110 F. V. Hayden—Hot Springs and Geysers 
From such evidence as I could gather, I should estimate that 
under favorable circumstances, at least six feet of the deposit 
have been precipitated within the space of one century. 
There is another interesting feature connected with these 
hot spring deposits, and that is the great antiquity as wellas — 
compactness of some of them. Upon the summits of mountains 
1500 to 2000 feet above the river, and having evidently been 
lifted up by the forces that elevated the whole range, is a bed 
of regularly stratified limestone, varying in thickness from 5) ~ 
to 150 feet, very hard, white and yellowish-white, and appear 
ing in the distance like very pure Carboniferous limestone 
It is evident that this bed of limestone extended over a large 
portion of the valley at one time, for immense masses have broken 
off and are senctaeed. all over the sides of the mountain, even down 
to the river. Near the margin of the mountain there isa belt 
a mile long and a fourth of a mile wide, covered with the 
masses of limestone broken from the main bed. This rock 8 
the hot springs, there is a bluff extending about six miles com 
Secs of 1500 feet, in the aggregate, of Upper Cretaceous and 
ocene Tertiary strata, with some irregular intercalated beds 01 
are} by the hot springs. Underneath the hot spring @ . 
ds of older date incline in the same direction, the angie 
elevates the temperature of the waters of these springs is as 40°? 
seated as is generally supposed, then the heated waters have 
upper 
springs are nearly a thousand feet higher upon the sides of the 
