By Carl R. Froede, Jr. and Michael J. Oard
Working from multiple hypotheses allows creation scientists to formulate many different ideas in defining the pre-Flood/Flood boundary at the Grand Canyon. Traditional stratigraphic analysis has focused on the paleontological content of the various strata (e.g., Austin, 1994; Hoesch, 2007). However, this approach has largely been abandoned and emphasis has shifted to five discontinuity criteria (Austin and Wise, 1994; Wise and Snelling, 2005). Our own analysis of the sedimentary/metasedimentary strata in the Grand Canyon identified the pre-Flood/Flood boundary deep in the canyon at the Greatest Unconformity (Froede and Oard, 2007).
Hunter (2008) proposed that the pre-Flood/Flood boundary should be located at the 660 km discontinuity in the mantle. Barnhart (2008) has raised a similar proposal. We have serious concerns with defining the boundary down in the mantle (see Froede and Oard, 2008). While we acknowledge that there is no official definition of the pre-Flood/Flood boundary, we do not believe that it should be defined in the mantle or possibly even lower at the core/mantle boundary. This would then be an arbitrary boundary defined by a change in seismic velocity. This boundary would not serve any purpose in defining any/all overlying geological materials, be they igneous, metamorphic, or sedimentary. Perhaps diluvial seismologists, like Hunter, can define specific seismic parameters for the pre-Flood/Flood contact deep within the Earth, but this boundary is irrelevant for the sedimentary rock record found across Earth’s continental crust….