On average there is 581 m of erosion, 573 m of sediment over the land surface and 7.9 m of sediment in suspension. Fig. 10 displays, at a time of 120 days, water/land surface height, cumulative depth of bedrock erosion, and net cumulative depth of deposited sediment. At this point in the calculation, the Pangean supercontinent is beginning to break apart. The present North Atlantic Ocean is opening as the northern portion of Pangea consisting of Laurentia and Eurasia rotates clockwise relative to Gondwana. The Gondwana block itself is beginning to rift apart along the eastern margin of what today is Africa. At this stage in the calculation the rotation axis matches today’s orientation. The total volume of eroded sediment at this point is equal to an average of 825 m over the entirety of the continental surface. Fig. 11 displays the same fields at a time of 160 days. At this point Gondwana has disassembled fully into blocks corresponding to South America, Africa, Madagascar, India, Antarctica, and Australia, and Laurentia has split away from Eurasia in the north. The average amount of sediment deposited on the continent surface is now 1225 m. Fig. 12 displays the same fields at a time of 200 days. The continents are close to their current locations Water speeds are now small. The average amount of sediment deposited on the continent surface is 1486 m. From these plots the vast amount of sediment being eroded from the continent margins and being suspended and transported into the continent interiors by the highly turbulent water is readily evident. Fig. 13 provides a more rapid sequence of snapshots to illustrate how a large pulse of water invades the continent up its sloping topography and then drains away leaving its sediment load behind. Fig. 14 provides a comparison between the sediment distribution produced by this numerical model and the sediment distribution across the earth’s surface today. To the authors, the overall agreement is astonishing. For example, apart from a zone across its north, Africa is largely barren of sediment. Similarly, India, northeastern Antarctica, western Australia, eastern South America, and northeastern Europe also display a paucity of sediment. V. DISCUSSION A. A big picture approach Of necessity almost any attempt, and certainly this one, to model and understand how the Flood sediment record was generated during the global Genesis Flood must be a ‘big picture’ approach. As mentioned in the background section, one of the most acute challenges in this enterprise is accounting for the extreme rate of sediment erosion, transport, and deposition required, which is 12 m, or 40 feet, per day on average of the entire continental surface of the earth. The authors conclude that this numerical model demonstrates to a reasonable degree of confidence that the mechanism of tsunamidriven water flow as a consequence of catastrophic plate tectonics is able to account for such a high rate of sediment creation, transport, and deposition. The authors view this as the paramount ‘big picture’ result that we desire to communicate in this paper. Another result we deem as significant is the sediment distribution pattern that the model produces. As summarized in Fig. 14, there is a notable similarity between the pattern of sediment distribution generated by the numerical model and the observed pattern of sediment distribution on the continents today. As to an explanation, it appears that this agreement in some measure reflects proximity to a coastline and hence to exposure to intense tsunami activity and the duration of that proximity. As such, this explanation relies to a significant degree on the validity of the motion history assumed for the continents. A further result that bears emphasizing is that the sediment is on top of the continents, which themselves stand some 4,000 m above the BAUMGARDNER AND NAVARRO Large tsunamis and Flood sediment record 2023 ICC 376
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