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Show 84 RECONNAISSANCE IN THE UTE COUNTRY. These two formations ( Nos. 3 and 4 of Meek and Hayden's sections) are also prominent along the Republican Fork in Kansas, between the 97th and 99th meridians. There seems to have been a coincidence in the level of the ancient cretaceous ocean on the west and east sides of the mountains, as I found a fragment of No. 3 on the slope of the mountains above Boulder City, at about the same elevation as No. 4 on Ohio Creek. This closes the second condition of the park. To understand the third, it becomes necessary to retrace the line of march back to the junction of Tomitchi and Pass Creek, at an elevation of 8,200 feet, or 600 feet above the cretaceous formation in the valley below. Here we find a white, porous, impure limestone, in irregular strata. This formation is succeeded by others mostly of ashy- gray clay, shales, aud soft slates, until it reaches nearly the level of Cochetopa Pass, or an altitude of over 9,000 feet. These formations seem to be destitute of organic remains, but from their lithological characters would consider them of fresh- water origin, and once filled these valleys and closed the third condition of the park. Subsequently the valleys were reopened, and during the process thick beds of conglomerates were formed, fragment ledges of which may be found along the valleys and in the park by the side of, and overlaying, the cretaceous deposits in escarpments of several hundred feet thick. This constituted the fourth period in the the history of the park. With the exception of the cretaceous formation, the history of this park and its valleys is the history of nearly every valley that came under my observation. Exceptions may apply . to the valley of Slate Kiver, that was once filled up to near upper timber-line with blue slate, including a range in height of several thousand feet. In this formation I found two worn casts of what once might have been Inoceramm. Also Mineral Creek of Las Auimas Valley ; on the west branch of that stream exists a line, compact dark maroon lime- . stone, in thick and regular beds, one thousand feet thick and reaching tup to near timber- line, or an elevation of 11,000 feet. The main valley and Cement Creek near by had been filled to near the same height with yellow and white clays, and slate, and conglomerates at a lower level. That the waters reached this level in the deposition of the formations now viewed in fragments is obvious; but the great difference in the rocks of the same valley is not so apparent. Equally perplexing are the water- marks, so fresh on the face of ledges as if the flood had but just subsided. Such evidence exists in the approach to the Cochetopa Pass from the Atlantic side at an elevation and a level but little below that of the ipass. We do not readily comprehend a common- level attaining such an altitude at apparently so recent a date, but rather that these valleys were once a succession of lakes with cataracts between. In the course of time the barriers were cut down, and left the streams and canons as we now find them. All the phenomena connected with this subject are not solved by this hypothesis; probably volcanic agencies modified the conditions. We have seen in the earlier part of this dissertation that at least one volcano has been in active operation since the topographical features of the mountains assumed somewhat the present form. Others have undoubtedly existed up tc ttiis time. These avenues of molten floods may have deluged portions of valleys at different times, or created barriers in great arteries, and thus flooded large sections, or even the whole system of tributary streams. These valleys were then filled up as we have seen, to bevcut away as the barriers were worn down. |
