SUCCESSIVE DEPOSITS IN THE APPALACHIAN REGION 423 



Utica mud phase also extended westward to Cincinnati, where the Fulton 

 shale, from 1 to 26 feet thick and carrying Triarthrus beclci, represents 

 the last of the Trenton-Utica horizon. 



Measurements of the thickness of the Lorraine (Frankfort-Pulaski) 

 beds of the third New York district are obtained by subtracting the esti- 

 mated thickness of the Utica from the total thickness of the shales be- 

 tween the Trenton and the Oswego sandstone. This in Central Square, 

 Oswego County, is 729 feet, leaving 579 feet for the Frankfort and Pu- 

 laski, the lower 100 feet of this being passage beds. At Oswego the total 

 interval is 597 feet, and at Stillwater it is 643 feet, leaving 530 feet for 

 the Frankfort-Pulaski. In Pulaski 500 feet of such shales occur, of 

 which the lower half or less is Utica. In western New York the shales 

 between the Trenton and the Oswego have a thickness of 598 feet at 

 Rochester, where the Trenton is 954 feet, and 630 feet at Buffalo, where 

 the Trenton is 720 feet, and these, as above noted, probably represent 

 largely the Lorraine series of the third district, though of a fades more 

 like that of the Utica. The thickness of the Trenton limestone of the 

 Georgian Bay section from the point where it rests on the gneiss to Col- 

 lingwood, where it passes beneath the "Utica" shale, has been estimated 

 at 900 feet,* though Logan says that "it is not unlikely that the strata 

 may be affected by very gentle undulations, and it would therefore be 

 scarcely safe to state the amount at more than about 750 feet." 35 Even 

 if this latter estimate is the correct one, it must be remembered thai the 

 basal beds of the Trenton are probably absent by overlap, since the lime- 

 stone rests directly on the gneiss. The well known "Utica" beds at Col- 

 lingwood and Windsor are characterized by a great abundance of Asaph us 

 canadensis, together with Triarthrus beclci, Plectambonites sericcus, 

 Rafinesquina alternata, Dalmanella testudinaria, and Rhynchotrema in- 

 crebescens. At Collingwood the rock is a dark, brownish black shale, 

 interstratified with occasional beds of compact, brownish limestone, the 

 shale being very high in bituminous matter. Higher up the beds are 

 "bluish gray argillaceous shales, inclosing beds of calcareous sandstone, 

 sometimes approaching to a limestone ai irregular intervals and of vari- 

 able thickness." 30 Flagstones also occur in (he series. These higher 

 beds contain a typical Lorraine fauna, including Cyrtolites ornatus, 

 ByssdnicTiia radiata, and Modiolopsis modiolaris. Associated with these 

 are graptolites identified as Diplograptus pristis. The whole thickness 



* P. E. Raymond has recently shown (Bull. Geol. Soc. Am., vol. 24, i». lin ili.it th<> 

 highest Trenton strata of western Ontario are younger than the typical Trenton beds of 

 Trenton Falls, N. Y.. which is a direct corroboration of my stratlgraphlc determination, 



M Loc. cit., p. ion. 



38 Logan, p. 211'. 



