710 G. C. MARTIN TRIASSIC ROCKS OF ALASKA 



species from the Middle and Upper Jurassic of England and India, and 

 are less primitive than certain species from the Bhsetic of Europe, and 

 that it does not contain Daonella lommeli, Halobia superba, or Pseudo- 

 monotis subcircularis. They regarded it as representing a Eurasian type 

 of Liassic fauna which is rather closely related to certain unspecified 

 Liassic faunas of Europe and India. 



The writer believes that the reasons stated for the reference of this 

 fauna to the Lower Jurassic are, to say the least, by no means conclusive. 

 The absence of Daonella lommeli Halobia superba, and Pseudomonotis 

 subcircularis does not make its assignment to the Triassic impossible or 

 even improbable. On the other hand, the fact that all of the five recog- 

 nized genera occur abundantly in the Triassic, while two of them (Choris- 

 toceras and Myophoria) are highly characteristic of the Triassic, being 

 authentically known, as far as the writer is aAvare, only in rocks of that 

 system, makes it appear highly probable that this fauna is of Triassic age. 

 The superficial resemblance of the corals, moreover, to those of the Lower 

 Noric reefs of California, Oregon, Alaska, and the Alps suggests that the 

 Sutton fauna may also be of Lower Koric age. In this connection it 

 should be pointed out that the only recognized ammonoid genus, Choris- 

 toceras, in the Sutton fauna occurs also' in association with the Zlambach 

 corals of the Alps. 



Chert horizon. — The cherts that form the lower part of the McCarthy 

 formation of the Chitina Valley are apparently the equivalent of the 

 more massive lower part of the Kamishak chert of the west coast of Cook 

 Inlet and of the cherts that occur in a corresponding stratigraphic posi- 

 tion beneath the Pseudomonotis zone of the Alaska Peninsula. The con- 

 torted cherts of Kenai Peninsula, of Kodiak Island, and of Herring Bay 

 on Admiralty Island are probably also to be assigned to the same position, 

 though on more slender evidence. The occurrence of these cherts below 

 the Pseudomonotis zone and above the Halobia zone in the Chitina Val- 

 ley indicates their general position, but since they contain no fossils they 

 can not be assigned to a definite horizon or be correlated with any rocks 

 of other regions. 



Zone of Pseudomonotis subcircularis. — The highest Upper Triassic 

 rocks known in Alaska are the Upper JSToric Pseudomonotis-bearing beds, 

 which are widely distributed throughout the three major mountain re- 

 gions. This horizon is represented in the Pacific Mountain belt by the 

 McCarthy formation of the Chitina Valley and by strata carrying a simi- 

 lar fauna at the head of White Kiver, at Cooper Pass, in the Upper Su- 

 sitna Valley, on both shores of Cook Inlet, on the Alaska Peninsula, and 

 on Kupreanof Island in southeastern Alaska. In the Eocky Mountain 



