126 NEW YORK STATE MUSEUM 



colored limestone lying above the Niagara strata, containing generally few 



fossils and among them some forms not unlike those of that in Canada 



West." 



As to the general character of the Guelph Hall concludes : • 



I am therefore induced to believe that this limestone at Racine, the 

 mass at Le Claire and extending thence into Iowa, as well as the Guelph for- 

 mation in Canada and the feeble representation of the same in New York, 

 are really lenticular masses of greater or less extent, which have accumu- 

 lated upon the unequal surface of the ocean bed in a shallow sea during the 

 latter part of the Niagara period. These isolated masses of limestone have 

 close relation with each other while their relation with the Onondaga salt 

 group, though very intimate in the single locality in central New York, 

 becomes less and less conspicuous in a westerly direction. 



A considerable number of Gait fossils are described in this 20th 

 Museum report among the fossils from the Racine beds of Wisconsin. 



Wisconsin. The relations of the Guelph of Wisconsin have been fully 

 treated by T. C. Chamberlin in Geology of Wisconsin, 1877, 2:335 e * se 9- 

 The Niagara group is here divided as follows from top downward : 



At the south ( At the north 



i Guelph beds 1 Guelph beds 



2 Racine beds 2 Racine beds 



' 3 Upper Coral beds 



3 Waukesha beds \ 4 Lower Coral beds 



5 Byron beds 



4 Mayville beds 6 Mayville beds 

 In regard to the Guelph and Racine beds it is said : 



The term Guelph has been applied to the uppermost beds on account 

 of a similarity of fossils to those of the Guelph limestone of Canada, to 

 which the Wisconsin formation is probably equivalent. The recognition of 

 this equivalence is due to Professor Whitfield. 



The Racine beds are the equivalent of what has been known as the 

 Racine limestone, except that the upper portion is now separated as Guelph, 

 and the reefs and associated rocks west of Milwaukee which have been 

 referred to a lower horizon, are included in it. 



The suggestion of Hall that a Guelph and a Niagaran horizon are con- 

 1 N. Y. State Cab. Nat. Hist. 20th An. Rep't. 1867. p. 307. 



