130 



JULES MARCOU ON THE TACONIC OF GEORGIA 



TABLE A. 



SHOWING THE VARIOUS HORIZONS, AND APPROXIMATE GEOLOGICAL AGE OF THE SEVERAL AMERI- 

 CAN GRAPTOLITIC ZONES, BY CHARLES LAPWORTH, 1886. 



GUAPTOLITIC 

 ZON ES. 



Nkw York. 



Canada. 



Systems. 



1st Zone. 



2i]cl Zoue. 



3cl Zone. 



Loriaiiic shale.s (Graptolites). 

 Utica slates (Graptolites). . 



No Lorraine sliales. 



= Utica slates of Lake St. John and Ottawa. 

 ■ Pie-Utica? or shales of Citadel Hill, Quebec. 

 ; (An horizon unknown in New York.) 



Trenton and Black river, of Nor- 



|inanskill, near Albany. 



(Graptolites). 



= Pointe Lfivis or Trenton and Birdscye 

 (shales of Marsouin river, etc.) 



Chazy and Calciferous. 

 (No Graptolites). 



: Quebec group jChazy or Levis, 

 of Locran. | 



ICalciferons or iThree dif- 

 Levis and > ferent 

 Quebec. ) horizons. 



I Cambrian (upper) 



or Pri- 

 > mordial System. 



According to his view, the Quebec group of Logan is divided into an upper part, 

 which he calls Levis or Phyllogra'ptus zone of St. Anne river; and a lower part, or Que- 

 bec and Levis (probably of Calciferous age) with three subdivisions or horizons contain- 

 ing Dictionema and Oldhamia. The upper part is the equivalent of Chazy and belongs 

 to the Ordovician or CainJjro-silurian, or upper Cambrian of Sedgwick. The lower part 

 — "probably of Calciferous age"— belongs to the Upper Cambrian of Lapworth (not 

 Sedgwick) . 



The author recognizes the great difficulty of dividing the Quebec group into two 

 parts, belonging to two different systems, and asks for a "careful study" in order to arrive 

 at "the solution of the great geological enigma of the Quebec group and its puzzling 

 associates." Professor Lapworth says: "The so-called Quebec rocks, of the toAvn of 

 Quebec, . . are not of Quebec age at all. . . They appear to be of greater an- 

 tiquity than the Utiea slates of Lake St. John." In his tabular view, he places them a 

 little below theLTtica, as "pre-Utica," above the Trenton, thus creating a group unknown 

 in New York. lie also says: "Thus it appears at present that we are destitute of any 

 clear evidence that true Utica and Ilud.son river (or Lorraine shales) strata occur any- 

 where along the south side of the St. liawrence from Gaspd to Quebec." A very impor- 

 tant conclusion, differing widely from the classification used until now by the Geological 

 Survey of Canada. 



Table B shows four graptolitic zones instead of three, and unite together northeastern 

 New York, western Vermont and the province of Quebec in Canada. 



