NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 7 1 



time interval, whatever it may have been, was probably that involved in 

 a progressive or regressive movement of the conditions which determined 

 the deposits. 



South of Pueblo there is a long, narrow strip along the east front of the 

 Sangre de Cristo range which is marked on the geological map of North 

 America as Permian, continuous with the Permian of the Pecos Valley. As 

 already shown (p. 60), the Triassic extends from the western edge of the 

 Staked Plains well over eastern New Mexico. The Red Beds described by 

 Lee and in part by the author are Triassic, from fossil evidence, and cer- 

 tainly a good part of the beds at Las Vegas Hot Springs are Triassic, as shown 

 by the dinosaur tooth found by the author near the middle of the series just 

 north of the Hot Springs (p. 61). The relation of the beds at Hot Springs to 

 those just south of the Garden of the Gods can be demonstrated only by a 

 careful foot-by-foot traverse and a very tedious search for fossil evidence. 



The author believes that there was a Permo-Carboniferous area of deposi- 

 tion reaching from north-central Texas to the Black Hills and west to the 

 Front Range of the Rocky Mountains. South of the Garden of the Gods the 

 western edge of this area seems to have bent to the east in the latitude of 

 Las Vegas, or the deposits to have become very thin. How far this embay- 

 ment to the east extended is very uncertain; in the valley of the Canadian 

 River the Permo-Carboniferous Red Beds, Quartermaster and Greer, reach 

 at least to the center of the Staked Plains, but do not appear on the western 

 side. South of this they may have extended west to the Guadaloupe Moun- 

 tains, as suggested by Beede.'' 



The material of the Red Beds in the north and west originated in the 

 decay and erosion of igneous and early Paleozoic masses where now lie the 

 Black Hills and Bighorn Mountains and a greater mass extending west 

 from the present Front Ranges of the Rocky Mountains. The southern Red 

 Beds were largely derived from the igneous and early Paleozoic masses in 

 the position of the present Wichita Mountains and Arbuckle Hills. 



Of this great area of similar deposits only a portion of the southern part 

 is well exposed, and of that only a small portion carries vertebrate fossils. 

 But we can at least attempt the delimitation of the whole area and show 

 what lands may have been the source of the sediments and the home of the 

 upland animals. (See plate 4, opp. p. 88.) 



■ Beede, Amer. Jour. Sci., vol. xxx, p. 131, 1910. 



