EESUME OF LITERATURE. 121 



some of them are delineated as Silurian upon the HajJ^deu Atlas. He states that the 

 sedimentaries maintain a rather unifoi'm character. The oldest of these he seems to 

 refer to the Triassic and Jurassic, though adopting for them the name Mesozoic, 

 which he employs in exclusion of the overlying Cretaceous formations. His Meso- 

 zoic beds, then, include the Fountain and Morrison formations recognized by Cross 

 and bj^ Gilbert, and his Cretaceous opens with what they call the Dakota formation. 



But little space is devoted to the more southern exposures of the Triassic and 

 Jurassic formations, which here, at least, seem to be discriminated, though it is not 

 clear at what point the division is made. ' ' South and southeast of station 78 * * * 

 the shales of a dark red to a brown color seem to increase considerablj' in thickness, 

 * * * while those beds referred to the Jurassic formation seem to decrease in 

 thickness." Combined, their bulk probably exceeds 1,000 feet, though by how 

 much is not told. 



Near the southern limit of the tract grayish limestones and shales of Carbonif- 

 erous age identified b}' fossils are reported, and they are mapped in the Hayden 

 Atlas as Lower Carboniferous. Shortly south of this occurrence the beds which we 

 have been following are concealed bj' the Cretaceous overlap. 



This area which appears under the Lower Carboniferous color in the Hayden 

 Atlas is partially included in the Pueblo quadrangle, and the beds which Endlich 

 discriminated in the manner above described are identified by Gilbert as the Harding- 

 sandstone and Millsap limestone, though apparentl}^ Endlich saw only the latter. 



In his Southeastern district Endlich reports upon the tract along the Front 

 Range, immediateh" south of that included in the San Luis district. ,He describes 

 the Trias as occurring on the southern end of the Wet Mountains, and it is so 

 represented on the Hayden Atlas. 



Endlich's remarks about these strata are somewhat obscure, but apparantly he 

 recognizes two groups, the lower of which, consisting of bright red sandstones, 

 shales, and marls, he calls the Red Beds or Triassic, and the upper consisting 

 of light shales and marls, is called Jurassic. The lower strata have single beds 

 of white or yellowish sandstone mingled with them, and are said to attain a con- 

 siderable thickness. 



Endlich states that these beds are identical with those further north, and 

 expresses surprise that in his area they have not a more general distribution. 



Part of the area which is colored Triassic in the Hayden Atlas falls within the 

 AValsenburg quadrangle, and the beds grouped by Endlich under the title Juratrias 

 are probably the exact equivalent of the Badito and Morrison formations of the 

 Walsenburg Folio, though lithologically Endlich's beds resemble especially the 

 Morrison formation as described and delimited by Hills. 



