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476 



SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION 



The region to the southeast, between Hungarian Hill and Clermont, I did not visit. From 

 Mr. Orr I learned that gravel, which has not yet been prospected to any extent, is to be seen on the 

 surface for a considerable distance to the south and southeast of the Five Points claim ; that, after 

 crossing the low divide between Slate Creek and Rock Creek, gravel is found along the right bank 

 of the latter stream ; and that it can be traced beyond Deer Creek, a small stream which crosses 

 the gravel without cutting down to bed-rock. The high points of the ridge are said to be capped 

 with lava, as, for instance, at the head of Deer Creek, though no lava is to be seen along the line 

 of Orr's ditch for the first five or six miles above Five Points. From Mr. D. L. Flaun, whom I 

 met at Quincy, I learned that, since the date of Professor Whitney's visit to Clermont,* a second 

 tunnel, 800 feet in length, has been driven under the lava cap, on the western side. The gold- 

 bearing gravel channel was found in this tunnel, but the gravel was too thin for profitable 



working. 



The only other points that I visited in this vicinity lie nearer to the base of Spanish Peak, 



at the headwaters of some of the southern tributaries of Spanish Creek. Mumford's Hill, the 



most southerly point reached, occupies the spur between Pig Creek and Eagle Gulch. The 



altitude of Mr. Edman's house I made to be 4,710 feet, which is about thirty-five feet higher 



than the bed-rock at the upper end of the gravel deposit. The bed-rock is, in general terms, 



* 



a slate, with a strike of N. 55° W. (magnetic), though changing very frequently in color, in 

 lustre, and in composition. One striking variety is made up of alternate silicious and clayey 

 layers, the former being from one eighth to three eighths or a half an inch in thickness, while 

 the latter are not more than one third as thick, which, though not distinguishable on a fresh 

 surface, appear very prominently as easily separable layers, alternately light and dark in color, 

 when the rock is exposed to the action of the weather. The effect is very pretty, but cannot 

 easily be preserved in a hand specimen. Directly under the gravel, and forming a part of the 

 bed-rock of the mine, there is a dolomitic belt, or fissure vein with a dolomitic gangue, carry- 

 ing fine gold. The dip of this " ledge " is 60 a to the northeast ; in strike, it follows very 

 nearly that of the enclosing slates ; its average width may be taken as nearly fifty feet. The 

 following description of this peculiar deposit is taken from Mr. Edman's paper in Raymond's 

 Eighth Report, to which reference has already been made. "The vein-stone of this ledge is 

 magnesian limestone, penetrated by a network of small quartz veins, and filled with lumps of 

 talcose slate, rich in crystals of oxide of iron. Through this mass course larger veins of quartz, 

 often swelling to large masses ; it is frequently divided by bands or lenticular masses of an altered 

 talcose slate, impregnated by decomposed sulphurets. Near the walls are often found alternating 

 layers of clay and broken quartz, and a ferruginous quartz-conglomerate. The magnesian lime- 

 stone is decomposed to a great depth, forming a soft, porous mass of brick-red earth, full of quartz 

 and slate fragments, with rounded boulders of unaltered vein-stone reposing therein." The ledge 

 has been worked by an incline to a depth of 100 feet, where the dolomitic gangue is solid and 

 distinctly recognizable. The average yield of this ledge is from three to four dollars per ton ; 

 the richer portions run much higher. The length of the Mumford Hill gravel deposit, between 

 Pig Creek and Eagle Gulch, is about 800 feet, following the general direction of the strike of the 

 bed-rock, until the curve west of Mr. Edman's house is reached. The grade of the bed-rock is 

 towards the northwest. At its upper end the channel is 500 feet in width ; at the lower end, 

 about 250 feet. The eastern rim of bed rock is very steep ; the western rim has a more gradual 

 slope? The banks of gravel average from forty to fifty feet in height. The gravel is made up of 

 different varieties of country rock, intermixed with a little quartz. Neither pebbles nor boulders 

 show many signs of wear. Among the boulders are some of quite peculiar character, which 

 appear to be completely changed to clay ; though the original rock, when sound, is fine-grained 

 and crystalline, as is proved by the finding of specimens in a state of only partial disintegration. 

 The rock in pla'ce from which these boulders come Mr. Edman thinks he has found, at a point 

 about two miles to the south of Mumford Hill. Some of the gravel shows manganese stains. 



* See ante, p. 215. 



/ 





