| OCR Text |
Show 74 RECONNAISSANCE IN THE UTE COUNTRY. spathic granite, including a bed of rose quartz twelve feet thick. The lower portion of the caiion is traversed with numerous quartz- veins, but none were discovered bearing valuable minerals. On leaving the Lake Fork and ascending the right slope of the valley^ I observed the red trachyte porphyry of the preceding march, overlaid fey gray trachyte. I observed an oak, Quercus ganayana, at an elevation of 7,970 feet. From Camp 48 the surface is regular, with outcrops of quartzose rocks, and hills are bespangled with mica. Near Camp 49 were formations of porphyry, gneiss, volcanic tufa, trachyte, iron- ore, pitch- stone, nepheline- dolerite, mica, trachy- dolerite, greenstone trap, and hornblende rock. Below Camp 49 are quartzose rocks on the elevation, and browa trachyte on the slopes. Three miles to the rigbt of Camp 50 is a deep caiion, with walls of trachyte like that observed near the summit of Clear Creek Pass. In front of Camp 51 is a high ledge of brown trachyte like that recorded as seen in the canon near the last camp. The bluffs on the right side of Tumitchi Valley are capped with red porphyry, and along the Ute trail leading to the pass are frequent outcrops of white and yellow stratified clays in horizontal position. These formations seem to be like those found in Lake Mary Canon and in the valley of the Lake Fork of Grand Biver; in fact, in nearly every principal valley that came under my notice. Tumitchi Valley is broad and fertile, and affords grazing for several thousand head of horses and cattle, sheep, and goats of the Utes. After leaving the valley, the ascent toward the pass is uniform, the soil dry, and grazing indifferent. In the vicinity of Camp 52 is an outcrop of gray granite. The contour of the surface is comparatively regular to near the summit of the pass, with but few exposures. The elevation of the summit deduced from one observation was 9,834 feet. From the summit down on the Atlantic slope to the Saguache Valley the surface is precipitous and broken, the effects of a deluge of volcanic trachyte. This deposit seems to be identical with that observed near the summit of Clear Creek Pass, in the caiion near Camp 50, and in the ledge near Camp 5L The volcano that emitted these deposits must have been one of great force and in active operation after the surface had nearly attained its present form. During most of the march down the valley of the Saguache the slopes were composed of trachytes. Fragments of white clay like those noticed in the Tumitchi Valley were frequently observed at high elevations. On the left side of this valley opposite the upper end of the cut- off road is a formation of coarse gray sandstone of recent date, occupying 60 feet of the lower slope of the mountains. As the valley widens and gradually merges into the San Luis Valley, the walls on the west side are wholly of igneous origin. Near Camp 55, the valley is several miles in width, and a small portion of it is under cultivation, aided by irrigation. The yield of wheat is probably seven or eight bushels per acre, and is of superior quality. Oats, barley, and potatoes yield large returns, and are of unrivaled excellence. Grazing is also good. Four miles below Camp 55 we enter San Luis Park, arid the march then continued along the west margin. A few points of the mountain-slopes approached neir enough for examination, and were found to be of |
