Invasion to Regional Metamorphism. 11 



tural distinction between this province and the Lanren- 

 tian of Canada appears to rest upon the lesser depth to 

 which erosion has planed and the resulting lesser 

 destruction of the batholithic roofs. 



Relations in New England between Batholithic and Meta- 

 MORPHic Limits. 



Preliminary Statement. 



The regional metamorphism of New England is 

 marked both by a thorough recrystallization of the sedi- 

 ments and a folding and mashing. The intrusive rocks 

 are also involved to a greater or less extent. The gen- 

 erality of this relation, both for this and other regions, 

 has caused them to be linked together in geological theory 

 as direct cause and effect; the deformation of deep- 

 seated rocks being regarded as the cause of their regional 

 metamorphism. This conception developed, however, 

 before the igneous and intrusive nature of the basal 

 gneisses was recognized, and even yet the importance 

 of deep-seated batholithic extension has not been con- 

 sidered in the theory. It is desired here to test this 

 prevailing conception against another which would 

 regard recrystallization as largely and directly related 

 to batholithic heat and emanations, and the .folding and 

 mashing as a related but partly independent process, due 

 to crustal compression, but going on most readily in the 

 weak and recrystallizing roofs of batholithic chambers. 



TJie Fre-Newarh Floor of the Connecticut Triassic. 



To test this question, let the region be considered which 

 lies in Connecticut between the Triassic of the Connect- 

 icut Valley and the dying out of the Appalachian folds 

 in the Hudson Valley. The crust movement at the close 

 of the Newark sedimentation gave a regional tilt of about 

 20° east to the rocks of the Connecticut Valley, and a 

 regional tilt of about 20° west and northwest to the New 

 Jersey area.- Extensive faulting also took place as a part 

 of the movement. The western margin in Connecticut, 

 the eastern in New Jersey, are not in general, however, 

 fault boundaries. They are the two slopes of a geanti- 

 clinal arch upraised at the beginning of the Jurassic 

 period. The fault movements, however, partly neutral- 

 ized the effects of the tilt, so that the actual elevation of 



