Wisconsin Kettle Moraine. 209 



but who should not be held responsible for the special collocation 

 presented in the accompanying diagram, which, in some of its 

 details, may prudently be held as somewhat tentative, until more 

 rigorously verified. But the grand features of these movements, 

 which may be confidently accepted, are very striking, and are 

 ver}'' singularly related to the great basins of the lake region. 

 The three main channels were the troughs of the great lakes, 

 Superior, Michigan, and the couplet, Erie and Ontario, while be- 

 tween these lay three subordinate ones in the basins of the great 

 bays, Saginaw, Green and Keweenaw. 



The divergence of the striations from the main channels toward 

 the range, in the case of the Green Bay valley, and, so far as the 

 evidence goes, in other troughs, was an unexpected result, developed 

 by combining individual observations ; but, when the method of 

 wasting and disappearance of a glacier is studiously considered, 

 appears not only intelligible, but a necessary result, and one which 

 finds partial illustration among existing glaciers. 



Topographical Relations and Distribution. — The topographical 

 relations of the formation are an essential consideration, but may 

 be best apprehended in connection with its geographical exten- 

 sion, which now claims our attention. If we start with the north- 

 ern extremity of the long known Potash Kettle Eange, in Wis- 

 consin, we find ourselves about midway between the southern 

 extremity of Green Bay and Lake Michigan, and on an eastward 

 sloping, rocky incline. The base of the range is here less than 

 200 feet above Lake Michigan, and is flanked on either side by 

 the lacustrine red clays of the region : and seems, in some measure, 

 to be obscured by them. From this point, it stretches away in a 

 general south-southwestward direction, for about 135 miles, as- 

 cending gradually, and obliquely, the rocky slope, until it rests 

 directly on its crest. 



When within about twenty miles of the Illinois line, it divides^ 

 one portion passing southward into that state, and the other, 

 which we will follow, curves to the westward, and crosses theEock 

 river valley. A profile of the rock surface across this valley, 

 beneath the range, would show a downward curve of more than 

 300 feet. The range should not, perhaps, be regarded as sagging 

 14 



