﻿Triassic formation of the Connecticut Valley. 347 



cially interesting from the appearance of its posterior ridge in 

 an almost complete oval, the only example in the whole valley 

 where the outcrop of a trap-sheet on the eastern side of its flat, 

 dish-like fold is not cat off by a fault. The escape here is by 

 only a few hundred feet, for the crystalline rocks appear close 

 by. Such an eastern 'outcrop explains 

 the steep slope and convexity of the ridge 

 to the eastward, instead of to the west- 

 ward, as is elsewhere the universal rale; 

 and it is with no small satisfaction that 

 so pronounced an exception to the rule 

 is found to be so completely in accord 

 with the explanation proposed for the 

 structure of the formation : the excep- 

 tional case might have been predicted 

 before observation. Toket Mountain is 

 not separated from Pond Mountain by 

 a fault, but by erosion on a transverse 

 flat arched anticlinal, clearly denned by 

 the dip of the adjacent conformable sand- 

 stones. Toket itself is divided into two 

 unequal lobes by a faint indentation north 

 of its middle; and from an examination 

 of the dip of the accompanying sandstones 

 it becomes clear that this indentation re- 

 sults from a faintly developed transverse 

 anticlinal, of the same kind as that which, 

 when carried farther, has caused the sepa- 

 ration of the Pond and Toket crescents 

 in the present stage of erosion. Indeed, 

 the fate of separation has already over- 

 taken the ridge posterior to Toket, which 

 is cut into two crescents just opposite the 

 indentation between the two lobes of the 

 main mountain. 



There is good reason to think that the wide separation of the 

 Mount Holyoke and Deerfield trap ranges in Massachusetts is 

 due to a similar transverse uplift, but of much greater value: 

 for on this supposition we should expect to find the lowest 

 members of the formation exposed about midway between the 

 strong eastward curves of the ranges ; and surely enough it is 

 in precisely this position that the fundamental crystalline rocks 

 of Mount Warner appear, and they have no other outcrop 

 within the limits of the Triassic formation. The combination 

 of faults and faint, dish-like folds in the way here outlined is 

 therefore not only allowed but demanded by the topography ; 

 and there is good promise that the intricate maze of ridges 



Fig. L— Pond and To- 

 ket Mountains, enlarged 

 from Percival's outline. 

 A transverse section is 

 given for each mountain 

 and a longitudinal section 

 runs through both. 



