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The Early Wisconsin Terminal Moraine 



The region of the early Wisconsin terminal moraine separates the 

 northern prairies of Illinois from the more broken rolling upland to 

 the south, and forms part of the boundary between the northern and 

 southern Illinois regions, as described in this report. From its top, 

 the view to the north shows a level prairie, while to the south there 

 stretches a rolling country cut by the stream valleys which flow south 

 and southeast to the Wabash River or south and west to the Kas- 

 kaskia. The moraine may be located roughly as a belt which starts 

 in the east near Paris and sweeps around in a curve through Kansas, 

 south of Charleston, Mattoon, and Windsor, and turns north through 

 Macon and near Decatur. 



The chief streams that cut through this country are the headwaters 

 of the Embarras in the central part and the Okaw in the northwest. 

 The main streams flow through rather deep, narrow, steep-sided valleys 

 with some rock outcrops near the bottoms. These deep valleys are 

 confined, however, to the transition country where it changes from the 

 level prairies at the north to the lower level land at the south, while 

 farther back towards the upper waters of the small streams the valleys 

 are broad and shallow. 



The moraine shows no very distinct line of demarkation from the 

 prairie to the north, but embayments of the latter mark a rather 

 indefinite, irregular boundary. To the south there is again more 

 prairie land at a lower level, with the descent between the two altitudes 

 broken up by the relatively deep valleys which the streams are 

 compelled to cut to adjust their grades. 



Studies of the forests were made near Paris, Kansas, Charleston, 

 Mattoon, and Windsor, and are chiefly of interest in showing the 

 mixture typical of the edge of the prairie and of the stream valleys 

 which cut into the prairie. 



The forests of the level country to the north and south of the 

 morainal belt are of similar composition, and are in small woodlots 

 which dot the prairie edge here and there. They are of a type which 

 is rather unique and confined to the level land, being the advance 

 growth of the forest as it encroaches on the prairies. 



These woodlands are often referred to as "oak openings," and 

 are differentiated by the occurrence of shingle oak. Sometimes it is 

 found in pure stands, but more often in mixture with elm, honey 

 locust, white and black oaks, hickory, and ash ; more rarely with pin 

 oak or hackberry. 



The forests of the rougher morainal country along the stream 

 valleys, and sometimes extending back to some extent on the more 

 rolling portion of the uplands, are of types that are characteristic of 



