INNER BORDER OF THE GRAND RIVER LOBE. 473 



outer of these series sustains a position with reference to the glacial 

 boundary analogous to that of the outer moraine of the Grand River lobe. 

 The inner follows nearly the continental divide to the meridian of Mansfield, 

 west of which its members become more widely separated and constitute 

 the series that encircle the Maumee or western Erie Basin. It is thought 

 that the outer of these morainic series is the correlative of the main portion 

 of the outer morainic system of the Grand River lobe, while the series 

 along the continental divide may be con-elated with the fragmentary belts 

 between the outer system and the Cleveland moraine and with the swell- 

 and-sag tracts along the inner border of the outer system. 



The result of detailed investigation has been to confirm in a remarkable 

 degree the tentative correlation presented by Chamberlin in his paper on 

 the Terminal moraine of the second Glacial epoch. ^ The evidence, so far 

 as collected, sustains that correlation from Wisconsin to New York, though 

 the fi'agmentary character of the moraines in western Indiana, and eastern 

 Illinois renders a full demonstration difficult. 



In the less complicated districts of Ohio and eastern Indiana, where 

 correlation with this system may be made with certainty by means of con- 

 tinuous tracing, it is found that moraines of different age from this system, 

 both earlier and later, have contours strikingly different from it, none of 

 them presenting, except locally, so sharply ridged or indented a surface. 

 The Kettle moraine of Wisconsin is of the same type as the morainic 

 system under discussion, and on that account, and in the absence of 

 evidence to the contrary, is presumably to be correlated with it. 



It is generally' supposed that the outer moraine, mapped by Lewis, 

 from the reentrant angle near Salamanca, New York, to the Delaware ^ is 

 the correlative of the outer moraine of the Grand River lobe, but this cor- 

 relation is not fully established. The writer's studies brought out no 

 decisive evidence of difference in age. They were, however, carried but a 

 short distance east from the reentrant angle. 



That this outer moraine is very much younger than the high-level 

 terraces of early glacial age, which occur in the valleys leading south from 

 the glacial boundary in western Pennsylvania, seems beyond question, 

 since, as already shown, the moraine-headed terraces which start from this 



1 Third Annual Report U. S. Geol. Survey, 1881-82. 



^ Described in Second Geol. Survey Pennsylvania, Report Z. 



