G. P. Becker— New Feature in the “Comstock Lode.” 461 
syenite, (which in Virginia is plutonic,) the propylite, and the 
vein matter emanated successively from a single fissure in the 
earth’s crust, a lowest point in the contact between the underly- 
ing syenite and the overlying propylite must eventually occur, 
from which the fissure would naturally descend toward the seat 
of the force by which it was caused. ‘From the most depressed 
point in the contact surface, the fissure would pass into the un- 
derlying, or syenite rock, and doubtless out of it farther below, 
into whatever might underlie it in its turn. 
From the point where the fissure leaves the contact between 
the two species of rock, its dip would in all probability be con- 
trolled by circumstances very different from those which de- 
cided it in the position lying near the croppings; for from the 
point at which the seismic shock impinged upon the lower sur- 
face of the syenite, the fracture must have followed the direction 
of least resistance, or presumably a straight line, and the shortest 
line from the point in which the subterranean force encounter- 
ed the syenite, to the upper surface of that formation; and a 
moment's thought will serve to show that, apart from local and 
altogether incalculable irregularities in the lower surface of the 
tock, this line could continue in even approximately the diree- 
tion of the present dip, only in case the syenite not only formed 
4 cone above the general level of the country, but filled a vast 
depression below it as well. The passage of the lode into the 
syenite would therefore naturally be accompanied by a change 
. 
i dip, toward the perpendicular. 
ty, have reached the point at which the fissure passes from 
s 
from 1500 feet, , 
_ The details of these observations would scarcely be of general 
ae away from the Pacific Coast, while ae ogra i le 
will pn : mply justified by the following 
0 on egal meine = 4 2 ere eo ane 
struck between the nort 
end of the “ Ophir” and the south end of the “ Chollar Potosi,” a 
of over a mile, is syenite; that in the three mines, of 
the eight within these limits, in which for fear of water the East 
