1. Transcontinental geophysical survey (35°-39°N) bouguer gravity map from 100° to 112° W longitude / [cartographic material] Yale Public content 1968. 2012-10-10T15:25:23Z. 2013-03-18T22:22:43Z. Dept. of the Interior, U.S. Geological Survey. English. Public. Great Plains and West (U.S.).