98 ANNALS NEW YORK ACADEMY OF SCIENCES 



highlands support the view that the movements of deformation caused 

 the areas of accumulation to assume at times troughlike characteristics. 



The lakes are believed to have been an all-important factor in giving 

 rise to the conditions which resulted in the subsequent alteration of the 

 basalt and the formation of the zeolitic minerals. Indications of their 

 existence beneath the First Watchung flow can be found at Paterson and 

 for a number of miles southward, and again near Plainfield. 



IGNEOUS ACTIVITY 



During some portion of Triassic time, probably the middle or later 

 portion, the general uneasiness which had manifested itself in repeated 

 crustal deformation assumed a somewhat different phase of expression. 

 Numerous outbreaks of igneous activity occurred throughout the entire 

 region from Nova Scotia to North Carolina. There is little indication 

 that these outbursts anywhere assumed the form of centralized volcanic 

 activity, but the fused material appears to have been ejected quietly 

 through fissures whose direction coincides closely with the dominant 

 lines of weakness. "It seems safe to conclude that both the dikes and 

 faults are closely related and were probably, in part at least, contempora- 

 neous." ^ 



The dikes and extruded sheets are found not only in the areas now 

 covered by Triassic sediments, but petrographically similar dikes have 

 been traced through the intervening areas, and the region traversed by 

 them is prolonged southward through South Carolina and Georgia and 

 into Alabama, where they disappear beneath younger strata. The known 

 length is about 1,000 miles. On the borders of the Triassic also, they 

 occur in approximately parallel lines. The various intrusions are re- 

 garded by EusselP as probably referable to the same general period, and 

 the evidence appears to indicate that an area parallel with Appalachian 

 folding, 1,000 miles or more in length and attaining a maximum width 

 of 200 miles, was involved in a history of deformation and igneous injec- 

 tion which presents somewhat similar features throughout. 



The chemical and mineralogical composition of the erupted magmas 

 shows a remarkable uniformity." The general coincidence of the areas 

 of eruption with the areas of deformation, and the extrusion of magmas 

 which may be referred to closely related petrographic types, have un- 

 doubtedly a profound significance, but only the more superficial aspects 

 can be interpreted. 



= I. C. Russell : Op. cit.. p. 77. 



* Op. cit., pp. 71-72. 



'E. S. Dana: Am. Jour. Sci., 3fd ser., vol. 8, p. 300, 1874. 



