THE VALPAKAISO MOEAINIC SYSTEM. 343 



produced' by the two, and we find north of Pawpaw, the last extreme, a 

 place where neither glacier produced a definite ridge at the point where the 

 two lobes came in contact. 



RANGE IN ALTITUDE. 



The inner border of the Valparaiso morainic system, so far as examined, 

 presents but little range in altitude, being usually between 650 and 690 feet 

 above tide, or 70 to 110 feet above the level of Lake Michigan. From the 

 inner border there is usually a rise of at least 100 feet, and in places of 200 

 feet or more, to the main crest of the morainic system. This crest in the 

 Illinois portion ranges from about 750 feet up to nearly 900 feet above tide, 

 being highest in the vicinity of Lake Zurich, in southern Lake County, and 

 lowest on the borders of the Des Plaines River, in Will County. In the 

 Indiana portion the crest ranges from about 750 feet in Lake County to 

 nearly 900 feet in Laporte County. In the Michigan portion the crest is 

 750 to 800 feet in the vicinity of the St. Joseph River and northward nearly 

 to the line of Allegan and Van Buren counties. But in Allegan County it 

 presents more range, the highest points being fully 900 feet, while the low 

 points near the Kalamazoo River rise but little above 700 feet. 



On the outer border of the morainic system the altitude is generally 

 much higher than on the inner border, though in Kankakee and southern 

 Will counties, Illinois, the difference in the elevation of the inner and outer 

 borders is only a few feet. The difference is also slight in Lake and west- 

 ern Porter counties, Indiana. In the vicinity of the Wisconsin line and 

 southward as far as Elgin, Illinois, the outer border stands between 750 

 and 775 feet. It declines to about 700 feet at Naperville, Illinois, and 

 to about 650 feet in southwestern Will County, Illinois It rises thence 

 gradually eastward up the Kankakee Valley, reaching 700 feet in eastern 

 Porter County, Indiana. There is then a more rapid rise and an altitude 

 of about 800 feet is attained in the vicinity of Laporte, Indiana. This 

 altitude is maintained eastward from Laporte to the border of St. Joseph 

 County, Indiana. A descent there begins toward the St. Joseph River 

 and the altitude decreases to about 710 feet on the borders of that stream 

 north of Niles, Michigan. In passing northward, up the Dowagiac Valley, 

 the altitude along the outer border of this morainic system increases to 

 about 800 feet in Keeler and Hamilton townships, Van Buren County, 

 Michigan. It declines again to about 700 feet at the Pawpaw marsh in 



