68 CHICAGO ACADEMY OF SCIENCES. 



Its faintness in this district is probably due, in part, at least, to the 

 protection from wave action occasioned by the bar just described. 

 Upon passing south and crossing- Salt Creek, about a mile from 

 the point where the beach fades out, it reappears as a well-defined 

 ridge, composed of sand and gravel, rising from lo to 12 feet above 

 the border of the plain on the east, and having a breadth of 30 to 40 

 rods. Following this beach southward, it changes in 

 about a mile to a cut terrace, which is well defined from that point 

 southward to the lake outlet, a short distance south of LaGrange. 

 Its course is through the eastern part of the city of LaGrange, 

 where it is in the form of a cut terrace, with bank 10 to 15 feet in 

 height. 



Passing to the west side of the outlet, near Willow Springs, 

 the shore line is found as a cut terrace along the east face of the 

 prominent morainic tract which occupies the interval between the 

 two outlets of the lake. Though mainly a cut terrace the moraine 

 is flanked occasionally by deposits of gravel and sand. 



South from the southern, or Sag, outlet the shore is carved on 

 the inner face of the Valparaiso moraine with banks 5 to 20 feet, or 

 more, in height, but with only occasional deposits of gravel and 

 sand. Upon approaching the State line, however, near Glenwood, 

 the shore bears away from the moraine and deposits of gravel and 

 sand are built up to a height of 6 to 12 feet or more. These are 

 sometimes in the form of a single ridge, but not infrequently a 

 series of parallel ridges occur, separated by narrow sags. 



The effect of the waves at this lake stage is discernible on 

 the borders of Blue Island till ridge, though the western border is 

 characterized by dunes which conceal to some extent the action of 

 the lake. 



Upon passing into Indiana the beach soon becomes sandy, 

 like the shore of the present lake, and dunes with an elevation of 

 10 to ^5 feet are formed throughout much of the course in that 

 State. These dunes, in places, have drifted out for a mile or more 

 beyond the old lake border, reaching elevations somewhat higher 

 than the level of the lake. There are occasional points where 

 gravelly deposits have been found in connection with this shore 

 in Indiana and also in Michigan, but the sand, as a rule, conceals 

 the shore products of the lake. One of the best instances noted of 

 a gravelly beach formed at this stage is at Sawyer, Michigan, a 

 few miles south of St. Joseph. The beach is well exposed by a 

 wagon road leading west from the village, about 100 to 120 rods 



