RESUME OP LITERA.TUEE. , 93 



Feet. 



5. Limestone, mostly quite siliceous and compact; varies from dove color to black; layers of 



the latter color verj' fetid when struck; weathers in lines and disintegrates readily; almost 

 entirely nonfossiliferous, but near the top saw a few crinoidal plates and some very indis- 

 tinct bryozoans 50 



6. Sandstone, grayish blue in color, fine grained, and entirely converted into quartzite. Below 



this we find an exceedingly dark, hornblendic gneiss. 



The sandstone at the base (No. 6) presumably represents the Sawatch quartzite. 

 Stevenson states that the lunestones, Nos. 3, -i, and 5, are certainly the equivalent of 

 No. 5 of the Bald Peak section, but the dark color of the limestone, together with 

 the character of the meager fauna cited, might suggest that these do not belong to 

 the Yule but to the Leadville limestone, which is known to be present in this region 

 (e. g., at Salida). In the former case the sandstone and clay (1 and 2) would prob- 

 ably be the Parting quartzite; in the latter they would be the earliest beds of the 

 Upper Carboniferous. The Arkansas Canyon is the most southern point along the 

 range at which Silurian beds are cited by Stevenson. 



Carboniferous strata appear to be exposed almost contiuuousl}' along the line of 

 the South Park and Sangre de Cristo ranges, and are mentioned at numerous locali- 

 ties from Quandary Peak to .the divide between Wet Mountain Vallej' and Huerfano 

 Park. The series seems to be twofold, consisting of limestones below and sandstones 

 above. The lower member is a dark limestone of undesignated thickness, and it is 

 usually referred to by Stevenson simpW as "the limestone." Near the Arkansas Can- 

 yon the upper member is described as an enormous mass of reddish and gray sand- 

 stones and shales, not less than 2,500 feet thick, which forms the canyon's walls to 

 its mouth at Pleasant Valley (page 371). At the northern end of the range, in the 

 Leadville region, it is spoken of as "an enormous mass of red and gray sandstones, 

 more or less finely conglomerate, capping the mountains on the main divide, and 

 including several of these thin limestones, two of which are seen in Hamilton Pass." 

 (Page 37rt.) Near its base the upper series is gypsiferous. "In Sangre de Cristo 

 Pass the sandstones are finely exposed, and at one localitj' the limestone is seen with 

 many imperfect fossils, of which Productus semireticulatus is most abundant." 

 (Page 371.) 



The limestone member of the Carboniferous is evidently the Leadville lime- 

 stone, while the sandstone member represents wholly or in part the Weber shale, 

 Weber grits, and Upper Coal Measures, or the Weber and Maroon formations of 

 Emmons's work, and the Arkansas sandstone of Endlich's. In the north, because of 

 the presence of interbedded limestones, and because both the divisions of the 

 Upper Carboniferous which Emmons in the Tenmile folio distinguished as the 

 Weber and Maroon formations, are known to be present, Stevenson probablj^ saw 

 nearly the whole series. Farther south, however, at Arkansas Canyon, he allows a 



