A program to map geologic structure and/or stratigraphic features employing the seismic-reflection method. Measurements are made of the arrival time of events attributed to seismic waves that have been reflected from interfaces where changes in acoustic impedance occur. Usually the objective is to map the depth, dip, and strike of the bedding, and lateral changes in the reflectors. A second objective is to define stratigraphic variations. Conclusions are usually on changes in normal-moveout, amplitude, and/or waveshape of reflection events.