THE LODE, 283 



that the walls are almost everywhere in such close contact, and that the 

 only large opening due to mere relative displacement of the walls is that 

 occupied by the Gold Hill bonanza. If the theory of the fault propounded 

 in Chapter IV. is correct, however, this state of things follows as a necessary 

 consequence, for the vein represents only a single parting, and the relative 

 motion between its walls is the relative motion of two successive sheets. 

 The actual amount of displacement must depend on the thickness of the 

 sheets, which on the Comstock is certainly not above twenty-five feet. This 

 would answer to a relative movement of the actual walls of something like a 

 hundred feet. The opening of the vein in Gold Hill is probably in part 

 attributable to the character of the foot wall, which, being stratified at an 

 angle to the Loue, would be, as all experience shows, less rigid and less 

 easily split into sheets. The dip of the west wall in Gold Hill is also con- 

 siderably smaller than in Virginia, about 10° less, and this fact must have 

 had a tendency to ease the pressure in the southern mines. 



Influence on the path of rising waters. — On accouut of the Small relative movemcnt 

 of the walls of the Lode these are sometimes found nearly or quite in con- 

 tact with one another over considerable areas; and at points where the walls 

 are perceptibly, but not distantly, separated the intervening space is often 

 closely packed with clay and rock fragments. The vein is therefore not an 

 open water channel throughout, and it is highly probable that on some 

 straight or sinuous line it may be impenetrable to liquids from one end to 

 the other. With the east country rock the case is different. As has been 

 noticed frequently in the foregoing pages, it shows an endless number of 

 partings parallel to the Lode and innumerable fractures across the sheets. 

 Few of these partings show any clay, and as capillary fissures can never be 

 stopped except by plastic matei'ial, there is little obstruction to the circula- 

 tion of water in the country rock. This condition of things has most likely 

 had not a little to do with the deposition of ore. The waters, rising from a 

 depth which the heat relations show must be measured in miles, were pre- 

 vented from following the Lode fissure and were forced to permeate the coun- 

 try rock, reaching the open spaces of the vein laterally, and there depositing 

 the quartz and ore minerals dissolved. 



Partial section on the jsoo-foot level. — The uorthei'n miucs Were accessible on the 



