132 THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 
and the channel opened, so that a very good idea can be had of its strue- 
ture. 
This lava flow has long been known and has excited much attention, not 
only on account of its peculiar features, but because of its richness in gold. 
It has already been referred to as having been described by Dr. Trask (page 
68) in his Report for 1856. Mining was commenced under this flow in No- 
vember, 1854, the first discovery having been made, it is said, near Shaw’s 
Flat, by the Brown boys, who in cleaning up an old shaft struck gravel, which 
although only one foot in thickness was very rich in gold. Two years later, 
judging from Dr. Trask’s description, there must have been a good deal of 
activity displayed here. The region was examined by the writer in 1861, 
when work was going on at several places; when revisited, ten years later, 
there seemed to be nothing more doing. All the tunnels, between Shaw’s 
Flat and Jamestown at least, had been abandoned. Mr. Rémond also in the 
course of his examinations near Sonora, in 1866, made two sections across 
Table Mountain. <A description of the principal features of this lava flow will 
be found in Geology, Vol. L, with some sections illustrating its structure and 
peculiarities. 
The fact that the Sonora Table Mountain formerly extended over what is 
now the canon of the Stanislaus was early recognized by the miners, and is 
so evident that it could not escape their attention. To one standing on the 
summit of the mountain at the point of crossing, where it first passes from 
the west to the east side of the river, and looking from either side over to 
the other, the evidence of a former junction of the dissevered portions seems 
to be very clear. There is no mistaking the fact that the portion on the 
west once connected with that on the east. After crossing here, the flow 
continued on for about two miles in an easterly direction to a point near 
where the present town of Springfield is situated, then turned and ran a little 
east of south in a line nearly parallel with the present Stanislaus, for about 
ten miles, to a point a little west of Montezuma; here it divided into two 
portions, of which one ran west for four or five miles and again crossed what 
is now the cafion of the river and continued down on that side, while the 
remainder seems to have kept to the east of the present river. From Mon- 
tezuma downwards, however, the current spread out over such a wide area, 
and has been so much eroded away, that the original form of the flow could 
not be restored without much more labor than we have been able to bestow 
upon it. From the diagram which is here given (Plate D), however, a good 
