490 CROSS AND HOWE — RED BEDS OF SOUTHWESTERN COLORADO 



Since Knight could find no stratigraphic or fossil evidence for subdi- 

 viding the Red bed section of the Laramie plains, he refers it as a whole 

 to the Permian and compares it particularly with the Permian of Kansas 

 and Oklahoma. While that correlation may be correct, it is manifestly 

 going too far to conclude, with Knight, that, " if adopted, it will deprive 

 the eastern Rocky Mountain region of the term ' Triassic ' and make the 

 basal member of the Mesozoic the Jurassic." 



Accepting the views expressed by Knight concerning the fauna of the 

 Laramie Plains Red beds, it is clear that the section above his lowest 

 fossil-bearing horizon is younger than the Rico formation, but may cor- 

 respond as a whole or in part to the Cutler formation. Nothing indi- 

 cated by Knight suggests correlation of the upper unfossiliferous portion 

 of his section with the Dolores beds. It is to be noted, however, that 

 this upper portion contrasts with the lower, in that it does not grade into 

 limestones northward, but overlies the Permian limestones. The unfos- 

 siliferous portion whose reference to the Permian is still open to possible 

 doubt is 850 feet in thickness, and it does not appear that the section was 

 complete, up to the Jurassic beds. There is, therefore, ample room for 

 a Triassic formation in the Red beds of the Laramie plains. Even if no 

 Triassic beds are now present in the Laramie region, they may have once 

 existed and have been removed by the pre-Jurassic erosion. 



The relation of the Triassic horizon containing vertebrates studied by 

 Brown and Williston to this " Permian " section has not been described. 



" Permian " beds of the Grand and Eagle rivers, Colorado. — In the vicinity 

 of the Triassic horizon observed by Hills, noted above, the upper Paleo- 

 zoic section is of very different character from that near Laramie, but its 

 upper portion was assigned to the Permian by Peale (34) on the basis of 

 a few plants considered by Lesquereux as of that age. The strata so re~ 

 ferred are gypsiferous shales of various colors, yellow, pink and creamy, 

 with some limestone, and are not to be correlated either with the Lar- 

 amie Permian or the Cutler beds on present evidence. These gypsiferous 

 beds are overlain by the Red beds of Peale, assigned to the Triassic, and 

 seemingly this division must include the bone bed of Hills, since the 

 succeeding formation is apparently the normal fresh water Jura. 



Foothill section of the Front range. — The well known Red bed section 

 of the Front Range foothills in Colorado was assigned to the Trias upon 

 no definite evidence, by the geologists of the Hayden Survey, excepting 

 two small areas at Manitou and in Perry (Pleasant) park. A special 

 map of the Manitou region, contained in the annual report for 1874 (18), 

 distinguishes " a peculiar group of strata not observed elsewhere on the 

 eastern slope " as Carboniferous. No good reason for referring these par- 

 ticular strata to the Carboniferous was given by Hayden, and the unique 

 character of these beds thus asserted is not evident to recent observers. 



