RECAPITULATION OF PALEOZOIC FORMATIONS. 181 



There can be no reasonable doubt of the absence of these strata in Lee's section, but 

 as we have just seen, rej)uted Lower Carboniferous is mapped by Endlich about 

 Trinchera Peak, while on the west side of the range, almost opposite where Lee's 

 section was made, E. C. and P. H. Van Diest found the Sawatch quartzite and the 

 Yule limestone in an area where the Arkansas sandstone is represented in the Hayden 

 atlas. Lee cites Coal Measui'e fossils from several horizons near the base of the 

 Arkansas sandstone, and fossils more or less diagnostic of the same age were reported 

 bj' Hayden, Rutfner, Endlich, and Stev^enson, the earliest as far back as 1869. The 

 general resemblance to the Maroon formation, as it appears at other points in Colo- 

 rado, of the series to which Endlich applied the name Arkansas sandstone in the 

 Sangre de Cristo Mountains is apparent. It is to be remarked that in spite of the 

 uniformity in general characteristics and the variability in details which this forma- 

 tion shows it seems generally divisible into two more or less equal portions. This 

 has been done by Stevenson, as we have just seen, in the Crested Butte quadrangle 

 and in the Tenmile and Leadville districts. Frequently the upper division seems to 

 be characterized by a deeper red color than the lower, though when the lower has 

 but little of a reddish tinge the upper does not show the same brownish red that 

 appears where the lower is darker. The occurrence of coarse conglomerates derived 

 from the Archean is somewhat variable. Stevenson cites conglomerates of this 

 character and origin from the upper division in the Sangre de Cristo Range and 

 from the top of the lower division on the forks of Eagle River. In the Crested Butte 

 district sediments of this tj'pe appear in the upper half of the Maroon, while in the 

 Tenmile section they occur in the Wyoming sandstone. This circumstance suggests 

 a consideration of the possibility of the Wyoming sandstone and its correlates 

 being only local variations of the same large series. The great variability in detail, 

 especialh' in color, of this series at different points would lend probability to such 

 a supposition, and the fact that where the thickest sections of the Maroon occur 

 (Crested Butte (juadrangle and Sangre de Cristo Range) sediments of the W3foming 

 type are not found. On the other hand, the ver\' general change of tint to beds dis- 

 tinguished by distinctly brick-red color, the overlap of these beds upon the Archean 

 (as along the Front Range and in the Dolores Valley), and the marked faunal break 

 which sometimes occurs (as in the San Juan region) between the brick-red series and 

 the underlying Carboniferous strata, seem to indicate that this is a distinct group. 

 Stevenson's comparison of the upper series of the Sangre de Cristo Range with the 

 upper portion of the Eagle River series is interesting, because the Eagle River beds 

 appear to belong to the Maroon conglomerate and to occur below the horizon of the 

 W^^oming sandstone. 



Except for rare patches of older Paleozoic beds and the occasional overlapping 

 of sediments of later deposition, the strata lying next to the granite and almost con- 



