DEPTH OF ZONE OF FLOW IN THE EARTH’S CRUST 115 
TABLE IV 
SHOWING THE EFFECTS PRODUCED WHEN COLUMNS OF WESTERLY GRANITE—HEATED 
TO 450°C. AND 550°C.—ARE SUBMITTED TO THE PRESSURE EXISTING AT 
A DeEpTH OF 15 MILES WITHIN THE EARTH’S CRUST 
J 
‘ Depth Equi- 
Pressure . 
No. of Kilos. per | valent to . 
Experiment Heat Lbs. per Sq. Cent. Pressure Time Results 
Sq. Inch Employed 
BUS ais cook 450°C. 96,000 6,750 15 miles | 7o secs. | Holes unaltered. 
No movement. 
Bio so due 450°C. 96,000 6,750 15 miles | 7ohrs. | Holes unaltered. 
No movement. 
BOs ca clot Gone 96,000 6,750 15 miles | 7ohrs. | Holes unaltered. 
No movement. 
As before mentioned, the temperature of 450°C. is that which 
exists at a depth of 9 miles below the surface, while a temperature 
of 550°C. is that which is found 11 miles below the surface. 
Experiment 381 is one the results of which are of especial 
interest, for it shows that under the conditions of temperature 
which exist at a depth of 11 miles below the surface of the earth, 
open cavities in granite—at least those of relatively small dimen- 
slons—wi4£l not close even if the factor of time 1s allowed for by increas- 
ing the pressure over and above that which occurs at a depth of 11 
miles by nearly 50 per cent. 
It is further to be noted that this depth of eleven miles (see 
Fig. 1) is not the extreme depth at which experiment shows that 
open cavities may exist. They may be present at still greater 
depths, but the fact that the steel by which the lateral resistance 
was secured experimentally commences to soften at temperatures 
of a little over 550°C. makes it impossible to push the experimental 
investigation by the method employed, to the study of the deport- 
ment of the rock at higher temperatures, that is to say, at greater 
depths. 
THE DEPTH TO WHICH MINERAL VEINS AND ALLIED DEPOSITS MAY 
EXTEND 
The present investigation seems to have a rather important 
bearing on a question of great economic importance, namely, the 
depth to which mineral veins and replacement deposits may extend 
in the earth’s crust. It must first be noted that the question of 
