DOLOMIZATION. Palsy 
The change shown by these analyses is an increase in silica, 
magnesia, and iron in the limestone which forms the walls of the cave, 
and the inference is that this change has been brought about by the 
waters which have formed the cave. A number of analyses were made 
in other places, especially along fractures in the blue limestone on the 
walls of the canyon, where hot springs had evidently recently circulated. 
These all led to the same result as above, and only two more analyses will 
be cited. Of these, the first was taken from a watercourse in the blue 
limestone where the rock was close jointed and had the appearance of the 
Leadville dolomite at Aspen, while the second was taken 10 feet away 
from the first, in hard and unaltered rock. 
Analyses of close-jointed and of hard and unaltered rock from near Glenwood 
Springs, Colorado. 
No. SiO». CaO. Mego. Fe.03. FeO. | 
1 1.96 32.14 18.72 . 03 5833) 
2 2.27 53. 79 - 46 .14 | 
The change in this case is very striking, since the first specimen is 
nearly a true dolomite, while the second is nearly a pure limestone. 
On inspecting the analysis of the water of these hot springs it is seen 
how capable they are of producing the effects of dolomization, silicification, 
and to a less extent of ferration. A noteworthy feature is the presence of 
a large amount of magnesia, which is supposed by Dr. Chandler to occur 
as chloride and as carbonate in nearly equal amounts. It is interesting to 
note, also, that the lime is precipitated mostly in the condition of sulphate, 
although there is also a great deal of carbonate. Both the chloride and the 
carbonate of magnesium are capable of replacing carbonate of lime to form 
dolomite, as has been shown by different chemists, and it is very likely that 
both act together here. 
The phenomena along faults and fractures at Aspen are exactly the 
same as those along similar channels at Glenwood Springs, and the infer- 
ence is that both were accomplished by the same agents. In Corundum 
Gulch, 14 miles from Aspen up Castle Creek, and thus in a nearly opposite 
direction from Glenwood Springs, there are said to be hot sulphur springs. 
In Aspen there are no hot springs, but in the Mollie Gibson mine there are 
