EESUME OF LITERATUKE. 127 



characteristic fossils, comprises sandstones, limestones, and dark shales. Their 

 thickness is reported as 1,200 feet, and the series is correlated with the lower sand- 

 stone measures in the Eagle River section. The Triassic beds, having a thickness of 

 1,500 feet, are said to abut against the lower sandstones of the Carboniferous. 



There is nothing to indicate that the older Paleozoics recognized by Cross and 

 Spencer in their Kico Mountains section were seen b_y Stevenson, and his Carbon- 

 iferous, therefore, is more or less completely the equivalent of the Hermosa forma- 

 tion. The character of the Triassic beds is not described, but it is fair to assume 

 that the}" are of the type of the Red Beds elsewhere in Colorado. With this inter- 

 pretation the Triassic would be in a general way the same as the Rico, Dolores, and 

 La Plata formations of the Rico section. Stevenson's measurements are in both 

 cases, it may be mentioned, somewhat less than those more recentl}^ made by Cross 

 and Spencer. Stevenson's correlation of the Hermosa with the lower portion of his 

 Eagle River section is of interest, and that correlation I, too, am disposed to favor. 



The area examined by Endlich in 1874:, called the San Juan district," lies between 

 the one hundred and seventh and the one hundred and eighth degrees of west longi- 

 tude, and between 37- 15' and 38'- 15' north latitude. The Paleozoics in this area are 

 largelj- confined to a more or less crescent-shaped outcrop on the southwest side of a 

 subcircular Algonkian (?) nucleus, the northeastern half being concealed by eruptives. 

 There ai'e also a few small outlying bodies of outcrop, as that at Ouray. 



The arrangement of this report is greatly improved over that of the preceding- 

 year, but we find emplo^'ed the same objectionable method of indicating points of 

 observation by numbered stations which are not systematically described or repre- 

 sented upon a map. 



At only one point, the canyon of Lime Creek, did Endlich observe any beds 

 which he refers to the Sikirian, but in his Devonian are probably" included the older 

 horizons of the Paleozoic section. The Lime Creek exposures are said to consist of 

 white, coarse-grained .sandstones deposited in thick strata, and it was Endlich's now 

 very quaint-seeming opinion that the pre-Devonian beds generally, and these sand- 

 stones in particular, furnished the material for, and by metamorphism were ti'ans- 

 formed into, the quartzites and other Algonkian(?) rocks of this area. Endlich 

 implies that this sandstone underlies and is distinct from his Devonian, but it seems 

 more probable that it is only a local phase of the siliceous lower portion of it (i. e., 

 of the Ignacio quartzite). 



His Devonian along Lime Creek is a light-blue to grayish limestone with 

 abundant fossils, the entire series having a thickness of 1,200 to 1,500 feet. "Above 

 the limestones the Carboniferous beds begin, while they are underlaid probabl}^ for 



aU. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Kept., for 1874, 1876, pp. :81-240. 



