This paper is a summary of the results of a study, not yet completed, of the Tertiary and Pleistocene gravel terraces and associated glacial deposits and erosional phenomena of the plains of Montana, Big Horn Basin, Wyoming, and adjacent areas. The writer’s studies, which have extended over a large part of six field seasons, are in the nature of a rapid reconnaissance of this vast area for the purpose of adding to and correlating data observed by a large number of other geologists who have worked in this region. The deposits mapped and the correlations made are shown on plate 11 as well as can be done on this small scale. It is hoped to present a better map, more detailed descriptions, and discussion of the evidence in an official paper now in preparation. Most of the detailed mapping, where such has been done, is the work . . .