84 NEW YORK STATE MUSEUM 



a Precambrian Fold System of North America 



Beginning with the Adirondack massif of New York, where the 

 uniform northeast-southwest direction of the folds and foliation 

 first attracted the attention of the writer, we have, as stated before, 

 the unequivocal testimony of Cushing, Kemp, Newland and Smyth ■ 

 of the older authors and that of Ailing, Buddington and Martin 

 of the younger investigators, that the entire massif exhibits strong 

 folding and a general strike of the beds in a northeast-southwest 

 direction. This is especially well brought out in the limestone and 

 graphite belts, and readily recognized on the geologic map of New 

 York in the northwestern section of the massif. 



The " Canadian shield " or protaxis (Laurentia) has become well 

 known through the thorough investigations of Adams, Barlow, 

 Coleman and Miller in the east; through Lawson, Van Hise and others 

 in the west. Adams and Coleman, in the Problems of American 

 Geology (19 15) have vividly described the " epochs of intense folding 

 and metamorphism, accompanied by great batholithic granite 

 intrusions " that marked the end of the Archeozoic and the middle 

 Huronian eras in the east. In both cases, they state, the thrust 

 was from the southeast, resulting in a uniform northeast strike 

 of the folds. Detailed investigations of restricted areas, as those 

 of Cooke (1919) in northern Quebec, verify their statements of the 

 remarkable parallelism of the axes of folding, although there are 

 local diversions from the general direction, as in northern Quebec 

 where it swings more toward an eastern direction and cross folding 

 is developed which sometimes becomes more intense than the general 

 folding. In the eastern part of Ontario, Adams and Barlow (1913) 

 have also found a general N 30 E direction of the planed-down 

 mountain ranges, which direction is also shown by the batholiths 

 and their foliation. 



Along the eastern coast of Labrador a northwest to north-north- 

 west direction of the Precambrian folds appears, but this, according 

 to Adams, is due to Tertiary folding. The cross folds observed 

 by Cooke in northern Quebec may be an expression of the same 

 later diastrophic influence. Along the west coast of Greenland, 

 however, according to the observations of Kornerup (see Suess 

 v. 2, p. 90; v. 3, pt 2, p. 291) the northeast direction prevails again 

 in the Archean gneisses as far as northern Greenland (Suess, v. 

 2, p. 57). Above this are found locally what appear to be Huronian 

 quartzites, quartz-schists etc. (Hovey, 1918). These beds are usually 

 less disturbed than the older formations. In the east of Greenland 

 a north-south direction has been mentioned along some of the 



