ee Se ee mc St—(C 
THE DIVIDE BETWEEN SLATE AND CANON CREEKS. 453 
larger scale on Plate U. These maps, based in part upon actual surveys, show the main features 
of the region with a fair approach to accuracy. Some of the details have had to be sketched by 
the eye alone, especially such as relate to the boundaries of the gravel deposits and those of the 
volcanic capping, and I cannot vouch for the correctness of all the minor features. I did the best 
I could with the time and means at my disposal to get trustworthy information. 
The principal points at which mining operations have been carried on, and to which reference 
will be made in the next few pages, are, beginning at the southwest, Council Hill, Fairplay, Union 
Hill, Scales’s Diggings, Iowa Shaft (all lying upon the Caiion Creek slope of the ridge); Poverty 
Hill, Portwine, Grass Flat, Gardner’s Point, Cedar Grove Ravine, St. Louis, Chandlerville, Pine 
Grove, Howland Flat, and Potosi, upon the Slate Creek slope. Big Oak Flat, to which reference 
has already been made,* is also on this ridge, about five miles below Scales’s Diggings and on the 
opposite side of Rock Creek. I did not take time to explore that portion of the ridge, having been 
told that no one was working there, and that the old shafts were filled with water. Reports were 
contradictory as to the character of the Big Oak Flat gravel. It was described to me at one time 
as resembling the gravel of Pittsburgh Hill, and at another time as being “ clean quartz gravel.” 
No satisfactory survey of such a ridge as this can be made in a short trip of a few days’ duration. 
The partial list of places just given, the extremes being about thirteen miles apart, is large enough 
to show that an explorer who wishes to get more than a superficial glimpse of the country must 
rather extend his examination over weeks than compress it into days. Where so much mining 
and prospecting has been carried on in tunnels and drifts, a surveyor’s progress is necessarily slow 
if he undertakes to see all that can be seen in regard to the gravel, its position, its course, and its 
character. I was obliged to pass by many places with only a hasty glance, or no glance at all, and 
my report, in consequence, will lack in fulness and completeness. 
The country rock is mainly slate, though not uniform in character. Where it has been covered 
with gravel, the upper portions of the slate have sometimes been altered in appearance, to a depth 
of several feet. The colors of the upper surface frequently change abruptly, and range from dark- 
blue, through reddish or yellowish shades, to a silver gray, even when the same rock, where ex- 
posed in the deeper cuts and in the tunnels, has a uniformly deep-blue color. The strike of the 
slates where observed was northwest and southeast. The dip was nearly vertical at Portwine, but 
made an angle of about 40° to the east at Scales’s Diggings. 
The volcanic capping upon the crest of the ridge is continuous to within a mile of Scales’s Dig- 
gings. Below this point it is seen only on the higher hills. At Portwine the cap is very narrow, 
and, where the Morristown trail crosses the ridge, is less than 200 feet in thickness. Between 
Portwine and Poverty Hill it becomes much broader and thicker. The most prominent points on 
the ridge are Alturas Mountain and Table Rock, both in the vicinity of Howland Flat. The alti- 
tude of the gap between them, upon the road from Howland Flat to Poker Flat, I made to be 
6,370 feet. I did not go to either summit. There are two kinds of lava upon this ridge. At 
Council Hill, at Fairplay, and at several places near Portwine I observed the lava to be tufaceous 
in character, and to resemble in mineral composition the andesitic lava already described as occur- 
ring in the vicinity of La Porte. The lava of Table Rock is darker in color, solid, and compact. 
The specimens which I brought from the Sugar Loaf, near Pine Grove, and which are doubtless 
the same in character as Table Rock, are called basalt by Mr. Wadsworth. The relations of the 
different lavas to each other I did not have time to study. Some interesting questions have arisen 
in this connection, which cannot be definitely settled without further work in the field. I have 
already alluded to the absence of bed-rock exposures at Poker Flat ; other difficulties will appear 
when I come to the description of the country northwest of La Porte, in the valley of the Feather. 
The Council Hill deposit is near the trail from Scales’s Diggings to Brandy City, and overlooks 
the deep and almost precipitous cafion of Cafion Creek. I estimated the depth of the caiion to be 
1,500 feet, but did not cross it at this place. The southward continuation of the old gravel channel 
* Sce ante, p. 4381. 
