When a one-half ounce spherical charge of high explosive is detonated over a flat plane bounded by a 5 degree incline, the type of phenomenon encountered depends on the distance from ground zero to a beginning of the incline. If this distance is 48" the wave assumes a smooth contour on the plane. Detailed investigation of the shock velocity above the plane reveals that there is a pressure gradient along the shock front for a considerable region which replaces the usual triple point.