The Hanging Hills. 27 



greater depth. Thus the overflow of the trap and the erection 

 into ridges were separate events, and may have been wide apart in 

 point of time. There are confessedly exceptions to the rule, in the 

 the case of sheets or layers of trap that were sometimes intruded 

 between successive layers of the sandstone, in which case it came 

 to the surface at an angle corresponding to the dip of the strata 

 and may or may not have overflowed the surface. The one theory 

 makes the the forces that produced the original fractures in the 

 crust and gave vent to the molten matter, the same that built up the 

 ridges; the other makes them independent of each other, even 

 though they may have been of the same general character and of 

 similar origin. It makes West Peak and Cathole and Mount Lam- 

 entation portions of a common trap sheet, merely separated by 

 great faults, and even recognizes subordinate faults along the clefts 

 that partially subdivide South Mountain and others of like config- 

 uration. 



It is too soon to attempt a statement of the comparative evi- 

 dence bearing upon these two theories, and there are problems in- 

 volved that may well delay the settlement of the question for many 

 a day. The statement of two or three points, however, may help 

 to place the matter fairly before the reader. 



I. It has long appeared that that there is a general dip of the 

 sandstone of Connecticut toward the east. It is also in evidence 

 that the trap, in part at least, lies conformably upon the sandstone, 

 and has therefore an easterly dip. One theory would make this 

 dipping of the sandstone the result of an uplift of the whole area 

 along its western border, thus tilting it to the east. And as the 

 dikes or veins of trap have penetrated the strata thus tilted, the pre- 

 sumption is that the eruptions occurred subsequent to the tilting, or 

 possibly contemporaneous with it, the two operations being due to 

 the same general cause. 



The other theory assumes that the whole formation, including the 

 sandstone and the eruptive trap, was completed, or at least well ad- 

 vanced, before the disturbance occurred which produced the ridges; 

 and that the latter are due not to fresh ejections of material, but 

 to faulting of the rocks already in place, the downthrow being on 

 the west side of the fracture, thus producing a dip or inclination 

 to the eastward, but each section of faulted area being independent 

 in the position it assumes, and the dip therefore not necessarily 

 uniform. If the sandstone formed but a thin stratum, this question 

 would be easily decided, for the upthrow of any great fault would 

 expose the entire thickness. But the thickness of the formation is 

 too great for reliable evidence on this point. 



