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Indiana TJniversitij Studies 



minor nature thruout the Mississippi valley. The chief move- 

 ments that have occurred since the middle Pleistocene have 

 as a whole been slightly upward, tho there are some indica- 

 tions of tilting. Everywhere beyond the influence of the con- 

 ditions which gave rise to valley filling, the present streams 

 are cutting their valley floors. It appears that instead of 

 the valley-fill material gradually thinning out up stream, it 

 thins rather abruptly, and streams are cutting their bed-rock 

 floors where they might be expected to have filled valleys. 

 The Cumberland River illustrates the general condition, Near 

 its junction with the Ohio River, this stream valley is filled 

 not less than 175 feet deep, but in the vicinity of Nashville, 

 Tenn., barely more than the beginning of its middle course, 

 the stream is eroding its bed-rock floor. Numerous other 

 similar instances might be given. This condition indicates 

 that uplift has been differential or that tilting has occurred. 

 This condition is not out of harmony with the principle of 

 valley filling due to the extension of the Mississippi River by 

 delta building. 



Geneial View of the Topography and Relief before the 



Adverat of the Illinois Glacial Lobe. Near the close of the 

 pre-glacial physiographic development of the ''American Bot- 

 toms" region, the ridges between the deep stream valleys 

 probably appeared somewhat as they do now, tho perhaps 

 slightly broader. The area was sharply trenched by the main 

 streams, and their ravine-like tributaries began with rather 

 abrupt, steep gradients, as they do today on the south side 

 of Beech Creek valley. Ray's Cave spring and all the other 

 springs coming from the greatly enlarged joints of Beech 

 Creek limestone along Beech Creek valley were well developed. 

 A stream valley similar to the upper course of Cliffy Creek 

 valley traversed to ''American Bottoms", and passed to the 

 southwest thru the southeast quarter of section 27, and 

 entered pre-glacial Cliffy Creek near the center of section 34. 

 Cliffy Creek valley, instead of follovdng the tremendous 

 meanders seen in section 35, passed directly west thru sec- 

 tions 35 and 34, and turned southwest into Plummers Creek 

 valley in the northwest quarter of section 4, about one-half 

 mile east of Mineral City. Some 75 feet above the valley 

 of the stream which traversed the site of the present "Ameri- 

 can Bottoms", the Beech Creek limestone outcropped, and 



