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 ; 



(G.) 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 to the rod. The gravel at the lower end of the deposit resembles 

 the gravel at Alpha in appearance, being of a light color, and irregularly interstratilied 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 

 cold 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 



s 



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, 

 I 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 



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