REVIEW AND GENERAL DISCUSSION. 49] 
mined in any way, through all the ridges in the country over which my work extended, between 
the North Fork of the American and the Mokelumne River. 
There is a possibility that a channel may run through from Grizzly Flat to the Morning Star 
mine. 
The main channel at Damascus, that is, the “Mountain Gate” channel, appears to be well defined, 
running into the ridge in a direction nearly due southeast (magnetic). How deep this channel 
may be cut in the bed-rock, and how wide it may be across its top from rim to rim, is very un- 
certain. But from such indications as can be seen along the sides of the hills, it seems likely that 
its breadth is considerable, and that the maximum height of its rims above its bed may reach, in 
places at least, from 200 to 300 feet. The barometric observations show that the bed of this 
channel passes through the present hill at a depth of not less than about 800 feet beneath its 
crest ; of which depth the whole mass, with the exception of the comparatively thin layer of 
gravel which fills the bottom of the channel, appears to consist of volcanic conglomerates and 
breccias. 
The accompanying notes will show how far this channel has already been followed in the 
tunnels. But how much farther it may continue to hold its southeasterly course, and where it 
ultimately goes to, are points which remain to be proved, and upon which there are many different 
opinions among the miners. 
The main ridge beneath which it passes in the vicinity of the Forks House is two or three 
miles wide, and there are several possibilities in the case. But I shall add a few remarks on 
this point further on. 
Where this channel came from towards the northwest has also been a much-vexed question. 
The character of its gravel is peculiar, it being by far the purest quartz gravel which I have seen 
in the country, and containing the most numerous and the largest white quartz boulders, among 
which masses of forty to fifty tons in weight are not uncommon. ‘The grade of this channel is not 
uncommonly heavy, and I do not think such enormous boulders can have travelled very far 
along its bed. 
I can only explain their presence here, in connection with a gravel of which the sand as well as 
the smaller pebbles consist almost exclusively of quartz, by supposing that somewhere along the 
course of the ancient stream, at no great distance from their present resting-place, there once existed 
an enormous mass of quartz in the region which has since been excavated to form the tremendous 
cafions of the branches of the North Fork of the American ; and that, while this quartz was broken 
up to form the present gravel, the slates and other rocks which were associated with it being 
softer, and liable also to disintegration by chemical means, were entirely ground to sand and silt 
and completely washed away. 
I am told no indications of the existence of such a channel as this have ever been found, either 
on the opposite side of the North Fork of the river or higher in the mountains among its branches 
to the northeast. But since, in the near vicinity of Damascus, the North Fork of the American 
River splits up into three or four large branches, and the caiions here are very deep and the ridges 
narrow for some distance above the forks, there is a considerable area here in which the ridges and 
spurs, though very precipitous, do not rise high enough to touch the plane of the ante-volcanic 
gravel, and any vestiges of ancient channels which may have once existed within this area have 
since been swept away. Under such circumstances, I think the most probable solution of the 
question, Whence came the Damascus channel? is the supposition that, if we could have fol- 
lowed up its ancient course for a short distance farther to the northwest over the region now occu- 
pied by the basin of the Humbug Cafion and the branches of the river, we should have found it 
then to curve gradually around to the north and northeast and probably to split up into various 
smaller channels, and thus to completely lose both its size and its distinctive character long before 
it would reach any of the present ridges in the higher northeastern country at points where any 
remnants of these branches might now be traced. 
It will be noticed as an exceptional fact that at Canada Hill there seems to have existed a well- 
