TRIASSIC PERIOD 579' 



ates and some shales, attain a thickness between 5,000 and 6,500 feet. 

 Very rarely the track of a dinosaur occurs here also, and a single specimen-, 

 of Stegomus arcuatus has been found. Also see pages 437 and 438. 



In the southern or Eichmond, Deep river, and Dan river area, Ens- 

 sell 224 states that there is much fine grained, black, highly bituminous slate,, 

 with decidedly local bituminous coals, and rarely a zone of black-band iron 

 ore. The coal beds vary in thickness from a few feet to between 13 and 26 

 feet in occasional cases. In this area Emmons found the only so-called: 

 mammal jaws, Dromotherium sylvestre and Microconodon tenuirostris. 

 Of reptiles are present Belodon carolinensis, B. leoii, and the amphibians 

 Pariostegus my ops and Dictyocephalus elegans. Of plants, about 72 spe- 

 cies are recorded, among which is the broad-leafed giant fern Macrotceni- 

 opteris magnifolia. There are 8 species of conifers, 23 of cycads, 6 of 

 Equisetum, and 35 ferns. 



Continental deposits of the Rocky mountains. — The marine Triassic of' 

 California, Oregon, and Nevada early in this period extended into Idaho, 

 and as continental deposits continued thence into eastern Wyoming. Dur- 

 ing the Lower Triassic the Pacific marine waters attained to southeastern 

 Idaho, but apparently there is in this region also much material of a 

 continental nature. Farther to the east all of the Triassic appears to 

 be devoid of marine strata, and, according to Williston, 225 "in both Kan- 

 sas and the Lander region of Wyoming, at least a thousand feet of contin- 

 uous, conformable, uninterrupted, and homogeneous deposits of red sand- 

 stone, deposits utterly barren of all animal or plant remains," lie above 

 the Permic and beneath the Upper Triassic, yielding Keuper types of rep- 

 tiles. These red beds appear to be older than the far more widely dis- 

 tributed Upper Triassic, and all have accumulated under a semi-arid cli- 

 mate, and during a period of widespread crustal movements. The sea was 

 gradually pushed westward, and in the Cordilleran region the area of con- 

 tinental deposits was greatly enlarged, with probable marine connections 

 in British Columbia and southern California. 



In many places in the Upper Triassic deposits occur scattered reptilian 

 remains, making thin zones of bone conglomerates. 226 Here and there 

 are also found fresh-water shells of Unio; likewise wood. In the Petri- 

 fied Forest Park of Arizona occur prostrate tree trunks in abundance, 

 some reaching a length of 120 feet, with a diameter of from 6 to 8 feet. 



Triassic continental deposits are also known in Sonora and Oaxaea, 

 Mexico. In the latter state Wieland informs the writer that the series is 



224 Russell : Bull. no. 85, U. S. Geological Survey, 1892. 



225 Williston : Journal of Geology, vol. 17, 1909, p. 396. 

 228 Cross : Ibidem, 16, 1908. 



