A regional gravity survey in the eastern Snake River Plain was conducted in the early summer of 1961. Seven hundred and seven gravity stations were established between latitudes 42?15N and 4415N and 44?30N between longitudes 111?30W and 114?30W. Three hundred and twenty-five of these stations were located in 2,700 square miles of the eastern part with an average density of one station per 8.3 square miles. The remaining 9,300 square miles were covered by several lines, with an average lineal density of one station per 2.0 miles. A simple-Bouguer gravity contour map has been made of the area by standard methods. The low gravity relief and broad high of the eastern Snake River Plain strongly contrasts with the high amplitude anomalies of the western plain. The major anomalies of the eastern plain consist of 1) a broad high, which is an extension of the large gravity highs of the western plain,...