CHANGES OF DRAINAGE IN SOUTHWESTERN INDIANA. 103 



The bluffs close in on either side of the creek near the center of sec. 19, 

 sloping gradually to the border of the stream. The stream has cut a notch 

 nearly 100 feet in depth across the col. It soon enters a small preglacial 

 valley, but appears to follow the course of that valley for only a short dis- 

 tance. Its course for about 8 miles is mainly across rock points and low 

 divides and lies just outside the glacial boundary. At its junction with 

 Beech Creek a preglacial valley is found, but the stream turns out of this 

 valley in sec. 9, T. 7, R. 4 W., and takes a direct course westward through 

 a gorge, thus cutting off a rock point on the south side of the preglacial 

 Beech Creek Valley. It reenters the old valley near the corners of sees. 

 7, 8, 17, and 18, after traversing a gorge for about 1J miles, and is 

 reported by Siebenthal to continue in a preglacial valley to its mouth. 

 The stream lies within the glaciated region throughout the portion below 

 the mouth of Beech Creek, but is only about 5 miles by direct line inside 

 the glacial boundary at its entrance into White River. It seems probable 

 that the stream discharged through the low glaciated districts bordering 

 White River, even at the maximum extension of the ice, for no line of dis- 

 charge is ftmnd across the elevated districts outside the glacial boundary. 



In the head-water portion of Richland Creek, above the point of deflec- 

 tion from its preglacial valley, there appears to have been a glacial lake for 

 which Siebenthal has proposed the name Lake Richland. The presence 

 of the lake is shown by terraces and deposits of silt and sand which filled 

 the valley up to a definite level. They stand nearly 100 feet above the 

 creek at the point of deflection, but in passing up the valley they gradually 

 approach the creek level, being but 30 or 40 feet above the stream in the 

 vicinity of Whitehall. Whether they are perfectly horizontal has not been 

 determined. The lake apparently extended up the creek a short distance 

 into Monroe County. 



About 4 miles south from the point where Richland Creek turns west- 

 ward into the glaciated district the glacial boundary comes to the west end 

 of another glacial lake whose site is now known as the "American bottom." 

 It extends eastward about 5 miles from the glacial boundary and has an 

 average width of nearly 1 mile. This old lake bottom now has subterra- 

 nean drainage southwestward through sand deposits to a tributary of Clifty 

 Creek, where it appears in the form of springs. Because of the subterranean 

 drainage the plain is preserved in nearly the condition left by the lake. 



