574 NEW YORK STATE MUSEUM, 



SUMMARY 



The Deep kill section has furnished extensive collections of 

 three different graptolite horizons which, termed after their 

 most characteristic organisms, are: 



c Zone with Diplograptus dentatus and Crypto- 

 graptus a n t en n a r i|u|s 



b Zone with Didymograptus bifidus and P h y 1 1 o- 

 graptus anna 



a Zone with Tetragraptus 



Two of these zones (a and b) are found in contiguous succes- 

 sion, the third is separated by a break in the exposure, but is 

 certainly superjacent on the second zone b. In Great Britain 

 and Scandinavia, all three zones have been observed in the same 

 succession. In Canada, zone a is known from several regions, 

 the most important being the Levis and St John regions. The 

 typical fauna of zone b has become known from the beds near 

 the St Anne river in Canada, and zone c is again present in the 

 Levis beds. The succession of these zones has thus far not been 

 reported as observable in any of these Canadian regions. 



The stratigraphy of the Deep hill section demonstrates that the 

 Main Point Levis beds or those of the Tetragraptus zone are the 

 loivest of the series; that they are followed by the St Anne beds or 

 those of the zone with Didymograptus bifidus etc., and 

 that the Point Levis beds, containing the zone with Diplograp- 

 tus dentatus etc., overlie either directly the St Anne zone or 

 arc separated from it by only an intermediate transitional zone. 



As the Levis beds have been demonstrated to belong to the 

 Beekmantown or Calciferous formation, the two lower of the 

 zones certainly represent part of the graptolite facies of that 

 formation, while the third zone may either belong to this or to 

 the Chazy formation. 



In using the results of a former investigation by the writer 

 of the shales in the vicinity of Albany (N. Y. state mus. Bui. 42) 

 the zones recorded in the first column of the following correla- 

 tion table of the Champlainic or Lower Siluric graptolite shales 

 can be claimed to have been discerned in this region. 



