190 



discharges at South Chicago in Illinois. The old discharge was in Lake 

 County on the southeast border of the lake. Near the source the river 

 flows in an almost straight line and has the appearance of an artificial 

 ditch rather than a natural stream. After flowing across the counties 

 of Porter and Lake it crosses the State line but three miles south of 

 its entry into Porter County and almost due west of its source. From 

 the State line it flows in a northwesterly direction, for about seven miles 

 and then at Blue Island, Illinois, it makes a sharp curve, then flows north- 

 east then southeast and again crosses into Lake County about three miles 

 north of its first line then continuing eastward for fourteen miles to 

 its old point of discharge, but two and a half miles from the ix)int where 

 it first entered Lake County. The area included in this meander con- 

 sists of slightly elevated niorainic tracts, sandy beaches and marshes. 



LAKES. 



In the northern part of the State are hundreds of lakes varying much 

 in size. These lakes are chiefly confined to the four northern tiers of 

 counties. These lakes are all due to the irregular deposition of glacia! 

 drift. They occupy basins within the niorainic area. They may be di- 

 vided into three classes. (1) Kettle Hole Lakes, those which have been 

 formed by the melting of detached bh)cks of ice. (2) Channel Lakes, in 

 which the basins are the abandoned clianncls of glacial streams. (3) 

 Irregular lakes, those with no general form of outline but are due to the 

 irregular depressions formed in the accumulated drift. 



The al)undant vegetation has produced considerable deposits of peat 

 al)out the margins of many of the Inkes. and many of the smaller ones 

 have been completely filled. Good iiiari deposits also occur in many of 

 the lakes and is being utilized for (he niannfacture of cement, brick and 

 tile. 



No lakes occur outside the limits of the Wisconsin drift, although 

 many basins of e.xtinct lakes occur over the scmthwestern border of 

 the Illinoian. Some small ponded areas are found which take consid- 

 erable proportions in wet seasons but are not permanent. In the drift- 

 less area numerous small ponds are fcmnd, which owe their origin chiefly 

 to sink Iiole depressions in wliidi the ontlel has become clogge<l. 



For di'scrlplloii of In<li.in.i S(r(>ams, seo TT. S. O. S. Mdiiovriaplis XXXVII and 

 XLI.— Leverett. 



