BETWEEN NORTH BLOOMFIELD AND EUREKA. 101 
which can be supposed to belong to the old channel, whose course I have been following in these 
notes, it will be convenient to put here in tabular form a summary of what has been already written 
in regard to the question of grade of bed-rock. In regard to a supposed continuation of the old 
channel towards the north more will be said when the description of the Forest City divide is 
reached. The tabular statement is given below. 
eee mile 
Be a a er Altitude PiMniude, each Station 
one preceding. 
Timbuctoo 473 feet 
Mooney Flat 2¢ miles 2+ miles (Py elias 284 feet 114 feet. 
French Corral Qierrnss J eee 1,579" $22 “ a 
North San Juan Gan 1Bicn of 2,033 “ 454 “ 67.“ 
Badger Hill 4, « QoL « 2,391 « 356 « 80 « 
Malakoff 7 « 293 « 2,929 « 538 « 72 « 
Derbee Shaft CN 3lz “ 3,303 “ 494 « A 
Watt Shaft eral 342 “ 3,800 <“ 447 “ eS 
Snow Point ae et 382 4,211 “ arr” 103 * 
The average grade for thirty-eight miles and three quarters is ninety-six feet to the mile. The 
most noticeable deviation from the average grade is between Bloomfield and the Watt Shaft. 
Until further explorations are made no final explanation of this deviation can be reached. For 
the present I am inclined to the opinion that there will be found somewhere between Bloomfield 
and the Derbec Shaft, if work is ever so far prosecuted as to make an underground connection 
between the two places, either a fault in the strata, formed subsequently to the deposition of the 
gravel, or else evidence of the former existence of cascades or rapids. This opinion is based 
entirely upon the steepness of the grade at this point, and cannot be, so far as I know, corroborated 
by anything now observable in the rocks. This point will be referred to again in connection with 
the altitude of Relief Hill. 
The bed-rock seen at Woolsey Flat is an easily cleavable slate, whose dip is usually nearly vertical, 
though in some places at an angle as low as from sixty to seventy degrees. At Moore’s Flat the bed- 
rock is also slate, as it probably is at Orleans Flat. The last-mentioned place I did not visit ; the 
ground was worked out many years ago. In the second report of J. Ross Browne, dated in 1868, the 
diggings at Orleans Flat are spoken of as having been abandoned for several years. The bed-rock 
at the Shanghai diggings, which are on the northwesterly extremity of Snow Point, is a very soft, 
easily worked slate, which weathers very rapidly upon exposure to the air to a bluish or reddish 
clay, or else has suffered decomposition to a considerable depth while still covered with gravel. 
About five acres of bed-rock are uncovered at this point, and nearly the same amount on the 
northern slope of the hill. I made no attempt to examine this second exposure of bed-rock, for 
the reason that the diggings have not been worked for several years, and the slides of clay and sand 
have hidden a great part of the rock from view. I was told, however, that a few hundred feet 
to the east of the Shanghai diggings the bed-rock was a very hard slate, — the “ hardest kind.” 
The precise position of the deep channel between Snow Point and the Boston mine cannot be 
given. The Snow Point gravel appears to have its longest axis in an easterly direction, and there 
are some indications of a rim on the northern side of the Shanghai diggings ; but the pitch to the 
south is very gradual, and there is nothing to be seen above Snow Point to lead to the belief that 
any old stream ever came down from an easterly or northeasterly direction. The Moore’s Flat 
bed-rock at my point of observation seemed to be nearly level ; there was no well-defined rim to 
be seen. As before stated, this point was on the northeast side of the gravel deposit, opposite 
Orleans Flat. The gravel had been removed for a distance of from 800 to 1,000 feet back from 
the ravine, where work had to be suspended on account of the tunnels being “ out of grade.” The 
general course of the old channel from Moore's Flat to Woolsey Flat is about S. 20° W. (magnetic), 
but at the Boston mine it is S. 25° E. (magnetic), the deflection towards the south amounting to 
