THE BLOOMINGTON" MOEAINIC SYSTEM. 261 



North of the creek the moraine consists of a series of knolls and sharp 

 ridges standing 20 to 50 feet above bordering valleys or depressions. 



In the southeast part of T. 32, R. 4 E., the moraine swings abruptly 

 westward, passing through the village of Grand Ridge to Farm Ridge post- 

 office. It carries knolls which rise to a height of 20 feet or more. Between 

 Grand Ridge and Farm Ridge the topograph)- is of a subdued knob-and- 

 basin type. From Farm Ridge to the Illinois bluff near Utica there is a 

 smooth ridge with very gentle undulations, but with a well-defined relief 

 of 20 or 30 feet. This ridge is in places capped by sandy knolls 10 to 15 

 feet in height, apparently wind drifted. 



The portion of this moraine north of the Illinois River consists of 

 three disjointed ridges arranged end to end, but varying greatly in the 

 direction which they trend. The}- may be traced readily on the Lasalle 

 and Ottawa topographic sheets. The southern one has its southern termi- 

 nus at the north bluff of the Illinois River between Little Vermilion River 

 and Pecumsaugen Creek. It leads northward through Lasalle Township 

 for 2 miles or more, then curves slightly and turns east of north, passing 

 through sees. 30, 19, 17, 9, and 4, Waltham Township. It then drops down 

 rapidly just north of the township line. The second ridge appears within 

 a mile northeast of its terminus, and bears slightly west of north for a 

 distance of about 3 miles, when it also drops off suddenly near Tomahawk 

 Creek. North of Tomahawk Creek a third ridge appears, which bears 

 northward for about 2 miles, then bends toward the northeast and comes to 

 Big Indian Creek about 2 miles below Earlville. No well-defined continu- 

 . ation was found on the north side of this creek, though there are occasional 

 knolls along the divide between Big Indian and Little Indian creeks, in 

 both Lasalle and Dekalb counties, which may mark the line of its con- 

 tinuation, and which would connect it with the main portion of this morainic 

 system east of Shabbona. The ridges whose courses have just been out- 

 lined have, as a rule, a sharp crest as well as swells and sags. The southern 

 one is spoken of by the residents as the "Backbone," since it is quite sharp, 

 standing in places 60 to 80 feet above the border districts, and being 

 scarcely a mile in width. The ridge north of it has a height of 60 to 75 

 feet above the bordering plain, while the northernmost ridge has a height 

 of 30 to 50 feet, except near its northern terminus, where it drops down 

 to a height of but 15 or 20 feet. 



