Malott: The ''American Bottoms" Region 



53 



results of the passage of water thru the joints in the sand- 

 stone to the hmestone below, which has been partially re- 

 moved by solution. These sinks are, of course, due to the 

 Beech Creek limestone below, but superficially they give the 

 appearance of being sinks in the sandstone itself, a thing 

 scarcely possible. 



It will be noted by reference to the maps that the entrance 

 to all the inlets into the subterranean passageways lie against 

 the sandstone bluffs at the south side of the valley in a belt 

 running in a general southwesterly direction. A broad, shal- 



FiG, 8. Main outlet of Bridge Creelv waters from beneath the Cyi)ress 

 sandstone, nearly 2 miles southwest of where the waters enter the subter- 

 ranean passage ways. The Beech Creek limestone is here some 10 feet 

 below the surface. Photo.^raph by P. B. Stockdale. 



low sink-hole is the last of the series. In line with this belt 

 and two miles to the southwest are the outlets to these pas- 

 sageways in the Cypress sandstone bluff on the east side of 

 the re-excavating valley from the north. The chief one of 

 these outlets is the middle one, where most of the normal 

 flow comes out in a broad, ill-defined opening from under the 

 sandstone at the very level of the valley floor (see Fig. 8). 

 A much smaller amount of water comes from the outlet at 

 the south, near the road. The opening to the north, nearly 

 one-quarter of a mile north of the road, is the most interest- 

 ing (Fig. 9). It is an opening some 2V2 feet high and about 



