In January and February, 1960, Lawrence Radiation Laboratory personnel conducted a series of experiments in Phase II of Project Cowboy in which tourmaline crystal transducers, located very close (3 to 50 feet) to tamped high explosive detonations, detected dynamic elasto-plastic stress waves generated in salt. The detonations occurred 110 feet below the 800-foot working level of the Carey Salt Mine, near Winnfield, Louisiana. These experiments were designed to measure dynamic stress conditions resulting from explosion in the earth media, of which little is known at present, and to provide data for comparative calculations on seismic disturbances from tamped explosions and from explosion in large underground cavities. Eleatic stress waves of 1 kilobar magnitude were observed, with velocities of about 15,000 ft/sec. Inelastic stress waves up to 6 kilobars in magnitude were measured. Velocities for these waves were in the range 9000 to 12,000 ft/sec.