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THE WASHINGTON RIDGE. 



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altitude, but no bed-rock has been reached. The present bank at one of the most advanced of the 

 openings is 260 feet in height, and, with the exception of eight or ten feet of red dirt and volcanic 

 debris at the top, is made up of alternating layers of sand, clay, and fine gravel, ranging from two to 

 twenty feet in thickness. The material of the gravel and sand is almost exclusively quartz, and there 

 is seldom a pebble more than three or four inches through. The water in the sluices, instead of 

 being reddish in color, as is so common in gravel mines, was nearly as gray as if it carried nothing 

 but tailings from a quartz mill. The lower hundred feet is of a bluish slaty color. There are no 

 boulders excepting those of volcanic material which fall from the top of the bank. Some of the 

 clay streaks are exceedingly rich in fossil leaves and impressions. There is also considerable 

 pyritous fossil wood. The present bank at Gopher Hill is about 240 feet in height. As seen from 

 a distance, the top gravel resembles that at Sailor Flat, just described, but much more free from 

 sand and clay. Lower down the gravel is coarser and the boulders are larger. Towards the 

 bottom the material of the gravel is for the most part metamorphic slate rock, without many quartz 

 pebbles. It has a striking resemblance to the gravel at Smartsville, yet would be easily distin- 

 guished by any one familiar with the appearance of gravel banks. I cannot describe the difference 

 in words, any more than I can the differences of the features of two persons who look alike. The 

 lowest stratum is a hard blue cement. 



leading ( 



At the Enterprise ground, the top bench of light gravel has been removed over an area of about 

 eighty acres. The high bank is there nearly three hundred feet high. At one point in the Enter- 

 prise ground there was a volcanic top-dirt as much as seventy feet thick in the thickest part. It 

 thinned out rapidly on both sides, however, so that the cross-section resembled an old local ravine 

 which had become filled by a slide from the central ridge. 



At Sailor Flat there is no recognizable difference of value between the top and the bottom gravel. 

 The gold is fine and scaly; but at Gopher Hill the bottom gravel is notably richer in gold, and the 

 gold is of a coarser and more massive character. 



. There does not seem to bo much use in trying to trace the course of any old channel at this 

 point until more is known about the relations of the bed-rock. At Gopher Hill I paid some atten- 

 tion to the direction of the principal grooves and furrows in the bed-rock, and found it N. 70° W. 

 (magnetic). This, however, is not an indication of much value. I will add here that in the 

 opinion of Mr. Hughes and of Mr. Chadwick, there are several nearly parallel gravel streams 



lown obliquely from the direction of the main ridge, which did not all concentrate at one 

 point. The data which I collected at New York Canon, and which will be given on a subsequent 

 page, have some bearing upon this view of the question. 



The two sections on Plate 0, Figs. 2, 3, are drawn on the same scale as the accompanying map 

 or nearly so. The north and south section (Fig. 2) extends from the South Yuba River to a point 

 high up on the ridge above the Blue Tent House. It will be seen that if the bed-rock is level 

 from the point " I>," the gravel must be as much as 650 feet thick at the point where the house of 

 the superintendent stands. I do not think that the gravel will prove to be of that thickness for 

 it seems most likely that the bed-rock will begin to rise in harmony with the general slope of the 

 ridge before that point is reached, 



The east and west section (Fig. 3) has one remarkable peculiarity. It shows a profile across the 

 northern end of the deposit, where there is a " high channel " between Gopher Ravine and Johnson 

 Creek, with its bed-rock 145 feet higher than the bed-rock at Gopher Hill. This high channel is 

 said, furthermore, to have carried granite boulders, such as have not been met with yet at other 

 places in this neighborhood. 



In this connection another diagram (Plate O, Fig. 4) may be given to show a section, north and 

 south, through the Sailor Flat mine to the centre of the ridge, I do not have the necessary data, 

 to make the section an accurate one. The heights and distances are estimated, but are fair approxi- 

 mations to the truth. The scale is 500 feet to the inch. The point A is the point on the rim at 

 which, the observation for altitude was taken. The surface on the flat bench above the gravel bank is 

 covered with volcanic debris for a thickness of from five to twenty feet, and there is probably gravel 



