RESUME OF LITERATURE. 113 



upper is in contact with the Archean, should be regarded as evidence favorable to 

 this view. But the strata at this point have a nearly vertical position, and this 

 circumstance suggests that the thinning of the series here may be due to structural 

 causes. The fact that King compares the compact conglomerate, which is the lowest 

 bed exposed, with one "which is interstratified far up in the limestone, as seen 

 at various points on the western slope," would seem to indicate that if an actual 

 overlap the horizon of transgression does not coincide with the top of the lower of 

 the divisions recognized by him, but took place at a higher level. On the whole, I am 

 disposed to consider it more probable that the lower beds belong to the same series 

 as the upper and that all are of Pennsjdvanian age. The paleontologic evidence 

 necessarj' to settle this point one way or the other is as yet unfoi-tunately wanting. 



"Along the west flank, as already mentioned, the series makes a continuous 

 outcrop from the northern limit of the map to a point 2 miles north of the Pacific 

 Railroad, where it is overlapped by the conformable red Trias." "Always next to 

 the Archean series occur the red sandstones, which we correlate with the Black 

 Hills Primordial, presenting- toward the east a rather abrupt, but low, mural 

 outcrop." Hei'e, however, a greater thickness of the whole series is developed than 

 on the eastern side of the range, for it contains beds amounting to 1,200 feet. "On 

 the western side no fossils were obtained from the uppermost members, but distinct 

 Coal Measure types were obtained within 200 feet of the base." The species, which 

 are the same as found to the east, consist of Productus semireticulatus^ Productus 

 costatns, Productuti cora^ Seminida suhtilita., Bellefroplion sp., and Ortlioceras sp. 

 Much the same sei'ies, apparentlv, occurs at several points in the Medicine Bow 

 Range, but at Rawlins Peak is one which leather suggests that in central Colorado. 

 At the base is about 700 feet of gray and white quartzites and sandstones, the 

 uppermost bed being a ferruginous sandstone 1.5 feet thick. These are suggestive 

 of the Sawatch quartzite. The drab lithographic and white siliceous limestone next 

 above may possiblj' represent the Yule limestone, while the dark blue, earthy 

 limestone with Pleiurophorus ohlongus and Productus, both as to color, position, and 

 fossil content, shows points of resemblance with the Leadville limestone, in which 

 Whitfield identified PI. rihlongus at Leadville." The gap of 500 feet not far above, 

 which is supposed to be largelj* made up of calcareous and argillaceous beds, 

 possibl}' represents the Weber formation. "Above this is another gap, without 

 outcrop, of 100 feet, limited above by the distinct and characteristic Triassic beds."'' 

 Apparentlj" in the Triassic near its base was found the species Natica % lelia, which 

 King believes to indicate the top of the Permian, but which is now generally placed 

 in the Mesozoic. Considered by itself, this species can hardly be allowed much 

 diagnostic force, and from this locality, at all events, no associated fauna is known. 



nU.S.Geol.Surv.,Mon., vol. 12, 1886, p. 66. i-U. S. Geol. Expl. 40th Par., Rept,, vol. 1, 1878, p. 137. 



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