190 Wisconsin Academy of Sciences^ Arts and Letters. 



beach lies 1,400 — 2,100 feet from the lake shore, and the maximum depth 

 of sand (25 feet), is about 1,700 feet from the lake. On the west border 

 from 2,100—2,600 feet, the depth is about 17 feet, and from 2,600—6,000 feet 

 it averages about 12 feet in depth. From the latter point westward the 

 depth gradually decreases and the sand disappears 1,900 feet east from the 

 Chicago river. From the inner border of the beach ridge, to the lake shore 

 a distance of 1,400 feet, the deposits are about 18 feet in depth. At the 

 water's edge the depth is but 10 feet. The profile continues out 1,100 feet 

 beneath the lake and there is but three feet of sand and gravel at its termi- 

 nus. The deposit throughout is mainly sand, but some gravel was en- 

 countered. Shells of Unios and other mollusks were imbedded at frequent 

 intervals throughout nearly the whole width of the deposit. Beneath these 

 beach deposits there is everywhere a pebbly blue-gray clay, and no difference 

 could be detected in emerged and submerged portions. This pebbly clay is 

 described in a previous chapter. 



In Hyde Park, the lower beach contains much more gravel than is shown 

 in the Fullerton Avenue profile. The width of the system of raised beaches 

 between Hyde Park and Englewood, is fully one mile, and between these 

 beaches and the present beach, the surface is covered with sand and gravel. 



At Eiverdale the beach deposits are scarcely four feet in depth, but at 

 Dolton Junction they are eight feet and two miles east qf Dolton, the 

 depth, along the west of the ridge is 12 — 15 feet, and at the state line it is 

 reported to be about 24 feet. The \^'hole surface from Lake Calumet south 

 to the beach ridge just alluded to. is covered with sand, the depth of which 

 in places is at least 18 feet. The whole interval in fact between the lower 

 raised beach and the present lake shore is covered with sand, not only in 

 Illinois, but also in Indiana and Michigan, as will appear on a subsequent 

 page. Its separation from the present beach is merely a matter of eleva- 

 tion, apparently, consequent upon the gradual lowering of the level of the 

 lake. 



The beach which enters Indiana about 1^ miles south of Hammond, passes 

 east through the villages of Hessville, Tolbston and Miller, lying 1 — 2 miles 

 north of the Little Calumet, and about an equal distance south of the 

 Grand Calumet river . East from Miller the beach is quite continuous as 

 far as Michigan City, lying 1 — 2t} miles back from the present beach. 

 East from Michigan City there are only fragmentary beach lines, the dis- 

 tribution of which will be given presently. 



Between the beach just described and the present beach, there are in 

 Lake County, Indiana, a series of lower beach lines separated by narrow 

 swamps, which fill the whole interval between the lake and the beach, 

 leaving no such broad level tracts as occur between the Middle and Lower 

 beaches along the Little Calumet and between the Upper and Middle 

 beaches along Caeby marsh. On the meridian of Hessville, there are not 

 fewer than thirty of these lower beach fines . These beaches are more 

 closely associated with the main Lower beach in Porter county, for the 



