Wisconsin Keith Moraine. 215 



-esting way in which it is associated with the latter formation, and 

 the suggestions it may contribute to the final solution of the main 

 problem, to which the special one under discussion is only a trib- 

 'Utary, viz. : the definite history of the Qaatenary formations. 



Eeturning to the branching of the range in southeastern Wis- 

 consin, we find the left arm, or that nearest Lake Michigan, strik- 

 ing southward into Illinois. If we lay before us Prof. Worthen's 

 ■geological map of that state, and attentively observe its topo- 

 graphical features and its drainage systems, it will be observed 

 that nearly all the lakelets, the greater part of the marshes, and 

 most of the region of abnormal drainage may be included in a 

 ■curving line, rudely concentric with the shore of Lake Michigan, 

 starting near the center of McHenry county, on the] Wiscon- 

 sin line, and ending in Yermiilion county, on the Indiana border. 

 It may also be observed, on a similar inspection of Indiana, that 

 nearly all the lake district lies north of the Wabash. 



In Wisconsin, as already stated, we have found this area bor- 

 dered by the Kettle range, which is itself notably lake-bearing. 

 The range continues to sustain this relationship in Illinois, so far 

 as I know it to be directly continuous. It exhibits a progressive 

 broadening, and flattening, as it enters upon the level country 

 that encompasses the head of Lake Michigan. The pebble clay 

 deposit — not coarse boulder clay — that characterizes the flat 

 couatry, and which, to the north, has been separated from the 

 range by a belt of coarse boulder clay, here approaches, and ap- 

 pears, to some extent, to overlap the range, and to be one cause of 

 its less conspicuous character. From what I have seen of the 

 ■region south of Lake Michigan, and from all I can find in geologi- 

 cal reports relating to the region, I gather that the range, so far 

 as it escaped the destructive action of the floods issuing from the 

 Lake Michigan basin, both while occupied by ice, and subse- 

 quently, is, to a large extent, buried beneath later deposits, or so 

 modified as to be inconspicuous. Whatever the correct interpre- 

 tation, it remains a fact beyond question, that the belt becomes 

 very obscure, compared with its development to the northward. 

 Dr. E. Andrews says: "As we trace it southward, the material 

 ^becomes finer, and the hills lower, until they shade off impercepti- 



