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The products of the Illinois glacial lobe constitute a natural mono- 
graphic theme, for the differentiation of the border tract of the ice by 
the topographic influences of the trough of Lake Michigan gave the 
lobe a quite distinct individuality. In the monograph, however, for 
convenience the field is rather arbitrarily limited on the north where 
the products of the Illinois lobe become complicated on the east side 
with those of the Huron-Erie and the Saginaw lobes and on the west 
side with those of the Green Bay lobe. This limitation, however, 
does not seriously affect the unity of the theme. This lobe was given 
precedence because its field embraces the most southerly reach of the 
great ice mantle and because its products are unusually well deployed. 
The author’s abstract of the monograph which follows, sets forth its 
contents better than could be done by another. 
Chapter I. Introduction.— The Illinois glacial lobe formed the south- 
western part of the great ice field that extended from the high lands east and 
south of Hudson Bay southwestward over the basins of the Great Lakes and 
the north-central states as far as the Mississippi valley. It overlapped a 
previously glaciated region on the southwest, whose drift was derived from an 
ice field that moved southward from the central portion of the Dominion of 
Canada as far as the vicinity of the Missouri River. This southwestern part 
of the eastern ice field, being mainly within the limits of the State of Illinois, 
has received the name Illinois Glacial Lobe. 
The results of earlier studies by Chamberlin, Salisbury, and others are 
noted, and the plan of investigation is set-forth. A brief explanation of the 
method of numbering townships 1s presented. 
Chapter IIT. Physical features The variations in altitude are set forth 
in a topographic map and also in tables, and the marked increase in altitude 
of certain parts of the region because of drift accumulations is considered. 
The conspicuous reliefs of the rock surface are briefly touched upon, and the 
preglacial valleys receive passing notice. Profiles and maps are extended 
across the bed of Lake Michigan as well as border districts, and the inequali- 
ties of the lake basin are briefly discussed. 
Chapter IIT. Outline of time relations or glacial succession.—A sketch 
of the major and minor divisions of the drift sheets and of the intervals 
between them is accompanied by a brief explanation of the basis for the 
classification adopted. 
Chapter IV. The Illinoian drift sheet and its relations.— The Illinoian 
is the most extensive drift sheet formed by the Illinois glacial lobe and 
receives its name because of its wide exposure in the State of Illinois. The 
evidence that the Illinoian drift sheet should be separated from the outlying 
and underlying drift is briefly set forth. The aspects of the Illinoian drift 
