530 THE ILLINOIS GLACIAL LOBE. 



from north to south, but they are scarcely sufficient to prove a warping of 

 the valley floor. A boring in the abandoned channel west of Lafayette 

 enters rock at the remarkably low altitude of about 300 feet above tide, 

 while at Terre Haute several borings made in the middle part of the valley 

 enter rock at 345 to 360 feet above tide. Between these two points borings 

 at Clinton and Montezuma enter rock at an elevation slightly higher than at 

 Terre Haute. The elevation of the rock floor at Shawneetown, Illinois, 

 just below the mouth of the Wabash, is shown by an oil boring to be but 

 240 feet above tide. As this boring was made near the border of the 

 valley, the rock floor may there reach a still lower elevation. 



MINOR DEFLECTIONS OF THE WAHASH. 



At several points the Wabash makes slight deflections from its broad 

 valley to cross projecting points of the preglacial bluff, the most notable 

 instances being just above the city of Vincennes, Indiana, and a few miles 

 below New Harmony. In each place the broad valley of the Wabash 

 passes around the western side of the projecting point, while the stream 

 cuts across in a somewhat narrow valley. It is not entirely certain that 

 these deflections are due to glaciation. Possibly they have been caused by 

 encroachments of the stream upon the rock divides in a maimer suggested 

 in explanation of the deflections of the Mississippi south of the limits of 

 glaciation. The question of the cause of the deflection must for the present 

 remain open. 



LITTLE W ABASH RIVER. 



This western tributary of the Wabash, which drains about 3,000 square 

 miles of southeastern Illinois, enters the river only 8 miles by direct line 

 from its junction with the Ohio. Its source is in the Shelby ville moraine 

 in southwestern Coles County, and its course is slightly west of south for 

 50 miles, to northern Clay County, beyond which point it is east of south 

 through Clay, eastern Wayne, and eastern White counties, a distance by 

 direct line of about 75 miles. Its most important tributary is Skillet Fork, 

 which enters from the west near Carmi. The length of this tributary is 

 about 65 miles, not including the windings of the stream, and it has a 

 watershed of nearly 1,000 square miles. 



The watershed of the Little Wabash, including this large tributary, 





