THE SCIENTIFIC MONTHLY. 523 
flexed under the slowly acting pressure, without breaking. Metamorphic rocks are . 
always displaced and folded, and ne\er for any considerable distance horizontal. A. 
Where the foldings are most numerous and abrupt, reducing the strata to a series 
of parallel dips by the pressing of fold upon fold, then the metamorphism is most 
complete.”— Dana. 
In the United States thermal springs correspond exactly with these corruga¬ 
tions. Corrugations do not exist on the plains of the Atlantic coast nor in the 
Mississippi region. Neither do thermal springs. 
“ The single locality in Arkansas is referrable to the Orchean Ozark corruga¬ 
tion. We may consider the heat of springs in the Appalachians due entirely, 
as argued by Rogers, to the normal, we might almost say static, downward in¬ 
crease of temperature brought to bear by means of deep-seated water courses 
following faults and curved strata.”— Gilbert. 
Accepting the volcanic theory in regard to hot springs, we would naturally 
expect that the waters would be the warmest in the regions of latest geological 
formation. And such is in fact the case, as the following table of some of the 
thermal springs in the United States will show: 
