BESUME OF LITERATURE. 57 



Section at Battle Monntaln, Eagle County. 



Feet. 

 Cambrian white quartzite 125 



Fiiie-grained sandstone 100 



Silurian white quartzite 5 



Conglomerate quartzite. 8 



Blue dolomitic limestone 250 



Black siliceous limestone 300 



Carboniferous limestone 1, 000 



Lead ville quartz-porphyry 200 



Over the ridge 1,000 feet and more of Weljer grits, sandstones, shales, and 

 quartzites were found. 



Pi'obabl_y the four lower members of the section, aggregating 238 feet, should 

 be considered as rej)resenting the Sawatch quartzite. This formation is 160 to 200 

 feet thick in the Tenmile district, and in the Aspen district from 100 feet in the 

 southern part to 200 feet or less in the northern part, so that Tilden's measurement 

 is not excessive. The next two divisions, amounting to 550 feet, have the position and 

 character of the Leadville limestone. If they be taken to represent the Leadville, how- 

 ever, no equivalent of the Yule and the Parting cjuartzite can be found. It is clear 

 from Emmons's remarks that these formations are not normal at this locality. If a 

 portion of the blue dolomitic limestone belongs to the Yule, the Parting quartzite 

 would still be missing. Tilden seems to suggest that the third member of the section, 

 which he designates the Silurian quartzite, is the Parting formation. If this is 

 indeed the case, the Yule limestone as such is absent. The next bed, consisting of 

 1,000 feet of limestone, would appear to represent the Weber formation of the Aspen 

 district and the Weber shale of the Tenmile district. The Leadville limestone and 

 the Weber here are comparable in thickness, and seemingly in character, with their 

 equivalents in the Aspen" and Peale's Eagle River sections. In the Tenmile district 

 these formations have a thickness of but 200 and 300 feet, respectively. In the 

 Crested Butte quadrangle they measure 400 to 525 feet and 100 to 660 feet, respec- 

 tively. At Aspen, howevei-, they attain a thickness, the one of 350 feet and the 

 other of 1,000 feet, while on Eagle River their combined thickness is somewhere 

 near 1,600 feet. 



The area assigned to Marvine in 1873* is a rectangle included between parallels 

 39° 30' and 40° 20' north latitude and meridians 104"^ 45' and 106'^ 30' west longitude. 

 In the southwestern corner of this area is the most eastern portion of the Grand 

 River Carboniferous area, but apparently Marvine was not able to push his work 

 into this tract, for I do not find it described in his report. In the year following 

 his surve3' was extended to the area west of that which he examined in 1873. This 

 territory Haj'den described in the following words:'' "The main portion is bordered 



«Not in thickness in the case of the Aspen section, however. 



bV. S. Geol. Geog, Surv. Terr., [Seventh] Ann. Kept, for 1873, 1874, pp. 83-192. 



c U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Kept., for 1874, 1876, p. 2. 



