THE LAKE-BORDER MORAINIC SYSTEM. 393 



At South Haven, Michigan, a well at the basket factory entered rock 

 at 105 feet below lake level. A well on the farm of J. Irving Pearce, a few 

 miles southeast of South Haven (in sec. 31, T. 1 S., R. 1G W.), entered rock 

 at 130 feet below lake level. A well on the farm of W. F. Conner, in 

 sec. 34, T. 2 S., R. 17 W., reached a depth of 220 feet and a level 125 feet 

 below Lake Michigan without entering rock. 



A well in the southeast part of T. 1 N., R, 17 W., 157 feet in depth, 

 reached a level nearly 100 feet below Lake Michigan without entering rock 

 Another well in sec 29, T. 1 N„ R. 16 W, 140 feet in depth, reached a 

 level fully 100 feet below the lake without entering rock. 



At D. Kitchen's, in sec 16, T. 2 K, R. 16 W., a well reached a depth 

 of 275 feet and a level 165 feet below Lake Michigan without entering rock. 



A well 1J miles southeast of Pier Cove, Michigan, 142 feet in depth, 

 reached a level about 75 feet below the lake without entering rock. 



STRUCTURE OF THE DRIFT. 



At many points on each of these ridges there is a thin coating of sand. 

 It is usually drifted into low knolls and ridges, and was apparently deposited 

 in large part by wind. Where these sand deposits are 8 or 10 feet in depth 

 wells along the ridges often pass into a blue till at the base of the sand, but 

 where the sand deposits are thin or absent a yellow till several feet in depth 

 occurs at the top of the blue till. In several sections, as shown below, the 

 yellow till was found to have a thickness of but 3 or 4 feet. The usual 

 thickness, however, is nearly twice that amount, and in places is not less 

 than 20 feet. The ridge on the north side of the Calumet River, in Porter 

 County, Indiana, furnishes several well sections in which the thickness of 

 the yellow till is 15 or 20 feet. The body of the ridges seems to be com- 

 posed of blue till having a large clayey constituent, and on the whole more 

 compact than the blue till found in the Valparaiso morainic system. The 

 till also is less stony as a rule than typical till. This till is occasionally 

 replaced by sand or gravel, and it generally contains pockets and thin beds 

 of sand and gravel of sufficient extent and at convenient depths to supply 

 the shallow wells. There are places where a nearly pebbleless laminated 

 clay replaces the till. 



Bowlders are found in moderate number along each of the rido-es. 

 They consist largely of granite rocks, though there are many other classes 

 of rocks present. As is usual in the moraines of this region, the surface 



