THE LAKE-BOEDER MORAINIC SYSTEM. 387 



State line. But here there is a very narrow gap and the ridge continues 

 in a southwestward course across northwestern Laporte County, Indiana. 

 The ridge is very weak for a mile or more about 5 miles southwest from 

 where it crosses the State line, and there is a narrow gap at Trail Creek. 

 From Trail Creek westward to the vicinity of Furness, in Porter County, 

 a distance of about 12 miles, the ridge is double and the members are 

 separated by a marsh a mile or less in width. From Furness westward to 

 Bailey the ridge presents but a single crest. Near Bailey a belt of promi- 

 nent dunes which border the shore of Lake Michigan spreads out to the 

 south in such a way as to make it difficult to trace the low till ridge. It 

 seems probable, however, that the till ridge continues but little beyond 

 Bailey, for no evidence of its presence could be found in railway cuttings, 

 which are quite numerous in the midst of the belt of dunes. 



A possible continuation of this ridge is found toward the south in a 

 narrow till ridge which leads southward from a point near Chrisnian to the 

 Valparaiso morainic system at Wheeler. This would involve an abrupt 

 southward turn in the ice margin and bring it to the inner border of the 

 Valparaiso morainic system. 



In Lake County, Indiana, no sharply outlined till ridge has been found, 

 but a low ridge with undulatory surface leads westward from Deep River 

 at Hobart along the north side of Turkey Creek, a distance of about 5 miles. 

 It is separated from the inner border of the Valparaiso morainic system only 

 by a narrow plain, scarcely a mile in average width. Possibly this marks 

 the continuation of the ridge under discussion. The system of ridges is as 

 obscure in western Porter and Lake counties, Indiana, as in southern Cook 

 County, Illinois. It, therefore, is no easy matter to decide upon the posi- 

 tion of the ice margin in these counties at the time the outer ridge was in 

 process of formation in counties to the east. 



This till ridge governs drainage to a marked degree. In the Indiana 

 portion South Galien River, East and West Trail creeks, and Calumet River 

 all have their courses toward Lake Michigan checked and courses parallel 

 with the lake produced by its presence. In Michigan the north flowing por- 

 tion of North Gralien River is, for several miles, parallel to the outer border 

 of the ridge. The relief of the ridge scarcely reaches 50 feet where sharp- 

 est, and is usually but 20 or 30 feet. The plain outside rises from the border 

 of the ridge toward the Valparaiso moraine, thus leaving along the outer 



