THE PLEISTOCENE OF INDIANA AND MICHIGAN AND THE 

 HISTORY OF THE GREAT LAKES. 



By Frank Leverett and Frank B. Taylor. 



CHAPTER I. 



INTRODUCTION. 



By Frank Leverett. 



OUTLINE OF AREA AND SUBJECTS OF DISCUSSION. 



The area discussed in this monograph lies between that discussed in Monograph XXXVIII 

 (The Illinois glacial lobe) and that hi Monograph XLI (The glacial formations and drainage 

 features of the Erie and Ohio basins). It includes a considerable part of Indiana and all of the 

 southern peninsula of Michigan. The monographs referred to contain a discussion of the entire 

 exposed portion of the Ilhnoian drift in Indiana as well as in the neighboring States on the east 

 and the west. The question of a pre-Illhioian drift in southern Indiana arose subsequently 

 through studies -in 1902 and is briefly treated in the present paper, but the Wisconsin drift, 

 the concealed portions of the earlier drift sheets that underlie it, and the somewhat intricate 

 lake history associated with and following the retreat of the ice are the main subjects of dis- 

 cussion. 



FIELD WORK. 



The Wisconsin and underlying drifts have been investigated chiefly by Mr. Leverett, and 

 the lake history has been worked out largely by Mr. Taylor. During the investigations in 

 Michigan, however, field conferences were frequent, so that each author is in a measure familiar 

 with the main features and problems discussed by the other. Mr. Taylor's work in the neigh- 

 boring portion of Canada, some results of which are presented, was carried on largely at private 

 expense prior to his connection with this Survey. It was continued under the auspices of the 

 Canadian Survey in 1908, 1909, 1911, and 1912. 



The work of Mr. Leverett in Indiana and Michigan and that of Mr. Taylor in Michigan 

 has been prosecuted chiefly under the direction of Prof. T. C. Chamberlin, who by his active 

 interest, helpful suggestions, and occasional field visits has greatly stimulated the work and 

 aided in the interpretation. 



Dr. A. C. Lane, as State geologist, cooperated in the work in Michigan by helpful sugges- 

 tions and contribution of valuable data which had come into his possession. He also, through 

 an arrangement with the United States Geological Survey, contributed to the work from the 

 State funds on the understanding that the State Survey should receive special reports on areas 

 investigated by the aid of such funds. Through this arrangement Lapeer County was studied 

 and described by Mr. Taylor in 1900, and Alcona County by Mr. Leverett in 1901. In addition 

 to this the members of the State Survey have studied in some detail the Pleistocene features 

 of Arenac, Bay, Huron, Iosco, Kent, Monroe, Saginaw, Sanilac, Tuscola, and Wayne counties 

 with results that appear hi the State reports. The work in these counties was so thorough that 

 only a review was needed to connect it fully with the work in the bordering counties. 



The annual reports of the Indiana Geological Survey contain results of somewhat detailed 

 studies of the glacial deposits of certain counties and general observations on the drift of the 



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