THE GLACIAL LAKE CHICAGO. 443 



Michigan, and the strong beach which occurs at 60 to 65 feet above the 

 lake. Tracing somewhat in detail, its course is as follows: 



From the Wisconsin line southward to Chicago River, just above the 

 city of Chicago, it is closely associated with the upper beach, so that where 

 one beach is cut away by the lake the other is also. The Second beach 

 flanks the inner border of the upper beach in Niles Township. From the 

 Chicago River to the Des Plaines the Second beach is separated from the 

 upper beach by an interval of 1^ to 3 miles and passes somewhat directly 

 from Jefferson Park through Austin to Riverside. The head of the outlet 

 of Lake Chicago at this stage was at a line connecting the villages of River- 

 side and Summit. The beach gravels are well developed for a short distance 

 below Summit on the east side of the outlet, while the west side is marked 

 by a cut bank of corresponding elevation. The beach proper leads some- 

 what directly southeastward from Summit to the north end of Blue Island 

 Ridge and then southward along the east side of the ridge, past Washington 

 Heights, coming to the Calumet River 2 or 3 miles east of Blue Island. 

 The Sag outlet had its head at this time in a wide opening between the 

 Calumet River and Thornton. Immediately east of Thornton the beach 

 appears in its customary strength and passes thence eastward into Indiana. 



Upon entering- Indiana the beach follows the south border of Calumet 

 River across Lake County and western Porter County to the point where 

 the upper beach, as noted above, passes to the north side of the river. It 

 is closely associated with the upper beach from near the village of Ross, 

 Indiana, eastward. It is also closely associated with it for several miles 

 east from the point where it crosses the Calumet River, but in the vicinity 

 of Furness the two beaches become separated by a nearly level swampy 

 tract, about one-half mile in width, and continue distinct to Trail Creek, 

 just east of Michigan City. The Second beach passes through the south 

 part of that city. 



Upon passing into Michigan, this beach becomes so greatly obscured 

 by the belt of dunes formed along the border of the lake that exposures are 

 found only at a few points. In several places in Berrien and Van Buren 

 counties it was recognized and found to have an altitude 35 or 40 feet 

 above Lake Michigan. The exposures in every case are along the bluff of 

 the lake. As already indicated, the writer has had opportunity to make 

 only a hurried reconnaissance of the lake border northward from Van Buren 



