128 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



:i considcral)]!' dislaiu'c hv tli(> Silurian sandstone. This was observed, however, only 

 at one point." (Page 211.) 



The section at station 4:8, which appears to be located on the southern boundarj'' 

 of th(> niotaniorphie area, has at its base a white to red and brown quartzite resting 

 immediately upon granite. Next follows a thin stratum of yellow siliceous shale 

 containing narrow intersti'ata of softer shale. This formation is characterized by 

 the presence of well- mar Ivcd pseudomorphs after salt, together with scales and 

 fx'agments of bone of large fishes. Above this the limestones set in. "The entire 

 thickness of the sedimentaries at station iS amounts to about 200 feet, while farther 

 south the limestone alone reaches that figure." The limestone, which is presumably 

 the same in both sections, is evidently the bed to which Cross subsequently has given 

 the name, Ouray limestone. Endlich cites a list of the species found by him in the 

 Ouray limestone. I described and illustrated this fauna characterized b}" the fine 

 species, Camarotc^cliia ondlicJd, in some detail in 1000," and although it was for a 

 time set down as Carboniferous, later and more complete collections vindicate 

 Meek's earh' determination of its ' age as Devonian. The Ouray limestone was 

 succeeded hj an interval of erosion, not of course observed by Endlich, and locallj^, 

 at least, it contains in its upper portion another and quite distinct fauna of Missis- 

 sippian age, whose presence was not known at the time I described the Devonian 

 fauna. Whether the differences in thickness, to which attention is called by Endlich, 

 are due to this post-Mississippian erosion, I am unable to say, but it seems probable 

 that this was partially, at least, the case. If, as one would infer from Endlich's 

 statements, the white limestone, called hj him Silurian, underlies the so-called 

 Devonian, the absence on Lime Creek between the Silurian sandstone and the Ouraj^ 

 limestone of the quartzite and siliceous shale observed at station iS, and of the Silu- 

 rian sandstone at the latter between the granite and the Devonian,- are equally 

 inexjDlicable. It seems more reasonable to suppose that the white sandstone is a 

 local phase of the siliceous beds at the base of the series exposed at station 48, or 

 that it is a new group developed in the thicker section, probablj' at a higher horizon 

 than the quartzite of the latter. The quartzite, both from its lithology and strati- 

 graphic position when compared with other sections, and also from such scantj- fossil 

 evidence as it has yet furnished, is surmised to be of Cambrian age and equivalent to 

 the Sawatch quartzite, while for similar reasons the siliceous shales can be compared 

 with the Parting quartzite, or with that general horizon. The presence of fish 

 remains in this formation rather enforces this hypothesis and brings to mind the fish- 

 bearing Parting beds at Aspen. 



Endlich divides the Carboniferous sediments into two divisions, which he calls 

 the Lower Carboniferous and the Upper. As usual, these terms are to be divorced 



nU. S. Geol. Suiv., Tiventieth Ann. Rept., pt. 2, 1900, pp. 31-63. 



