48 



Indiana University Studies 



The middle and upper part of this valley became the site of 

 a lake into which the waters came from all sides, bringing 

 in silt and filling the valley back of the outwash dam to a 

 height of approximately 650 feet above sea level. The con- 

 clusion has already been stated that the valley has never been 

 overflowed by the confined lake waters. It would seem that 

 the waters may easily have filtered thru the sand deposits 

 into the ravines to the w^est, in the lower part of the old 

 valley. These ravines now contain streams of considerable 

 volume due to the constant seepage of water from the sand 

 at the foot of these steep slopes. 



Ashley in his discussion of the stratigraphy of Greene 

 County has the following to say in reference to the 

 Pleistocene : 



In the lowlands and prairies the deposits are found to be of con- 

 siderable depth, often over 100 feet, these places evidently being old 

 valleys filled up. Some interesting deposits occur along the glacial 

 border in eastern Greene County. As the ice pushed its way southeast 

 across the country it overran the lower course of many of the streams 

 flowing west into White River, thus effectively damming them up. 

 Small lakes were thus formed. In time these filled up. Then the ice 

 retreated and the streams resumed their old channels. In most cases 

 they immediately began clearing this lake-deposited material out. As 

 this was in the upper part of their courses where the current had some 

 power, most of the streams have about rid their channels of all vestiges 

 of these deposits. Along Richland Creek in Beech Creek Township, 

 however, much material yet remains in the form of gravel terraces 

 mantling the bluffs of the banks of the streams. In places these ter- 

 races are over one-quarter of a mile broad. In the case of a branch 

 of Cliffy Creek in the southeastern part of Center Township, instead 

 of clearing out the deposit layed down in the ice-bound lake, the water 

 finds its way down through the mass at several places and flows away 

 underground to appear in the old channel farther down. In this case 

 it would appear quite possible that the water found a passage under 

 the ice before the glacier retreated. The result is a flat filling in a 

 valley to which the name of ''American Bottoms" has been given." 



Leverett, following Siebenthal's notes, has the following 

 to say about the ''American Bottoms" : 



About four miles south fromi the point where Richland Creek turned 

 westward into the glaciated district, the glacial boundary comes to the 

 west end of another glacial lake whose site is now known as the "Ameri- 

 can Bottom". It extends eastward about five miles from the glacial 

 boundary and has an average width of nearly one mile. This old lake 

 bottom now has subterranean drainage through sand deposits to a tribu- 



13 23rd Annual Report of the Department of Geology and Natural Resources of Indi- 

 ana, 1898. Pp. 768-69. 



