80 CARBONIFEROUS FORMATIONS AND FAUNAS OK COLORADO. 



Pcale's ropt)i't foi' tlic year 1ST3, to which reference haw alreadj' been made, has 

 to do ill pai't with the Elk Mountains, in part with the Front Eange, which I shall 

 consider later on, and with the Park Range." 



Tlie sectit)ns oiven In' Peale can l)e correlated more or less closely with the 

 formations recognized in the Leadville monograph and the Teimiile folio. In fact, 

 they are all located rather north than south of the central portion of the area. Those 

 numbered 9 and IS are the most complete and will best serve to compare with the 

 Leadville section. Section 9, the description of which begins upon page 216 of 

 the Hayden volume, was taken from the Platte River to Trout Creek, about 6 miles 

 north of Fairpla}". Beds 1 to 51, inclusive, Peale refers to the Carboniferous and 

 Permian. They probably all belong to the two formations which are called Weber 

 grits and Upper Coal Measures in the Leadville monograph and Weber grits and 

 Maroon formation in the Tenmile folio. This series consists chiefly of sandstones, 

 with some shalj' beds and a considerable number of 2 and 3 foot limestones. Above 

 these come the Red Beds, which attain here a thickness of 1,500 feet and have "all 

 the characters of the same beds east of the foothills and on Trout Creek west of 

 them." (Page 218.) This series Peale refers to theTriassic?, and it is followed with- 

 out anj' observed unconformity^ b}' the Jurassic, and this bj^ the Dakota Cretaceous. 

 The Triassic, in its character and thickness, invites comparison with the formation 

 which is described in the Tenmile folio as the Wj'-oming formation. It is also 

 similar to the Permian (in part) and Triassic of Peale's section on the Eagle River. 

 Indeed, Peale calls attention to the similarity of the lower portion of his Permian 

 section on Eagle River'' to the upper beds of the series called Permian and Carbon- 

 iferous in the section under discussion. This naturalh^ suggests that the Triassic 

 of the latter corresponds to the Triassic and the upper portion of the Permian, 

 combined, in the former. 



Following Peale's suggestion, all the beds included in his sections Nos. 10, 11, 

 and 12 would belong to the Weber grits and Maroon formation. In the section 

 made from the mouth of Fourmile Creek westward to Horseshoe Mountain (No. 18, 

 p. 229) beds 98 to 78 can with great probabilitj^ be referred to the Sawatch quartzite. 

 Thejr aggregate 150 feet in thickness and consist of quartzites in the lower part and 

 sandstone above. The four beds which come next in the section are limestones and 

 dolomites and probably represent the Yule limestone. It is diiEcult to distinguish 

 the Parting quartzite. Bed 72, representing 50 feet of blue limestone, and bed 68, 

 representing 60 feet of bluish-black limestone, probably belong to the Leadville 

 limestone. If this is so, the interval between beds 77 and 73, inclusive, though repre- 

 senting a thickness of only 100 feet, must stand for the Yule limestone and Parting 



a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Eept., for 1S73, 1874, pp. 212-239. 

 i> U. S. Geol. Geog. Surv. Terr., [Eighth] Ami. Eept., for 1874, 1876, p. 119. 



