Origin of the Caves — Kraus. r69 
For our consideration it is important that there is actu- 
ally an increase in volume when anhydrite becomes hy- 
drated and concerning this point there can be no question, 
whatever, as the cores from the Schiele well furnish the 
best of evidence. Furthermore, all the authorities, cited 
above, agree that this increase is sufficient to exert enor- 
mous pressure directed upward, and also, that the disturb- 
ances, which are generally encountered in the rocks overly- 
ing gypsum deposits, are to be referred to such a cause. 
Bischofif* and Crednert cite many instances where disturb- 
ances have been noted. Among the various localities, 
-which are mentioned by the former, we find especial refer- 
ence to two American sections, namely Oneida and Onon- 
-daga counties in the state of New York, where very pecu- 
liar conditions of the strata exist. In these localities very 
considerable deposits of gypsum occur — in some instances 
as thick as 60 or more feet. 
There is no question as to the enormity of the force 
•exerted by freezing water and yet, the increase in volume, 
•caused by the water passing from a liquid to a solid con- 
-dition, is but 9 or 10 per cent. It has, nevertheless, been 
■estimated that the force thus exerted is no less than 138 
tons per square foot^ or 1,916 pounds per square inch. Thus, 
we find, if we consider the lowest figures, given above, as 
correct for the increase in volume accompanying the change 
from anhydrite to g}'psum, namely 33 per cent, that this 
increase is more than three times that indicated above for 
freezing water, and hence, a much greater force would 
necessarily be exerted, even if the compressibility of gyp- 
sum be somewhat greater than that of water. In this con- 
nection both BischofT and Credner say that this increase 
in volume is the cause of the uplifts, folding, and faulting, 
which are so commonly noticed in the overlying and ad- 
joining strata — a phenomenon which formerly gave rise to 
the notion that gypsum was of eruptive origin. Dana. 
Geikie, Prestwick, and many others also indicate the fact 
that the hydration of anhydrite is usually accompanied by 
local disturbances. 
• Chemische Geologic II. 188-197. 
t Geologic 8te Auflage, 1897, 200-201. 
X Brigham, A text-book of Geology. 1902. 24. 
