52 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



Under " Lower Silurian system" he placed " (3) Salmon River sand- 

 stone (olive) and green slate, (2) gray Orinoidal limestone, Trenton lime, 

 stone and slate, Mohawk limestone, gray limestone with sparry veins, 

 gray Calcareous sandstone." 



Under the term " Cambrian system (Sedgwick)" he placed " (1) olive 

 sandstone and slate, and varigated sandstone (Potsdam sandstone of 

 Emmons)," and below all these the " Primary." 



In the next report l James Hall gave a somewhat more elaborate list 

 of formations, but distributed them substantially as was done by 

 Conrad. As this classification was only temporary, I will not stop to 

 enumerate it in detail, the final results published in the final reports 

 will be given in the proper place. 



But in the fifth annual Report, Conrad produced a more finished 

 classification, and with slight modifications the order of sequence of 

 deposits and the general relations of the groups to each other are those 

 which appeared in the several final reports; but we do not find the 

 classification into the " divisions of the New York system " in Con- 

 rad's reports. 



We may mention a few points in regard to Conrad's classification of 

 1841 1 . The following names were used : " Tertiary," " Cretaceous Sys- 

 tem," " Oolitic system," " New Red sandstone or Saliferous system," 

 " Carboniferous system," "Old Red sandstone or Devonian system," 

 including the Chemung and Catskill rocks. Then the " Upper Silurian 

 series" included the rocks from the "Oneonta group, No. 26," to the 

 "Black slate, No. 21." The "Middle Silurian series" included from 

 the " Onondaga limestone, No. 20," down to the " Rochester shale, No. 

 10;" the " Lower Silurian series " included from "Pentamerus oblon- 

 gus limestone, No. 9," to the "Potsdam sandstone, No. 1," inclusive. 



Thus we see, that to the end of his work in connection with the sur- 

 vey Conrad's influence was directed toward the correlation of the 

 American classification with that already in use in Great Britain. 



After the annual reports were finished, the several geologists prepared 

 their final reports. We find no evidence that Conrad assisted in their 

 preparation, and in these reports, from the first one published to the 

 last, there is a general symmetry in the classifications, but a neglect 

 of an3 T formal recognition of the classifications already adopted in 

 Murchison's Silurian system, although the authors refer to the corre- 

 lation of some of the New York deposits with recognized horizons in 

 Murchison's Silurian system. A most important feature of the com- 

 pleted reports is the introduction of the " New York system " into 

 geological nomenclature. The New York system was constituted to 

 include the geological deposits from the earliest fossiliferous rocks to 

 the base of the Carboniferous, and we find the four authors disagree- 

 ing in their interpretation of what this system included, and as to the 

 groups into which it was subdivided. 



1 Fourth annual report, 1840. u See Fifth Annual Report, pp. 31-46. 



