708 On the Former Extent of the Triassic Formation (October, 
assic areas under discussion, must have been composed of sand- 
stone, slate and shale like the escarpments bordering the denuded 
area on either side, but did not include beds of trap, for as we 
have already shown the trap ridges are intrusive sheets derived 
from fissures in the crystalline rocks beneath the regions where 
they occur. 
In my previous essay the statement is made that if fauits do 
not exist in the Triassic beds of New Jersey, that we cannot 
reckon their thickness at less than 25,090 feet. Under the same 
supposition the Triassic formation in Pennsylvania have been cal- 
culated to be 51,500 feet thick. In the notice of my paper which 
appeared in the American Journal of Science} the first three 
objections to.my conclusions are based on the misconception of 
this statement. As to the fourth objection, that the “ northern 
limit of the Connecticut valley sandstone area is north of the 
northern limit of the New Jersey. The New Jersey area cannot, 
therefore, be on the opposite margin of the sandstone region to 
that of the Connecticut valley,” the fact is overlooked that the 
relative position of these two areas has been determined by the 
direction of the axis of upheaval of the central region and by 
the accidents of erosion. Were the Triassic rocks in New Jersey 
entirely removed, those found to the southward, in Pennsylvania 
and Virginia, would still be portions of the western margin of the 
deposit, opposite to that found in the Connecticut valley. 
In objection number five of the review, the sweeping statement 
is made that “ no evidence of such an anticlinal, or of the sup- 
posed amount of erosion, exists excepting this—that the sand- 
stone of the Connecticut valley dip eastward, and that of New 
Jersey, situated wholly to the south of the southern limit of the 
Connecticut valley area, dip northwestward, at the angle stated.” 
The only reply that can be made to this, is simply to refer to the 
remaining lines of evidence converging on the same point. 
It is puzzling to know how “ violent floods of the Connecticut 
river, enlarged for a part of the time by the waters and ice of a 
semi-glacial era” could spread out wedge-shaped masses of coarse 
_ conglomerate along the eastern margin of the Triassic formation, 
the material forming the conglomerate being clearly derived from 
the shores of crystalline rock against which the bases of these 
wedge-shaped masses rest. As we go westward from the old 
1 Amer. Four. Sci., April, 1879, pp. 328-330. 
