484 WILLI A M HERBER T HOBBS 



streams is apparent in their directions, there is no intention 

 thereby to minimize the importance of those studies. The investi- 

 gation of the smaller Newark area of Connecticut, which by con- 

 trast was almost microscopic in its detail, brought out a series of 

 facts which for their interpretation required a totally different 

 theory from the one to which Professor Davis was led by his 

 studies. The two hypotheses have, however, this in common, that 

 the primary cause of the deformation in the Newark rocks is 

 assumed to be the compression of the crust within the area of 

 southern New England by a force of compression, the resultant 

 of which acted in a direction W. N. W. to E. S. E. 



The present writer has been led to the conclusion that the 

 courses of large faults within this general area, if not approxi- 

 mately rectilinear, are in reality zigzags, the elements of which 

 are essentially right lines, examples of this kind being by no 

 means rare in, and, in fact, generally characteristic of, the Pom- 

 peraug Valley. It is not impossible that many of the larger 

 faults described by Professor Davis, if examined in greater 

 detail, might show this peculiarity, and perhaps also fall into 

 the system which has here and elsewhere been elaborated. The 

 numerous broken lines which are so apparent in the boundaries 

 of the trap hills of the Connecticut valley, as represented on the 

 topographic atlas sheets {e.g., Meriden sheet), would seem to 

 favor this view. It is in any case important, as it would seem 

 to the writer, to consider in two stages the dislocations brought 

 about mainly by a lateral compression of a section of the earth's 

 crust, inasmuch as jointing (the production of planes of separa- 

 tion) is in these cases a necessary prerequisite to faulting (dis- 

 placement along planes of separation). The modern views of 

 geologists concerning joint planes produced by the shear from 

 lateral compressive stresses are now sufficiently in accord to 

 assume that vertical block faulting takes place along ready-formed 

 planes of jointmg. In his description of the faulted area of south- 

 ern Norway, Brogger' has been careful to make this distinction. 



' Loc. cit. 



