266 GEOLOGICAL SURVEY OF THE TERRITORIES. 



it in beautiful curves. On the nortli side we have very extensive de- 

 liosits of gypsum, which, I think, occur in irregular masses. I think 

 they are in rocks of Carboniferous age. North of Frying-Pan Creek 

 there are broad-topped hills reaching just above timber-line, in which 

 we have exposures of red sandstones dipping a few degrees west of 

 north. A section made from these hills northward is shown in Fig. 3, 

 Plate XIX. There seems to be a series of faults. The section was made 

 from the summit of the red hills and may, perhaps, have to be modified 

 in some of its details when the region shall have been more closely 

 studied next season. Just above the canon on Frying-Pan Creek there 

 are exposures of red sandstones, on the south side of the creek, dipping 

 nearly west at an agle of 25° to 40°. These beds are, I think, the di- 

 rect prolongation of those seen on the east side of Eoaring Fork near 

 the mouth of Castle Creek. The gypsum-beds extend some distance up 

 the creek, and in the valley there are several cold sulphur springs. The 

 first one we met with was near the creek, and about 20 feet by 30 feet, 

 with a deposit of sulphur at the bottom. The water is colder than the air, 

 and tastes of the sulphur, although not disagreeably. The next spring is 

 about three-quarters of a mile farther up the stream, and is much smaller, 

 being only about 4 feet in diameter. The water here is also cold, and has 

 a much stronger taste. In the hills on the north side there are outcrops of 

 blue laminated limestone and greenish shales, mostly micaceous. These 

 I believe to be Carboniferous. I did not have time to make a section. 

 The north fork of Frying-Pan Creek, just before joining the main stream, 

 cuts a canon in a blue limestone, in which I found some corals. These 

 limestones, I think, belong to the base of the Carboniferous. They dip 

 a few degrees west of north, at an angle of 20°. Below this blue lime- 

 atone, which is exposed on both sides of the creek, there are yellowish 

 limestones, followed by dark limestones that are cherty and have frag- 

 ments of crinoidal stems. These are succeeded by very compact light- 

 blue limestones, below which we find pink and white quartzites, which 

 rest immediately on the schists. On the north fork, for a short distance 

 above the small canon, to which I have just referred, there is an open 

 valley. Above this valley, the stream is in a very rugged canon in 

 gnessic rocks, there being on the hills exposures of sedimentary rocks, 

 dipping west of north at an angle of about 10°. Just below the canon 

 there is a small creek joining the North Fork on the west side. Here 

 there have evidently once been warm springs, from the abundance of 

 calcareous tufa seen in the course of the creek. A short distance up 

 the creek there is a low bluff, composed almost entirely of the tufa. 

 It is now overgrown by low bushes. The water in this creek has an 

 alkaline taste. In the rocks that we referred to in the preceding chap- 

 ter as curving around the end of the Sawatch range north of the Mount- 

 ain of the Holy Cross, we doubtless have the continuation of those seen 

 crossing Frying-Pan Creek, and which we have just described. In the 

 valley of Frying-Pan Creek, above the North Fork, we have no sediment- 

 ary beds, except those just mentioned. The valley is filled with bowlders 

 of a granitic i)ori)hyry, exactly like that seen in Lake Creek Canon. At 

 Massive Mountain, northwest of which the creek rises, we have schists. 

 These, however, were described in the previous chapter. From the head 

 of Frying-Pan we crossed to the Arkansas Eiver, and visited the Holy 

 Cross Mountain, after which we retraced our way to Colorado Springs, 

 and thence to Denver. The facts noticed there have already been em- 

 bodied in the report. We reached Denver on the 23d of October, and 

 there disbanded, our work for the season being finished. 



