RESUME OF LITERATURE. 69 



overlying 100 feet of shale and sandstone which rests upon 160 feet of limestone. 

 The suggestion conveyed is that the "bottom limestone" which underlies the 

 arenaceous series in the section on the forks of Eagle River, and which I have 

 already inferred to be the basal calcareous member of the generalized Carboniferous 

 section as recognized by Stevenson, corresponds to the limestone forming the base of 

 the section on the West Fork of Taylor River. The character of these limestones is 

 such as to support the belief that they belong to the Leadville limestone. 



In 1876 Endlich was given the White River district for geologic examination 

 and report." "To us," he saj-s, "had been assigned the region lying west of the 

 [White River Indian] agency, bordered on the north hj the White River, on the 

 west by longitude 109"^ 30' west, on the south bj' north latitude ^0°, and joining on 

 the east with the district of the late Mr. Marvine (1873) along a line of about 107° 

 45' west."* This area includes only the western margin of the Grand River Paleozoic 

 region. 



The oldest beds exposed in this district are the Red Beds, or Juratrias. These 

 are said to rest conformablj' upon the Carboniferous, which outcrops extensively in 

 Marvine's district to the east. Endlich's account is verj^ brief and maj^ be condensed 

 into few words. According to him the Trias consists of massive beds of red sand- 

 stone which have a thickness at one point of 2,000 feet and are overlain by a series 

 of gi'aj' shales and marls interstratified with thin beds of sandstone. The latter 

 apparentl3' represent the Gunnison formation of the Crested Butte quadrangle, but 

 the massive white sandstone at the base of the Gunnison is not differentiated here, or, 

 at ail events, is not distinguished liy Endlich. The Triassic itself I am disposed to 

 believe the same as the Lenado Red Beds and the Wyoming formation of the Ten- 

 mile district. The Lenado Triassic is reported as 2,600 feet in thickness, while the 

 latter measures 1,5()0. On the other hand. Endlich states of the Red Beds that "In 

 no manner were they observed to differ particularly from those observed on the 

 eastern slope of the Front Range. Most likely their vertical development is some- 

 what larger here than there, but in all lithological and stratigraphical features they 

 agree closely." The occurrences on the Front Range I have supposed to represent 

 the Wyoming, and possibly, in local sections, part of the Maroon formations. 



ELK MOUNTAIN REGION. 



The only piece of detailed geologic work in the Elk Mountains in which a section 

 is established suitable for use as a basis of comparison with the less complete observa- 

 tions of the several reconnaissance surveys which have visited this region is Folio 

 9 of the Geologic Atlas of the United States.'' 



nU. S. Geol. Geog. Surv. Terr., Tenth Ann, Rept., for 1876, 1878, pp. 61-159. 



filbid., p. 63. 



c U. S. Geol. Surv., Geol. Atlas of the U. S., Anthracite-Crested Butte Folio, Colorado, folio 9, 1894. 



