708 G. C. MARTIN TRIASSIC ROCKS OF ALASKA 



ammonites all belong to highly characteristic Upper Triassic genera and 

 point strongly toward a horizon in the Karnic, as does also the pelecypod 

 identified as Halobia cf. superb a Mojsisovics. The latter, according to 

 Stanton, is identical with the species known by that name in the Triassic 

 rocks of California, and is very closely related to, even though it may not 

 be the same as, Halobia superba of the Triassic rocks of Europe. The 

 Chitistone limestone may be regarded as certainly the equivalent of at 

 least part of the Hosselkus limestone of California, and as probably repre- 

 senting in general the lower part of the Hosselkus limestone. The Chiti- 

 stone fauna belongs to the Mediterranean type of Triassic faunas and is 

 believed to be indicative of warm-water conditions. 



On the Yukon Eiver and in the eastern part of the Arctic Mountains 

 (Firth and Canning valleys) are limestones which seem to correspond in 

 general position to the Chitistone limestone. The fauna of these lime- 

 stones is connected with that of the Chitistone limestone by the presence 

 of Halobia cf. superba (see plate 29, figure 2), although it differs from 

 it in the absence of the characteristic ammonite genera Tropites, Juva- 

 vites, and Arcesles, of the corals, arid of such pelecypods as Myoplioria 

 and Pleuromya. It differs also in the abundance of the brachiopods and 

 in the presence of Clionites and several other genera that have not been 

 found in the Chitistone limestone. This fauna may represent the boreal 

 facies of the Karnic, which is elsewhere not well developed in America. 

 The writer regards these beds as probably being approximately synchro- 

 nous with the Chitistone limestone, but as having been deposited in a 

 different basin. 



It is highly probable that the equivalent of the Chitistone limestone is 

 present in the Queen Charlotte Islands, British Columbia (see figure 1). 

 where Dawson has described 30 a massive limestone at least 400 feet thick 

 resting on volcanic rocks and overlain by thin-bedded limestones and 

 flaggy calcareous argillites containing Pseudomonotis sub circular is. The 

 similarity of this section to that of the Chitina Valley is striking and 

 suggestive. It is not possible, however, to establish this correlation defi- 

 nitely on paleontologic evidence, for the published lists 40 of fossils unfor- 

 tunately do not indicate which of the species described by Whiteaves 41 

 were obtained from the massive limestone. A suggestion that these fossils 



33 George M. Dawson : Report on the Queen Charlotte Islands. Geol. Survey of Can- 

 ada. Report of progress for 1S7S-1879, pp. 4SB, 55B, 61B-62B, 63B. 



10 Idem., pp. 49B, 53B. 



41 J. F. Whiteaves : On some fossils from the Triassic rocks of British Columbia. Con- 

 tributions to. Canadian paleontology, vol. 1, pt. ii, No. 3, 18S9, pp. 133-134, 141-142, 148- 



