liaised Beaches of Lake Michigan. 181 



South of the sag a sea cUff was formed along the foot of the Valparaiso 

 moraine for about 15 miles southeast from the Des Plaines valley, the 

 sag itself lying near the foot of the moraine for 10 miles or more. The 

 Wabash railroad rises onto the moraine from the sag, whose elevation, as 

 shown by its profile, is but 16 feet above Lake Jlichigan. The gravel 

 flanking the high land each side of the sag indicates that a depth of 40 — 50 

 feet of water passed througu it at the time of the formation of the upper 

 beach lines. 



The plain in Tp. 36 N. , R. XIII E. , which lies between the sag and the 

 moraine, rises toward the moraine quite rapidly, its border next the mo- 

 raine being 50 feet above Lake Michigan at the point where the C. , R. I. 

 and P. Ry. passes from the plain to the moi'aine. The sea cliff here rises 

 28 feet above the plain or 78 feet above Lake Michigan. It is not probable, 

 however, that the water stood as high as the top of the cliff. There is 

 evidence along the border of the moraine, a short distance east, that it was 

 some five feet or more in depth — for sand and gravel deposits flank the' 

 moraine to about this elevation above the level of the plain. 



In the northwest part of Sec. 35, Tp. 36 N., R. XIII E., a beach line 

 leaves the border of the moraine, and from this point southeast to the state 

 line near Dyer, Indiana, it lies one to two miles north. The Illinois Cen- 

 tral raih-oad crosses it about one mile north of Home wood. The top of the 

 ridge is 65 feet above Lake Michigan (as shown in the profile of this rail- 

 road). The beach deposits cover a width of nearly a mile where crossed by 

 this railroad, and their north border is but 41 feet above Lake Michigan. 

 The liighest portion of the ridge is mainly sand, and evidently was drifted 

 by the wind so that its crest is now several feet above the water level at 

 the time of the formation of the beach. 



At the crossing of the Chicago and Eastern Illinois Railroad near Glen- 

 wood, the crest of the ridge is 55 feet above Lake Michigan. The ridge 

 maintains about the same elevation to Dyer, Indiana. A sea cliff flanked 

 by beach gravels is developed near the state line. 



Before taking up the description of this beach in Indiana we will note 

 the effect produced by the lake upon " Blue island," a till ridge running 

 north from Blue Island village, some five or six miles. It is evident that 

 this till ridge was an island in the old lake, for its boi'der is very abrupt like 

 a sea cliff and its surface is billowy. Furthermore flanking nearly the 

 whole of the western face — there are beach deposits — whose base is 35 — 

 45 feet above I^ake Michigan. Toward the north end of the ridge the sand 

 has drifted into dunes, a few of which attain an elevation of 80 feet above 

 Lake Michigan, but the beach gravels were nowhere observed to have an 

 elevation to exceed 55 feet above the lake. From the north end of the 

 ridge a bar composed of both sand and gravel extends out across the plain 

 iu a W. S. W. du-ection for more than a mile. The plain is about 45 feet 

 above Lake Michigan, and the bar rises in plains to an elevation of 15 feet 

 above tliis plain. This was evidently formed in the lee of the ridge and is 



