400 NEW YORK STATE MUSEUM 



divisions of the Beekmantown beds at East Shoreham can be 

 recognized, as a rule, by their Hthologic characters. 



The section at Chazy village [Brainerd & Seely, 1888^ p. 323] 

 is, for several reasons, to be considered as the type section for the 

 Chazy formation. Not only did Professors Hall and Emmons name 

 the formation after this locality, but it is here also exposed more 

 perfectly than anywhere else in the Champlain valley, with the 

 possible exception of Valcour island, only small portions at the top 

 and bottom being concealed ; and better opportunities for collect- 

 ing the fossils, bed for bed, are offered here than elsewhere. Pro- 

 fessors Brainerd and Seely have carefully mapped the neighborhood 

 of Chazy village and elaborated the section. They found a total 

 thickness of 732 feet of Chazy rocks. These were conveniently 

 divided into a lower group (Group A), a middle one (Group B) 

 and an upper one (Group C). Group A is largely characterized by 

 the presence of Orthis costalis; group B by Maclurea 

 magna, while group C is, at least in some beds, replete with shells 

 of Rhynchonella plena. The three groups have been sub- 

 divided, on Hthologic grounds, into a considerable number of minor 

 divisions. Some of these appear to be recognizable in distant 

 localities ; as the red spot stratum of Ag with Bolboporites 

 americanus, which is also found on Valcour island and on the 

 Valcour shore. The writer has made extensive collections from 

 every stratum of this type locality. These collections, when 

 studied, will it is hoped, afford the means of recognizing distinct 

 fossil horizons and of establishing the sequence and life zones of 

 the Chazy faunules. Since we shall, for the present, refer the 

 cephalopods from the Chazy, here described, to Brainerd and Seely 's 

 subdivisions, we reprint here in full their careful section. 



Measurements at Chac:y in asceiidi)ig order 



GROUP A FEET 



1 Iron gray, fine grained dolomitic limestone, in beds one or 



two feet in thickness, weathering drab with fine yellowish 

 streaks at right angles to plane of bedding; containing 

 Orthis costalis and crinoidal fragments no 



2 Tolerably fine limestone, filled with fragments of crinoids, 



containing Orthis and Strophomena 20 



3 Measures concealed 40 



4 Impure limestone, filled at bottom with Orthis, thin bedded 



when long exposed to weather, the upper six feet abound- 

 ing in crinoidal fragments 30 



5 Fine grained, massive limestone containing S c a 1 i t e s 



a n g u 1 a t u s, Raphistoma and fragments of trilobites. . . 25 



