The meta-arkoses of the Thunderhead Sandstone in the Great Smoky Mountains of Tennessee and North Carolina contain both detrital zircon grains and metamorphic biotite flakes in all zones of regional metamorphism. The original sandstones after deposition would have contained water. Furthermore, the reaction responsible for the mineralogical changes at the staurolite isograd would have produced large volumes of water. Thus it was predicted that during the regional metamorphism these waters as hydrothermal fluids should have transported Po from the zircon grains to the biotite flakes to generate Po radiohalos in the latter. Also, the greater volume of hydrothermal fluids at the staurolite isograd should have generated more Po radiohalos there. Both predictions were verified, with four–five times more Po radiohalos in the meta-arkoses straddling the staurolite isograd. These results also verify the hydrothermal fluid transport model for Po radiohalo formation. It was concluded that the regional metamorphism, the hydrothermal fluid flows, the cooling of the regional metamorphic complex, and the formation of the Po radiohalos all had to have occurred within a few weeks. This is feasible in the context of catastrophic plate tectonics and grossly accelerated 238U decay during the Genesis Flood.