lO NEW YORK STATE MUSEUM 



Mohawk region, which is only about lo miles to the north over a 

 continuous outcrop of Frankfort beds.^ 



Darton did not make any special study of the Utica and Frank- 

 fort beds for his ''Geology of the Mohawk Valley" (1893). 



Of great importance for the present work were the investigations 

 of Prosser and Cumings (titles 33, 44). They described a number 

 of sections through the Utica slate and the Frankfort beds (their 

 Hudson River group) and demonstrated the great thickness of 

 these groups in the Amsterdam quadrangle (Utica 950-1260, 

 Frankfort 1200 +)^ Among other things, they made known in 

 the Minaville section a complete transition from the Utica to the 

 Frankfort beds. From the base of the Minaville section a fairly 

 complete section can be obtained along Chuctenunda creek through 

 the Utica down to the Trenton limestone and thus it has been pos- 

 sible for us to study a continuous section from the Trenton to the 

 Frankfort in the lower Mohawk valley. A list of eighteen species is 

 given for the Utica slate at Canajoharie, and a small faunule 

 recorded from the Hudson River shale near the Schenectady pump 

 station, namely, Triarthrus becki, Trinucleus con- 

 centric us, Plectambonites, sericeus, Orthis 

 (Dalmanella) testudinaria, Orbiculoidea 

 sp., Monticulipora (Prasopora) lycoper- 

 d o n , crinoid segments and graptolites. 



A few notes on the Frankfort shale sections along Moyer creek 

 near Frankfort (the type section) and Ferguson creek near Utica 

 were published by Theodore G. White in 1899 and the presence 

 of Triarthrus becki, a small Orthis, a small Orthoceras 

 and graptolites recorded in these sections. 



Purely paleontologic papers on fossils from the Utica slate of 

 the Mohawk valley were published in the decade of 1 890-1900 by 

 Beecher on Triarthrus becki and by Ruedemann on the 

 development of graptolites, and a sessile Conularia. Ruedemann 

 (title 36) also demonstrated that in the Utica shales of the Mohawk 

 valley distinct evidence is found of marine currents following a 

 northeast-southwesterly course. 



1 The terms Trenton limestone, Utica and Frankfort shales are used in this 

 introduction in their old meaning, not in the restricted conception given to 

 them in this paper. 



2 Cumings ( 1900, page 462) measured an actual thickness of the Utica 

 slate of 1 160 feet in the Adebahr hill section. 



