UPPER CRETACEOUS 409 



and sandstones with an estimated thickness of 2,000 feet, from which 

 fragmentary specimens of a large Inoceramus and a Desmoceras (?) 

 were obtained. 



Pompeckj, who restudied the old collection of Wosnessenski from 

 near Katmai, reports a specimen of Belemnitella labeled as coming from 

 that place, and on that account infers the presence of Upper Cretaceous 

 there, but this lacks confirmation. 



The Cretaceous beds at Chignik may be directly correlated with those 

 on the Yukon near Nulato, and less certainly with those on the Anak- 

 tuvuk, in northern Alaska, which are the only occurrences of Upper 

 Cretaceous hitherto reported in the territory. 



It is probable that more detailed study will reveal considerable areas 

 of Upper Cretaceous rocks on the Alaska peninsula, but their recogni- 

 tion in rapid reconnaissance is made difficult by the fact that litholog- 

 ically they resemble the Eocene Kenai beds of the same region, which, 

 like the Upper Cretaceous, are coal-bearing and contain fossil plants of 

 similar general types. The relations are further obscured by frequent 

 faults, so that paleontologic evidence is necessary for the identification 

 of the formations in each area; but fortunately both the plants and the 

 animals of the Cretaceous are easily distinguished from those of the 

 Kenai when sufficient collections are obtained. There are doubtless 

 unconformities both below and above the Upper Cretaceous of this region, 

 since all of the Lower Cretaceous is lacking at most localities, and at 

 some places the Kenai rests directly on the Jurassic. 



Resume 



The Mesozoic section of southwest Alaska includes representatives of 

 the Upper Trias, Lower, Middle, and Upper Jurassic, Upper Cretaceous, 

 and probably Lower Cretaceous. 



The Jurassic shows the greatest development, both stratigraphically 

 and faunally, and is probably unequaled in these respects elsewhere on 

 the American continent. The total thickness can not be much less than 

 10,000 feet, and the areas covered by the upper half of the Jurassic are 

 large. 



The faunal type is essentially Russian — that is, boreal, though it 

 differs in the common occurrence of Phylloceras and Lytoceras at sev- 

 eral horizons. The succession of the faunas from the Callovian to the 

 top of the Jurassic is the same as in Russia, but the vertical thickness 

 of beds through which each ranges appears to be very much greater 

 in Alaska. 



The Cretaceous and Triassic rocks so far as now known occur only in 



