RESUME OF LITEEATUKE. 67 



section is given. Apparently here, as in the Elk Mountains, Stevenson did not see 

 or did not record the light-colored Yule limestone which usually intervenes between 

 the Sawatch quartzite and the Carlioniferous. - 



The Carboniferous section, according to Stevenson, possesses characters which 

 were uniformly observed over all the area examined. Referring to the section on 

 the forks of Eagle River, he remarks: "As exhibited there and elsewhere, the succes- 

 sion seems to consist of, first, a group of sandstones resting on a thick limestone 

 and holding beds of gypsum interstratified with thin limestones; second, resting on 

 No. 1, a gToup of limestones and coarse sandstones; third, above all a great mass of 

 coarse sandstone, in which no beds of limestone were seen." (Page 362.) Applying 

 this to the detailed section of the rocks exposed on the forks of Eagle River (page 368), 

 it appears that the upper division, bed 1 of tlie section, is about 2,500 feet in thick- 

 ness; the middle division, beds 2 to 20, inclusive, 500 feet in thickness; and the lower, 

 beds 21 and 22, about 2,000 feet in thichness. But it must not be supposed that with 

 bed 22 the bottom of the section is reached, for he sa3's (page 370): "With this 

 stratum, which is not more than 200 feet above the bottom limestone, the measured 

 section closes." The "bottom limestone" of this quotation is probably that described 

 on page 362 as the thick limestone upon which the major portion of the section 

 rests. This heavy limestone series must, I think, include the Leadville limestone as 

 one of its members, with possibly the limestones of the Weber formation in its 

 upper portion and the Yule limestone at its base. The three groups of strata over- 

 lying it appear to Ijelong to the Maroon formation. 



Stevenson apparenth' missed the Red Beds altogether in making this section, for 

 (1) he does not recognize any Triassic series in this area, bj^ which name he elsewhere 

 distinguishes the Red Beds; (2) he remarks no discrepancy between this section 

 and the Carboniferous sections of the Crested Butte region, where the Red Beds 

 are apparentlj' wanting; and (3) he compares the upper portion of the section of the 

 Sangre de Cristo Range, in which no strata belonging to the Red Beds are included, 

 with the upper portion of his section on the forks of Eagle River. <* I therefore 

 conclude that Stevenson saw no equivalent of the Wyoming formation in making 

 this section; that if he had he would have referred it to the Triassic; and that the 

 recognizable portions of his section can be referred to the Leadville limestone and the 

 Maroon formation. He probably did not distinguish any beds equivalent to the 

 Weber limestone. 



The whole series of Stevenson's section above the basal limestone appears to 

 belong to the Maroon formation, and is equivalent to the Carboniferous (bed 1 

 to the middle of bed 23) and Permian of Peale's upper Eagle River section, with 

 probably the lower 700 feet of the Permian of the lower Eagle River section. 



I'U.S.Geog. Geol. Surv. W. lOOthMer., Kept., vol. 3,Suppl.,p. 74. 



