12 NEW YORK STATE MUSEUM 



These beds were found by Miller (title 65) to be absent on the 

 Remsen quadrangle which adjoins the Little Falls quadrangle to 

 the west. 



The graptolites of the Utica shales and supposed Frankfort beds 

 of the Hudson valley have been fully described by the author in 

 volume 2 of Graptolites of New York (1908). The Utica shale is 

 there characterized as the zone of Glossogr. quadri- 

 mucronatus and Climacograptus typicalis. 

 The presence of subzones and the difference of the faunas in differ- 

 ent districts especially that between the fauna of Holland Patent 

 and the lower Mohawk is pointed out, and the fact brought out 

 (page 36) that the Utica faunules of the Appalachian trough differ 

 from those of the Mohawk valley by the frequent occurrence of 

 Corynoides calicularis 1 which latter only enters 

 the lower Mohawk valley. The transgression of the Utica shale 

 from the northeast is inferred from the faunal evidence and as 

 corollary of this transgression the conclusion drawn (page 49) 

 that the boundary between the Trenton limestone and Utica shale 

 is not a plane of synchrony, and that the areal restriction of the 

 Corynoides to the lower Mohawk valley may be due to the greater 

 age of the eastern Utica beds and its absence farther west, or to 

 the replacing of the shale by the lower Trenton limestone. The 

 Utica of the Hudson valley is thought to be separated by the Magog 

 shales from the lower Trenton Normanskill shale. 



The faunule of the Frankfort shale is described from the sup- 

 posed Frankfort beds at Waterford and Mechanicville. 



In a paper by Grabau on the Physical and Faunal Evolution of 

 North America during Ordovicic, Siluric and early Devonic Time 

 (1909) the relations of the Trenton and Utica are stated as follows: 



The Trenton limestone of America is not a stratigraphic unit, 

 but, as has been repeatedly demonstrated by Ruedemann and noted 

 by many observers, it is the limestone phase of a series which else- 

 where is in part or mostly represented by Utica shale. In the 

 Mohawk valley the dividing line between Utica and Trenton is a 

 line constantly rising to the west, the transition being in some cases 

 abrupt, though probably in most cases it is gradual. Ruedemann 

 has pointed out the progressive increase in thickness westward of 

 the limestone, and corresponding decrease in the shale; the former 

 increasing from 40 feet at Saratoga to 430 feet at Utica, and to 

 954 feet at Rochester, while the latter decreases from 1260 feet to 

 710 feet to probably zero over {he sa me localities. . . . The 



1 Erroneously there referred to C. curtus. 



