GEOLOGICAL SURVEY OF THE TERRITORIES. 161 



These beds I took to be Silurian, although I could find no fossils. They 

 were followed by Carboniferous limestones, di|)i)ino' un(;onforihably be- 

 neath theni at an anj»le of 50°. This unconforinability was caused, 

 most likely, by the force ot u[)heaval. There appears to be a complete 

 inversion of the strata, which a few miles farther up the river we saw 

 almost vertical, but dipping northeast. On the opposite side of the 

 river I found quartz-schists, but they were so coveretl by detritus and 

 the timber that very little could be determined in regard to them. I 

 will lefer again to the inversion of the strata fuither on. 



The middle canon is seventeen miles long, and its direction from the 

 upper end to the creek, where I found the inverted strata, is northwest. 

 Here, however, it takes an abrupt turn toward the west, almost at right 

 angles to its former direction, and is cut through chloritic and gneissic 

 rocks. 



On the 27th we camped just outside the canon, and from this point, 

 in comi)any with Messrs. Gannett, Holmes, and Savage, I made a trip 

 through Eaynold's Pass to Henry's Lake, and thence across the divide, 

 again to the valley of Eed Eock Lake. The metamorpbic strata still 

 continued dipping southwest. At Taghee Pass, east ot Henry's Lake, 

 I believe they are capped with Carboniferous limestone. Eaynold's 

 Pass is low, only 0,911 feet in height. The ascent is very gradual, and 

 it is diflicult to determine exactly where the stream runjiing into 

 the Madison ends and that running into Henry's Lake begins. 

 To the southwest of Henry's Lake I noticed in the distance a 

 volcanic range. This section of country, however, will probably be 

 fully treated of by Professor Bradley, and I therefore pass it. The 

 divide between Henry's Lake and Eed Eock Lake is 7,271 feet high, the 

 distance between the lakes being about eight miles. On the Eed Eock 

 side of the divide I found in the valley of a small stream an excellent 

 exposure of reddish quartz schists, the thickness of which 1 estimated 

 at about 2,000 feet. 1 am of the opinion that they rest immediately on 

 the granites. They dip southwest at an angle of 20°. Viewed from a 

 short distance the out-crop has the api)earan(;o of a huge staircase. 

 Between Eed Eock Lake and the Madison Valley the ibrmations are 

 mostly modern, mingled v.ith igneous rocks, the exact relations of 

 which 1 had not time to determine carefully. 



Alter leaving the middle caiion, the Madison Eiver makes another turn 

 of nearly 90° toward the north, and when we reach the point a short dis- 

 tance below, near Indian Creek, we find the limestones which we saw in 

 the middle canon again making their appearance. 1 made several trips 

 into the Madison Eange, one above Indian Creek, one at Bear. Creek, 

 and a third up Jackass Creek, at the lower end of the valley. Above 

 Indian Creek I found the ridges and peaks made up of mica-schists, 

 which were so covered with detritus that little could be determined in 

 regard to them. We had a great deal of bad weather about this time, 

 which also interfered much with my work. Among the specimens I 

 obtained are aplite, micaceous gneiss, and quartz. Bear Creek is a 

 small stream, joining the Madison on the riglit side, about forty-eight 

 miles below the canon. The rocks at the mouth are hard blue and yel- 

 low limestones, containing fragments of corals and crinoids. These I 

 take to be either Upper Silurian or Devonian. The layers are very 

 much contorted, but the di|) is about west, or, perhaps, a little north of 

 west ; angle, 20° to 30°. These beds are followed by dark-blue Carbo- 

 niferous limestones, containing Strophomena, Sjjirifer, FrodiicUis, and 

 Ortlm. 



11 G S 



