266 GEOLOGY OF TONOPAH MINING DISTRICT, NEVADA. 



Tonopah ma} 1 be as great as at the Comstock, where it is 1 F. for each 33 feet 

 vertical of extent. 



The decided and characteristic curve in the Ohio Tonopah has no counterpart 

 in any of the vertical sections at the Comstock. It is probably, however, a local 

 deviation in a curve of vastly greater magnitude; though its form suggests a con- 

 duction curve, and it is possible that the extremely rapid increase of heat at the 

 bottom indicates the proximity of a local heat focus, such as a hot spring. The 

 larger and much less rapid conduction curve of the Sutro tunnel section is due to 

 the heat from a similar local focus the hot waters which rise along the lode. 



