98 NEW YORK STATE MUSEUM 



between stable continental areas, whether its margins be elevated or sub- 

 merged, for this conception becomes most pregnant in its relation to the 

 transmission and dispersion of faunas and in the interpretation of 

 bathymetric differences or facies therein. 



It has been the view of several authors that in the progressive deform- 

 ation of the lithosphere primary elevations and plications are circumpolar 

 and concentric and secondary or later plications converge toward these polar 

 regions. We need go no further afield than to cite the Canadian old land 

 or " shield " in what, in terms of geography, is the western hemisphere 

 and the Scandinavian shield in the eastern, as remnants of circumpolar 

 masses now badly shattered ; and the Appalachian mountains, its sister 

 chain the Urals and the Rocky Mountain system, as examples of the 

 meridional converging secondary plications. 



Gaspe presents us with that most singular curve of the Appalachian 

 system in which the course of the axis of plication changes into a sigmoid 

 bending from the south, east and downward like the upper curve of the 

 letter S. It is here that it loses its meridional direction and conforms in 

 curvature to the margin of the old Canadian Archean shield against which 

 it lies. The crystallines and eruptives of the Shickshock mountains, so far 

 as analyzed, are probably to be regarded in part as the effusive incidents in 

 the uplift and plication of the geosynclinal beds ; in eastern Gaspe similar 

 evidences of intrusion are not wanting. The original and approximately 

 east and west depression which bounded the Canadian shield is still 

 expressed by the basin of the lower St Lawrence river which the seas of 

 all later ages since the erosion of the primary uplift have invaded. 



The plicated precarbonic rocks which bound the margin of the 

 Canadian shield seem to owe the present direction of their folds to the 

 course of the original margins of the old land. The history of this 

 northern or oldest part of the Appalachian geosyncline in Gaspe is 

 essentially thus : The plication of the deposits in the great trough began 

 by the upturning of the Cambric slates at the north covering the area 

 beneath and somewhat to the south of the St Lawrence, in folds parallel 



