C. R. Keyes — Triassic System, in New Mexico. 425 



section in the Znni region and in the middle of the section in 

 eastern New Mexico would indicate. 



In the Canadian valley, at the eastern border of New Mexico, 

 the sediments of the Triassic system are well represented at 

 the top of the Red Beds section. Farther westward, where the 

 Rio Pecos cuts the Glorietta escarpment, Newberry distin- 

 guished both Triassic and Permian (Cimarron) plant remains. 



Around the entire escarpment of the Llano Estacado, or 

 Staked Plains, in eastern New Mexico and western Texas, 

 embracing an area of over 50,000 square miles, the Triassic 

 beds are more or less well exposed. The New Mexico portion 

 of this belt is 300 miles long. The greater part of the Red 

 Beds section seen in the Canadian and Pecos valleys is of Tri- 

 assic age. Only in the bottom of these valleys is the Carbon- 

 iferous part of the Red Beds found. 



It now seems quite likely that within the boundaries of 

 Kansas none of the Red Beds section can be considered as being 

 of Triassic age. Early Cretaceous erosion, which bevelled off 

 the Red Beds, appears to have removed the Triassic strata alto- 

 gether east of the New Mexico line and north of the Canadian 

 river. The youngest layers of the Early Cretaceous (Comanche 

 series) in overlapping northward on the old, even, erosion-sur- 

 face, now appear to rest, in southern Kansas, on the lower part 

 only of the Red Beds. 



West of the Rio Grande, in north-central New Mexico, along 

 the Chama river, at the locality known as Abiquiu, Newberry 

 and Cope regarded a very thick Triassic section to be repre- 

 sented. Around the Zuni mountains is an important belt of 

 Triassic strata, which according to Dutton are more than 3500 

 feet in thickness. 



As detailed mapping of the region goes on, the beds which 

 have been considered as belonging to the Triassic system will 

 be found to have a very much wider geographic distribution 

 than is at present known, and many new localities will doubt- 

 less be discovered in which these strata are well represented. 



In eastern New Mexico the basal plane of the Triassic appears 

 to be well established at the bottom of a well-marked conglom- 

 eratic sandstone which separates the lower, dark red, clayey 

 Red Beds from the upper, light reddish, sandy portions. At 

 the base of this conglomerate there are abundant evidences of 

 unconformable relationships between the two parts of the 

 section. 



These relationships are well displayed along the northern 

 magnificent escarpment of the Llano Estacado, which forms 

 the south side of the Canadian valley. Drake,* who has traced 

 the formation along the entire length of this great wall, and 



* Texas Geol. Sur., Third Ann. Kept., p. 229, 1892. 



