I in VICTOR E. SHELFORD. 



Originally, there were probably a number of outlets to the 

 ;em of ponds which were joined to one another by the-e 

 outlets and through various lo\v pl.- t - in the sand rid^e-. In 

 the area of our concentrated study then' is an outlet (Map II 

 which has served to connect all the younger por.ds in an intimate 

 fashion. 



The building of sew< -ociatcd with the growth of northern 



Indiana towns (\Vhiting, Ka-.t Chicago, Hammond and Gary) 

 has drained la rue portions of the pond-, u hile roads and railroad- 

 have isolated other portions. 



2. Origin of the Ponds. During the linal retreat of the North 

 Americ;m ice sheet, its Lake Michigan lobe stood for a time with 

 -outhern end at the cresl of the Valparaiso moraine which 

 live.- concentrically around the -oulhern end of Lake Michigan. 

 When the ice retreated from this position, water occupied the 

 ce between this lobe of the sheet and the moraine. Thiswa- 

 Lake Chicago, the forerunner of Lake Michigan. Affr having 

 stood respectively 60 feet, 40 feet and 20 feet above its present 

 level, long enough to deposit conspicuous beaches, it took up a 

 position at a 12-foot level. The waters appear to have fallen 

 dually Irom this level. At present one or two ridges and 

 depressions similar to those found above the water on old I 

 Chicago plain, are below the surface of the water along the shore 

 at the south end of Lake Michigan. The retr< a1 of the water- 

 has evidently exposed such ridges as fast as they were formed. 

 This has left a series of parallel ridges and ponds urnui^ed in tin- 

 order of their age the oldest furthest from the hike, the youngest 

 nearest the luke. ' 



These ponds are not all of the same size. The largest ones 

 were selected lor study and will be rel'-rrcd to in the paper by 

 number as the entire series is counted inland from the lake shore. 

 There are between seventy-five and ninety of these ponds or 

 depre--ion- between the lake shore and the Jo-foot beach level. 

 This is the maximum number. Map l.-h<>\\sihat as \\epass in 

 cither direction from the area "I" stud their numlur decreases. 



1 For a trr.it iin-iit Mt iiii- -ul.; cited in the bibliography i>ui nol 



specifically n-i<-n-cl tn ln-if. l'i i 1 ; < - i!i-lnn\ ti'lU im- tli:it tli' 



question conccniinu tin- n-l;iti\ m p!i\ -i'>^i.i|iliii r\ -ji 



