694 G. C. MARTIN TMASSIC ROCKS OF ALASKA 



Capps as about 1,200 feet. This latter estimate is approximately correct. 

 The type section is in the cliffs on the west side of Nizina River, opposite 

 the mouth of Chitistone River, and is shown in plate 2(3, figure 2. In 

 this view the Chitistone limestone forms the lower vertical cliffs, which 

 are about 2,000 feet high; the Mzina limestone forms the upper more 

 sloping and uneven cliffs, which are partly covered by talus slopes; and 

 the McCarthy formation forms the smooth slopes above the highest cliffs 

 at the left. The Nizina limestone rests on the Chitistone limestone with 

 apparent conformity and is overlain by the McCarthy formation. The 

 latter contact also is apparently conformable in the type section, although 

 there is evidence (see page 711) of an important unconformity at other 

 localities. No fossils have as yet been obtained from the type section of 

 the Mzina limestone. 



In the Kuskulana and Kotsina valleys the Chitistone limestone is over- 

 lain by at least 1,000 or 2,000 feet (possibly several thousand feet) of 

 thin-bedded limestones and shales. 10 These beds doubtless include the 

 equivalent of the Nizina limestone and may include also the lateral 

 equivalent of the upper part of the Chitistone limestone. The fauna of 

 these beds appears to be essentially the same as that of the Chitistone 

 limestone. This may indicate cither that the fossiliferous thin-bedded 

 limestones of the Kuskulana and Kotsina valleys are in part the lateral 

 equivalent of the upper part of the Chitistone limestone, or that the fauna 

 of the Chitistone limestone extends up into the overlying beds. The fol- 

 lowing list represents provisional identifications of 17 small collections of 

 fossils from the supposed Nizina limestone of the Kuskulana and Kotsina 

 valleys. The complex structure of this district (see plate 27) makes it 

 impossible to identify the exact horizons represented by these collections, 

 some of which may possibly have been obtained from thin fault blocks of 

 the Chitistone limestone. The most striking difference between this 

 fauna and that of the Chitistone limestone is in the presence of Cera- 

 iites ( ?) , which was recognized in three collections. This is probably 

 not a true Ceratiies, for that genus is supposed to be characteristic of the 

 Middle Triassic. 



List of fossils from the thin-bedded (Nizina ?) limestone of KusJcnlana and 



Kotsina Valleys 



Orbiculoidea (?) sp. Halobia (?) sp. 



Halobia cf. superba Mojsisovics. Myophoria (?) sp. 



Halobia sp. Pecten (two or three species). 



V. II. Moffit : The Kotsina-Kuskulana district, Alaska. U. S. Geo!. Survey Bull., No. 

 (In preparation.) 



