176 H. p. GUSHING PALEOZOIC IN NORTHWESTERN NEW YORK 



time the rei^orts were written.^- The work was done and the first of the 

 two reports transmitted for publication before the very important paper 

 of TJlrich and Schuchert on "Paleozoic seas and barriers in eastern North 

 America" came to hand.^^ In this paper the same matters were dealt 

 with as details of a much larger theme. The observations set forth in i 

 the present paper necessitate slight modifications in these previously ex- , 

 pressed views. The extent and importance of the unconformity Avhich I 

 is here held to mark the proper line of division between the Cambrian i 

 and Lower Silurian systems indicates uplift of the entire region at the | 

 close of the Cambrian, with the succeeding Beekmantown depression , 

 limited to the Chazy basin. The invasion of the western part of the state '■ 

 by the Stones Eiver waters must be made somewhat earlier than had 

 been thought to be the case, and during Pamelia deposition a land barrier 

 existed between these western waters and those of the Chazy basin. 

 TJlrich has a mass of evidence of other oscillations and correlations, all 

 of which he has most generously placed at my disposal ; but the evidence 

 comes from without the state, is unfamiliar to me, and as it is not essen- 

 tial to the present paper, which is concerned with the positive results of 

 the New York work, it is not touched upon, since it is greatly to be 

 hoped that he will himself be able to publish it in the near future. 



22 Bulletin no. 77, New York State Museum, pp. 51-65, and Bulletin no. 95, pp. 386- 

 394. 



«> Bulletin no. 52, New York State Museum, pp. 633-644. 



I 



