Malott: The ''American Bottoms'' Region 13 



the joints has frequently enlarged them to eaves of consider- 

 able size and length, considering the limited thickness of the 

 formation. Ray's Cave, near Ridgeport, is a cave of very 

 uniform width and height, following the joints strictly, and 

 turning frequently at sharp angles. This cave may be easily 

 followed for a distance of about 1,000 feet, to a point where 

 further progress is arrested by a mass of great sandstone 

 blocks fallen from above. This distance, however, must rep- 

 resent only a small part of the total length of the cave, since 

 a large volume of water comes from under the fallen debris. 



Just how important this limestone is physiographically 

 will be clear when it is realized that the peculiar drainage 

 conditions in the ''American Bottoms" are due to its presence 

 at critical levels. Bridge Creek and its smaller associates do 

 not empty their v\^aters into the sandstone bluff for any other 

 reason than that the Beech Creek limestone is immediately 

 below it. This limestone is, in fact, only 10 feet below the 

 point where the waters of Bridge Creek enter the sandstone, 

 tho the limestone itself is nowhere visible about the margin 

 of the ''American Bottoms" flat. Had it not been for the 

 presence of this 20 odd feet of limestone at this particular 

 level, there could have been no subterranean drainage, such 

 as occurs, nor could there have been preserved the unusually 

 broad, filled valley, which, for the most part, is wholly intact. 

 The physiographic effect of this limestone at a critical level 

 is seen again in the southwest quarter of section 35, along 

 Cliffy Creek, where the limestone has been carried by the 

 dip to slightly below the level of the stream, permitting the 

 local development of subterranean drainage by the waters of 

 Cliffy Creek. Only the flood waters pass around the great 

 double meander at this point. The water passing thru this 

 subterranean passage, or rather passages, along the enlarged 

 joints in the limestone is lost to view for a distance of about 

 one-fourth of a mile, and nearly 150 feet beneath the crest 

 of the ridge above. This underground passage-way of Cliffy 

 Creek is in its initial stage, but we can see that it must 

 finally cause the complete abandonment of the surface chan- 

 nel, leaving the great double meander of a dry valley sunk 

 deeply into the strata, the product of a stream which has 

 entrenched itself since the invasion of the Illinois Glacial Lobe 

 into the region (see Fig. 2). 



