1882.] 119 [Davis. 



A second theory that was proposed to account for the mono- 

 clinal arrangement, supposed that the present area of the sand- 

 stone strips is but a small part of the surface originally covered 

 by the Triassic deposits. Kerr suggested in 1874 that two paral- 

 lel strips of opposite dip in North Carolina had been once con- 

 nected by a broad intermediate deposit, which after its formation 

 was bulged up into a great arch; the middle parts were worn 

 away and only the marginal remnants with their opposite dips 

 now remain. Russell proposed the same explanation for the 

 opposite dips of the Connecticut — New Jersey areas in 1878. 

 Here again there are many reasons against so wholesale an expla- 

 nation . 1 The vast amount of erosion required ; the absence of 

 outliers that escaped destruction ; the lack of symmetrical oppo- 

 sition of the Connnecticut and New Jersey areas, for the south- 

 ern end of the former is north of the northern end of the latter ; 

 and finally the occurrence of conglomerates again serves us as a 

 test. If the Triassic strata ever reached across the supposed arch, 

 the intermediate area must have all been under water ; and none 

 of its rocks could have furnished sands for the sandstones or peb- 

 bles for the conglomerates ; and yet, along the outcrop-margin 

 (west in Connecticut, east in New Jersey) of the existing strips, 

 there are certain coarse sandstones and conglomerates that seem 

 to be derived from the adjacent granitic hills ; thus showing that 

 they were not submerged, as this theory of anticlinal remnants 

 supposes, but were above water and furnished a share, probably 

 a large share, of the material toward the filling of the Triassic 

 estuaries. It is proper to add, however, that the identification of 

 the source of these conglomerates is not so satisfactorily made out 

 as in the previous case ; more work is wanted here. 



We conclude therefore that the best evidence favors the view 

 that the sandstones were laid down in essentially horizontal layers, 

 in troughs of an area not greatly exceeding the present area of 

 the sandstone strips ; and that the present dip of the strata is 

 owing to a subsequent disturbance. We have next to inquire 

 the character of that disturbance. 



Some observers have been so impressed with the regularity of 

 of the monoclinal dip, and the (supposed) absence of faults and 

 folds, that they have been driven to admitting that a single sim- 

 iSee Dana, Amer. Journ. Sci., xvn, 1879, 328. 



