| Summary: | Introduction: It seems important that several general facts should be stated for the full understanding of terms used and allusions made in this report. The field considered is the region lying between the Missouri and James rivers, and between the latitudes of Jamestown, N. Dak., and Huron, S. Dak. 1. As has been stated in papers published by Chamberlin, Upham, myself, and others, several more or less distinct moraines have been observed in the Mississippi Valley. It has been found convenient to distinguish the outermost three by special names. President Chamberlin has named them, beginning with the outermost, Altamont, Gary, and Antelope moraines, from localities south of Big Stone Lake, and these names have been quite generally adopted. Upham and others have named them the First, Second, and Third, and as the outermost two are the more prominent, they have also been called the Outer and Inner moraines. Each of these, especially the First and Second, has subordinate divisions, which mark the borders of the different lobes into which the margin of the ice sheet was often divided. 2.) It is assumed that the reader is familiar with the generally recognized features of drift formations, such as the undulating topography and the series of drift deposits, covering an area with successive layers of till in a manner which might be compared to a nest of spoons of assorted sizes, the smaller lying inside the larger. Of these spoonshaped deposits, the moraines form the outer rims. 3.) As the moraines are the most conspicuous features of the drift formations, we may take them as the basis for dividing the subject. Not only are they the most conspicuous features of the topography, but they mark culminations of glacial activity. We therefore propose reviewing our subject under the following heads: I.) The First moraine and its attendant deposits. II.) The Second moraine and its deposits. III.) The Third and succeeding moraines. IV.) General notes and inferences. This seems to be the fitting place, also, in which to acknowledge several important favors received by me while I have been engaged in the work. The Chicago, Milwaukee and St. Paul Railway Company has not only furnished me much free transportation, but its chief engineer has furnished me elevations along its lines whenever requested. Similar favors have been shown me by Mr. A. Anderson, chief engineer of the Northern Pacific Railroad, and by Mr. W. W. Rich, chief engineer of the Minneapolis, St. Paul and Sault Ste. Marie Railway Company.
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