NOTES ON THE AGE OF THE CONTINENTAL TRIASSIC 

 BEDS IN NORTH AMERICA, WITH REMARKS ON SOME 

 FOSSIL VERTEBRATES 



By F, R. von Huene 



Of the University of Tilbingen, Germany 



For paleontological purposes, it is sometimes unfortunate that 

 the continental Triassic formations of North America can not in 

 all of their parts be properly incorporated in the standard strati- 

 graphic scheme. The standard scheme is, of course, based on marine 

 fossils, and in North America, as in Europe, transition beds between 

 continental and marine strata are missing. This is the cause of the 

 difficulty. In the present paper the author has endeavored to pre- 

 sent a generalized classification of the vertebrate-bearing Triassic 

 beds of North America. 



The Triassic deposits near the Atlantic coast and the Red Beds 

 in the central and western regions have a different aspect. There- 

 fore it will be best to treat them separately. 



I. Central and western regions. — The Triassic Red Beds of these 

 regions are the continuation of and close of a large series beginning 

 at some places with the older Carboniferous, at others with the 

 Permian. Though there is much local variation, the structure and 

 color of the rocks is remarkably uniform. Fossil horizons are rare 

 and it is therefore not easy to compare particular beds that are far 

 distant from one another. The thickness of the Triassic is in gen- 

 eral several hundred meters; the lower limit is not accurately fixed 

 and the upper is sometimes badly defined. Whole divisions may 

 be missing, and often it is not possible to detect such a hiatus by a 

 clearly observed discordance. 



Ward ^ divides his Shinarump beds in northern Arizona (Powell's 

 original Shinarump group less the Moenkopi formation) .530 meters 

 in thickness, into a lower group, the Shinarump conglomerate, con- 

 sisting of 240 meters of coarse, cross-bedded sandstone and varie- 

 gated marls; and an upper group, the Le Roux beds, 240 meters 

 thick and consisting of a lower member of 120 meters of variegated 



1 Ward, L. F., Geology of the Little Colorado Valley, Amer. Joura. Sci., ser. 4, vol. 12, 

 1901, pp. 407-413. 



No. 2644.-PROCEEDINGS U. S. NATIONAL MUSEUM, VOL. 69, ART. 18. 



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