An experimental study of the origin of salt domes was suggested by Dr. W. T. Thornm, Jr., and Mr. Max Ball at the Houston meeting of the American Association of Petroleum Geologists. The experiments described in this paper, which were performed in the Oil and Gas Laboratory of the School of Mines, University of Pittsburgh, are the outgrowth of that suggestion.' The purpose of these experiments was to show the effect of dynamic forces upon a plastic bed, interbedded with layers of varying hardness and covered by an