This paper reports our efforts to model the effects of grain size, recrystallization, creep, and texture on overall rock strength within the Earth’s mantle during the Genesis Flood. Our study uses experimental rheological data obtained from the mineralogical literature for olivine, which is an important mantle mineral. We apply an Internal State Variable (ISV) constitutive model within the framework of the TERRA finite element code to capture the subscale structures and their associated dynamics, strength, and viscosity effects during the Flood episode. Our numerical investigations, in both 2D and 3D, that include the improved deformation model reveal even more clearly that the potential for mantle instability enabled an episode of catastrophic plate tectonics to occur. This mantle instability arises from the extreme weakening behavior resulting from the relationship between microstructural features (herein texture, recrystallization, and grain size) and thermomechanical properties (e.g., stress and viscosity) under the conditions of temperature, pressure, and strain rate within the mantle during the Genesis Flood. It is our conviction that such an episode played a major role in the global Flood described in Genesis 7-8
