87 
since there is evidence that collapse has brought the present stream to the 
surface for some distance below the “Gulf” where it now escapes. 
The collanse of the mouth of the cavern is brought about by the in- 
creased width and height due to solution and abrasion, the fall of slabs 
Tig. 6. Stony Spring, Bloomington waterworks. During freshets the water 
flows out all around the foot of the bill shown in the picture and even farther to 
the left. The cavern containing the stream is here collapsed, blocking the outlet. 
When the cave fills with water it breaks out wherever it can find an opening. The 
water comes from the former drainage basin of Indian Creek and now enters the 
head of Clear Creek. 
from the roof and by the lowering of the channel until the roof, unable to 
support itself, finally falls. This collapse of the lower portions of caverns 
bringing more and more of the subterranean stream to light may be, and 
frequently is, going on at the same time tbat the upper reaches of the 
stream are being converted from surface into subterranean drainage. This 
is true of nearly all the largest outlets of subterranean drainage in the 
Bloomington region. Stone spring at the Water Works, Shirley spring and 
Leonards spring, southwest of the Water Works, and Blairs spring, just 
northwest of Stanford Station, all show this phenomenon, while the upper 
