410 SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 
inclined to the opinion that the channel came from the northeast. The long axis of the elliptical 
portion of gravel already worked down to the bed-rock, comprising nearly one hundred acres, has 
the direction S. 30° W. (magnetic), with a gradual fall also in that direction. The bed-rock is 
nearly flat in the transverse direction, showing no signs of a deep central channel or trough. 
From the lower or southwestern extremity there is an uninterrupted outlet for the channel, across 
Scotchman’s Creek, to Alpha. 
The bed-rock exposed to view at Omega is a slate, or a series of slates, which presents some 
remarkable variations in character and color within short distances. If the boulders which now 
cover the bed-rock could be removed, there would be seen a brilliant succession of highly colored 
parallel bands, having a northwesterly strike and varying in thickness from twenty to one hundred 
feet or more. The boulders on the bed-rock prevented my making out the precise thickness of the 
different bands. 
The principal varieties of bed-rock were these : — 
(1.) A light-colored, very fragile, clayey, thinly cleavable slate, with a silvery lustrous surface ; 
(2.) A dark, bluish-black slate, — the two having a strong resemblance to the slates at Alpha ; 
(3.) A light-colored, silicious variety of schistose rock, in which coarse grains of quartz were to 
be seen ; 
(4.) A finer-grained silicious rock, almost silvery or pearly in lustre ; 
(5.) A reddish-brown, thinly cleavable, very fragile rock, irregularly mottled and shaded on 
surfaces of cleavage, — when pulverized on the trail in the mine, it looked very much like scales of 
mica ; , 
(6.) A very fine-grained, almost impalpable, perfectly cleavable clay slate, of a bright pink or 
pinkish white color. 
The most of these varieties were so fragile that I made no attempt to get specimens, excepting 
from the last. 
The gravel at Omega has been known and worked, according to a statement in Raymond’s re- 
port for the year 1874, page 125, since 1853. About the year 1869 the Omega Water and Mining 
Company became the owners of the greater part of the deposit, which they still retain in their 
possession. ‘The name of R. W. Tully, of Stockton, was given me as that of one of the principal 
members of the company. The tailings have been deposited for the most part either in Scotch- 
man’s Creek or Missouri Ravine. The main tunnel is 3,000 feet in length, with an irregular grade 
varying from seven to twelve inches tothe rod. The gravel at the lower end of the deposit resembles 
the gravel at Alpha in appearance, being of a light color, and irregularly interstratified with sand 
and sandy gravel, and here and there considerable layers of pipe-clay, seven or eight feet in thick- 
ness. At the upper or eastern end the gravel in the lower stratum is decidedly blue in color when 
freshly exposed, but it changes very rapidly to a yellowish or reddish tint under the action of the 
atmosphere. The gravel is hard, but not cemented. The blue variety is said to be not so rich in 
gold as some of the yellow. The pebbles and boulders at the western end of the diggings are 
mostly quartz; at the upper end some granite boulders are seen. The banks grow higher towards 
the upper end of the mine, being at present fully 130 feet in height, whereas the average height 
could not have been more than from sixty to eighty feet in the western portion. A thickness of 
from 125 to 140 feet may be expected over a considerable part of the gravel still left standing. 
The Omega Company’s ditch is about twelve miles long, and brings water from the South Yuba 
River. The supply is not sufficient to last all summer. In 1879 washing was stopped by the 
1st of August. The nozzles are worked at present under a pressure of a hundred feet, which is not 
sufficient to cut the gravel away without the aid of drifting and blasting. 
There was no one at Omega from whom I could get any detailed information as to the recent 
yield of the gravel. In Raymond’s report for the year 1874, page 125, it is stated that the Omega 
Company had taken out $500,000 in five years. From Mr. John Goyne, the local superintendent, 
T learned that it used to be the custom at Omega to lay off “claims” one hundred feet square, and. 
that an average yield for a claim was three or four thousand dollars. Assuming seventy feet as an 
