238 B, Silliman on the Grass Valley District. 
yet farther south. There is probably a saddle or anticlinal axis 
below the Allison Ranch mine, due to the elevation of the syen- 
itic mass, which, it seems probable, sets in at the sharp bend in 
the stream, before alluded to, and where the ravine trail joins 
it. The stream probably runs pretty nearly in the basin of the 
synclinal. 
The rocks on the east side of Wolf creek, and above Forest 
Springs locations, dip westerly. Such is the case at Kate Hay 
and with the veins on Osborn Hill. The middle branch of the 
dips southerly, in a direction exactly opposite to that of the 
North Star, there being a valley between the two, and a saddle 
or anticlinal between Cincinnati and Massachusetts Hills. 
These facts, which, by a more detailed statement, could be 
and dip of the Grass Valley vein is es ially conformable to 
that of the rocks, and that the streams Sane in general, exca 
vated their valleys in a like conformable manner. 
€ quartz veins of Grass Valley District are not generally 
large. Two feet is probably a full average thickness, while 
while at the same time there are veins like the Eureka which 
have averaged three feet in thickness, and the Union Hill vem 
over four feet. The Grass Valley veins are often, perhaps us® 
ae abedded in the inclosing rocks, with seldom a fluecat o 
clay selvage or parting, although this is sometimes found 0B oe 
of —_ walls. The walls of the fissures and the contact faces 
of the veins are often seen to be beautifully polished and 
_ The. veins are, as a rule, highly mi : stalline, 
afford ’ t ghly mineralized and crysta 
_ Hord the most unmistakable a of an origin from solu 
Gialagings » and not the least evidence of an igneous origi? 
ous features nee and agatized structure are very consple! 
tive of the cold reeset the best characterized and most produc 
ive of the gold-bearing veins of this district. ‘These indisptt™ 
