DOUBLE FLOW OF SECOND MOUNTAIN ■ 201 



river at Little Falls shows no shale in the trap. A well in Caldwell passed 

 through 775 feet of trap without encountering shale ; but a well near East 

 Livingston, 3 miles southwest of Caldwell, gave the following section :* 



Feet 



Soil 5 



Trap rock 90 



Brown sandstone 51 



Trap rock 381 



Total 527 



Over the country between the two crests Darton found red shale frag- 

 ments that he regarded as portions of underlying sediments. 



Klimmelf considered the hypothesis of two successive flows of lava 

 separated by an interbedded layer of sediment, but rejected it because the 

 ridge is single and shows no included sediments at the extremities and at 

 the gorge at Little Palls. Under the seeming necessity of choosing be- 

 tween this hypothesis and that of a curved longitudinal fault, conform- 

 able with the present outcrop. of the trap around the sharply recurved 

 southwestern extremity of Second mountain, both Kiimmel and DartonJ 

 accepted the latter, although no direct evidence of faiilting was found. 



The indirect evidence derived from a study of the width of outcrop and 

 apparent thickness along different section lines may be summarized as 

 follows: On the assumption (1) that there was no deformation in the 

 intervals between the lava flows of the Watchung mountains (nor accom- 

 panying them) ; (2) that sedimentation was uniform throughout the 

 area; (3) that the lava sheets are approximately of uniform thickness; 

 their bases must have been originally parallel. Allowing for Icnown 

 faults, this is still true of First and Second mountains; but from the 

 base of Second mountain to that of Long hill is a distance that varies 

 greatly in different sections, and the apparent differences are greater 

 where the double crests of Second mountain are most marked. This 

 variation is ascribed to faulting, which Darton further assumed to be 

 confined to the areas of the present trap outcrop. As Kiimmel has 

 pointed out, any or all of these various assumptions may be incorrect, 

 and there is no reason for supposing that faulting has been restricted 

 to the areas of the present trap surfaces. 



The above hypothesis has been discussed elsewhere by the writer,§ and 



* Kiimmel : Annual Eeport of the State Geologist of New .Jersey for 1807, p. 12Q. , 

 t Loc. cit., p. 125. 



4 Bull. V. S. Geol. Survey, no. 67, p. 22. 



§ The double crest of Second Watchung mountain, Journal of Geology, vol. xv, pp. 

 39-45. 



