Oi 
falls. Some of the larger tributaries reduced the lower parts of their 
courses with sufficient rapidity to prevent the development of extensive 
subterranean drainage beneath them, but this was not true of the smaller 
ones lying on the limestene plain. When the !arger streams left the smaller 
ones hanging high in the air, subterranean drainage began in earnest. The 
Tig. 16. Weimer Spring, Bloomington Waterworks. 
rocks were saturated with ground-water and near the mouths of these. 
streams was under an unbalanced static head of about a hundred feet. 
This water gradually flowed into the deeper valleys and was in turn re- 
plenished by more from above, and active underground drainage began 
and concinued in the manner already indicated, 
[720988] 
