130 NEW YORK STATE MUSEUM 



dividing line between the New York representatives of the Sara- 

 togan (Ozarkic) and the Beekmantown (Canadian). In the Cham- 

 plain region the higher divisions of the Beekmantown occur, but 

 they are utterly lacking in the Mohawk valley and were never de- 

 posited there. The Potsdam sandstone and the passage beds 

 (Theresa formation) are also chiefly confined to the eastern sec- 

 tions, though their thinned edges appear in the easterly Mohawk 

 sections. The Chazy is absent in all sections, the Lowville (or 

 some even younger) limestone resting on the Little Falls, the Tribes 

 Hill or on some later division of the Beekmantown, in the various 

 sections included in the table. 



Stratigraphic positions of the Potsdam, Little Falls and Tribes 



Hill formations 



Saratogan series. Though the Saratogan was defined and is 

 generally accepted as the name of the closing stage of the Cambric 

 in America, it is now practically certain that the deposits of the 

 series in New York are of a later date than are the formations in 

 Missouri, Texas, Oklahoma, Wyoming and elsewhere, that Walcott 

 and others have referred to the Upper Cambric. While there can 

 be no question concerning the essential equivalence of the beds in 

 the latter states, as indicated by stratigraphic position and persist- 

 ence of lithologic and faunal characters, the facts are altogether 

 different in the case of the typical New York Saratogan. Prac- 

 tically the same fauna, the species in many cases being identical, 

 occurs in the middle and more western localities in America in beds 

 corresponding to the sandstone and chert beneath the Jordan sand- 

 stone of the upper Mississippi valley section. These beds are fur- 

 ther distinguished except, in the Great Basin, by the rather abundant 

 presence of glauconitic- or chloritic grains and by the almost con- 

 stant presence of thin limestone conglomerates in their upper parts. 

 Apparently very general sea withdrawal occurred at the close of 

 this Upper Cambric stage. So far as known this Upper Cambric 

 sea is scarcely represented in the Appalachian valley and certainly 

 it did not extend into the middle and northern parts ; but it spread 

 widely in the median areas between the Appalachian and Cordilleran 

 troughs. 



The return of the waters introduced the proposed Ozarkic 

 period of Ulrich. The new sea differed g'reatly from the pre- S 

 ceding Upper Cambric sea in that it failed to cover the Rocky 

 mountain area and in that it submerged the Appalachian and more 



