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

behind erosional surfaces at the top and base of the megasequences and changed the rock type abruptly (called xenoconformities, Carroll 2017). These major shifts in depositional architecture are recognizable and traceable across continents and offshore alike using distinctive characteristics observed on seismic reflection data, such as abrupt truncations and strong reflecting horizons. Because this method concentrates on the changes in the physical attributes of the rocks, it is less dependent on the fossil record for correlations (Sloss 1963). 2. Construction of basal lithology maps Of particular interest were the basal rock types in each megasequence, deposited as the ocean water transgressed across the continents. The basal rock types were most likely the best preserved of any interval within each megasequence as all subsequent erosion from regressive phases eroded from the top of the megasequence down. That is not to say that all the basal rocks in each megasequence were preserved because the regressive phase may have removed all of the preceding megasequence rock in some locations. Accordingly, maps of the basal rock type in each megasequence and stratigraphic cross sections were constructed that allowed continent-scale correlations of the basal stratigraphy for each megasequence. 3. Construction of maps of unique sediments of semi-regional extent We also compiled maps of distinctive rock types, like bedded chert layers and salt and gypsum-rich layers, keeping track of each by megasequence. These unique lithologic units also allowed us to test our megasequence boundary picks on a regional scale. For example, we assumed megasequence correlations were validated if the salt-rich or chert-rich layers remained in the same relative location within the megasequences, from column to column, and did not cross-cut the megasequence layering up or down in the stratigraphic section. We also examined published maps of extensive and lithologically distinct rock units, like the Morrison Formation and Pierre Shale in the Western USA. These semi- regional (multi-state units in the USA) formations were also tracked within the confines of the megasequence boundaries to test the validity of the correlations. RESULTS 1. Lithologic patterns in the megasequences A. Three-dimensional lithology models We created 3-D lithology models for each of the three continents (Figs. 5, 6, 7). The RockWorks 17 program allowed a constrained interpolation between the detailed columns and filled in the lithologic information from the closest column data. For each continent, we constructed a 3-D model that we can rotate using the RockWorks software and view from any angle. We chose to include snapshots of each of the continents viewed from two different, but consistent angles, first viewed from 225 degrees, looking northeast and from 135 degrees, looking northwest, both viewed downward at 30 degrees from horizontal. These large-scale lithologic models demonstrate the overall consistent correlation of many of the rock types across significant distances on every continent. However, as these are so large, it becomes difficult to illustrate the internal correlations from column to column. For that we constructed additional maps and cross-sections as discussed below. B. Basal lithology maps Stratigraphic depositional patterns were examined by creating basal lithology maps for all six megasequences across the continents of North America, Africa and South America (Figs. 8, 9, 10). Some of the most prominent patterns we observed within each megasequence are discussed below. The Sauk megasequence extends from the Lower Cambrian system to the Lower Ordovician system (Fig. 2). The basal Sauk lithology across NorthAmerica consists of the Tapeats equivalent sandstones (Fig. 8a). This megasequence has the most extensive sandstone layer at its base compared to all subsequent megasequences across NorthAmerica. However, much of this sandstone layer is very thin, often less than 100 m. This is especially true along the NE-SW- trending Transcontinental Arch that runs from Minnesota to New Mexico. Here, the Sauk megasequence thins to just a few 10s of meters in many places or is non-existent altogether. The thickest deposits of the basal sandstone of the Sauk megasequence are found in northernmost Canada and isolated locations along the East Coast and some of the Western states and Alberta, with thicknesses exceeding 3 km. The continuity of the basal Sauk sandstone layer across the North American continent is a testimony to the extent and uniformity of the first marine transgression of the Phanerozoic. In many places, the base of this layer is also known as the Great Unconformity. It has been mapped across multiple continents, including the other two in this study (Peters and Gaines 2012). Many creationists recognize this layer as the first extensive deposit of the Flood across major segments of the continents, with some local exceptions (Snelling 2009). This same basal Sauk sandstone layer also extends across North Africa and the Middle East (Fig. 9a). A similar pattern is observed across SouthAmerica where the Sauk is only found within portions of Peru, Bolivia and northern Argentina (Fig. 10a). The basal Sauk in South America is also composed of less sandstone and more shale compared to the other continents. These maps verify the extent of the basal Sauk sandstone layers (Tapeats equivalent) and their correlation and existence across multiple continents. The demonstrable correlation of the basal Sauk sandstone beds across vast areas of three continents illustrates the common starting point for a global geologic column. In many locations, the basal Saukmegasequence is also coincident with the Great Unconformity, and in some locations the so-called Cambrian Explosion, where marine fossils representing all animal phyla suddenly appear in the rock record. The Tippecanoe sequence extends from the Middle Ordovician system to the top of the Silurian system (Fig. 2). It has a fairly extensive basal sandstone layer that can be traced from column to column across the Midcontinent region of the USA (St. Peter Sandstone and equivalent), including an incursion into Hudson Bay. This sandstone layer is also quite thin, often less than 100 m. Some earlier maps published by creation scientists show the St. Peter Sandstone to be much more extensive than the actual Clarey and Werner ◀ A Flood origin for the geological column ▶ 2018 ICC 331