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SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION, 





In regard to these stations a few words of explanation are needed : (1) the point visited on 

 Plug Ugly Hill in 1879 was not the same as the 1870 station, — in both instances I looked for the 

 average westerly rim-rock only ; (2) a similar remark may be made about the Little York bed- 

 rock ; (3) the Little York store of 1870 has been destroyed by fire, and my point of observation 

 in 1879 was a few rods above the old site, perhaps six or eight feet higher in altitude; (4) the 

 two points at Empire Hill were certainly not the same, though not far' apart ; (5), (6), and (7) in 

 the last three cases there was a very close approach to identity of position. 



I tried also to get a fresh value for the altitude of the old cement mill at the Indiana Hill out- 

 let, but could not fix upon the exact spot at which the old observation was taken. The altitude 

 in 1870 was made to be 2,792 feet. In 1879 I made the altitude of the bed-rock at the Indiana 

 Hill claim, about a quarter of a mile northerly from the old mill, to be 2,779 feet. If this deter- 

 mination could be trusted to within a few feet, it would indicate a downward grade of the bed-rock 

 towards the north, in opposition to the general pitch of the rock between Indiana Hill and Dutch 

 Flat, which is certainly towards the south, as will be seen later. There is also some evidence 

 of a northerly direction for the channel at this point in the way that the pebbles of the gravel 

 lie against each other; and, indeed, within a distance of 450 feet, the rock exposed to view docs 

 fall to the north as much as six or eight feet. On the other hand, as I was informed by Mr. J. L. 

 Gould, the superintendent of the Gold Run Ditch and Mining Company, there is a rise of bed-rock 

 again, amounting to seven feet, before the Cedar claim, eight hundred feet farther north, is reached. 

 My own observations made the Cedar bed-rock 2,784 feet above sea-level, or five feet higher than 

 that at Indiana Hill. Mr. Gould told me further that the bed-rock pitches again to the south 

 between Indiana Hill and the old mill. Mr. Uren's line of levels (see further on) still leaves some 

 doubt as to the slope of the bed-rock between the Cedar claim and the old cement mill, the uncer- 

 tainty perhaps arising from bad choice of terminal points. There is no great difference of level 

 at best. 



The next point, in a northerly direction, at which I took an observation for altitude was on the 

 bed-rock exposed in or near the Jehoshaphat claim. I made its altitude to be 2,950 feet, but, 

 according to Mr. E. C. Uren's statement, I was from seventy-five to one hundred feet above the lowest 

 portions of the Dutch Flat gravel, the altitude of which, therefore, ought to be not far from 2,862 

 feet, or eighty-three feet above the bed-rock at Indiana Hill, — a value which is in very close 

 accord with that obtained by Mr. Uren, who, by a recent spirit-level survey, made the deep bed- 

 rock at the point where the old channel crosses Dutch Flat Canon, in front of the Waukcgan 

 claim, to be seventy-seven feet higher than the mouth of the tunnel at the old mill. These 

 points are nearly three and a half miles apart, and the average grade of the channel is but little 

 more than twenty feet to the mile ; less than a quarter of that of the old stream on the San Juan 

 divide. 



The average rim-rock at the outlet of Thompson Hill, which Mr. Uren says is probably a little 

 lower than the point he chose for a starting-point, I made in 1870 tq be 2,848 feet above sea-level, 

 or only fifty-six feet above the site of the old mill, according to the measurements of that year. 

 From all these determinations it is clear that the Indiana Hill outlet is certainly lower than the 

 lowest bed-rock, at Dutch Flat, but not so much lower as we should expect when we take into 

 account the distance between the places. 



In striking contrast to this low grade is the steepness of the pitch along the long axis of Dutch 

 Flat, or Gray's, Hill. Since 1870 deep bed-rock has been laid bare at two points on this lull, one 

 nearly opposite the centre of the town, — the Southern Cross claim ; and the other a few hundred 

 feet farther to the northeast, — the Polar Star claim. The altitudes of the bed-rock at these two 

 claims I made to be, respectively, 3,054 and 3,075 feet ; the latter, therefore, being over two hun- 

 dred feet higher than the low spot on Thompson Hill, scarcely a mile distant. There is no known 

 evidence of a fault in the strata, and nothing in the appearance of the gravel indicates rapids or 

 cascades. Further mining operations may be expected to bring to light some interesting features 

 in regard to the position of the bed-rock. 



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