372 F. H. Lahee — Metamorphism and Geological Structure. 



especially characteristic of districts in which the dips and the 

 strikes are variable. As illustrating the latter case may be 

 mentioned the area north and northeast of Warren Neck, i. e., 

 the southern nose of the great Swansea syncline. 



On the whole, the attitude of the schistosity in different 

 portions of the Basin is closely related to the attitude of the 

 stratification. 



Conclusions. 



Following are the conclusions arrived at from the study of 

 the Carboniferous rocks of the Basin : 



1. During the period of their deformation, the Carbon- 

 iferous sediments were deeply buried. 



2. On account of the thick cover, or for other reasons, 

 variations in the degree of metamorphism have been directly 

 determined neither by alternating differences of texture nor 

 by relative stratigraphic depth. 



3. The degree of metamorphism is closely related to the 

 kind and intensity of the folding, for (a) metamorphism and 

 compression increase in severity in a southward direction ; (b) 

 the greatest metamorphism occurs in the region where there 

 is greatest regularity of strikes ; (c) contortion of the beds is 

 accompanied by a high degree of metamorphism ; and, (d) the 

 attitude of the schistosity generally bears a close relation to 

 the attitude of the bedding. 



Cambridge, Mass., Feb. 1, 1912. 



(To be concluded.) 



