6 TRIASSIC FISHES AND PLANTS. 
kept pace with the accumulation of material; but it was not regular, as we 
find alternations of conglomerate, sandstone, and shale, which were deposited 
in water of different depth. The uniform dip of the Triassic strata in each 
basin and the opposite inclination of those in the Connecticut and the Pali- 
sade areas have been variously explained. One theory proposed by Prof. 
H. D. Rogers’ is that the strata were laid down upon a slope. This theory 
might be true of the coarse material deposited along an inclined shore, but 
could hardly be applicable to the finely laminated shales and limestones 
which accumulated in deep water. 
Another view, advocated by Mr. I. C. Russell? is that the Triassic basins 
of the Connecticut Valley and New Jersey were once connected, and the 
strata were deposited continuously over all the area between them; that 
subsequently the central portion of this area was elevated and the Triassic 
rocks were eroded from it, leaving the two sunken margins occupied by 
beds which rise respectively from the east and west towards the central 
elevated area. Mr. Russell has studied the structure of the Triassic area of 
New Jersey with much care, and in his paper he presents many facts and 
a strong array of arguments in favor of his theory. There are, however, 
two difficulties which suggest themselves and call for further investigation 
of the problem before we can accept this solution. These difficulties are— 
First. Not a trace of Triassic rocks is now anywhere visible in all the 
broad belt between the Hudson River and the Connecticut Valley, and it 
seems scarcely possible that if they once covered this belt to the depth of 
many thousand feet they should have been so completely removed. 
Second. It has been found that on western Long Island, opposite the 
center of the New Jersey Triassic area, the crystalline rocks, which are a 
continuation southward of those lying between the Hudson and the Con- 
necticut, are covered unconformably by Cretaceous strata, with no Trias 
between them. This would indicate that the Trias of the New Jersey basin 
never reached over that portion of the divide. 
Still another theory has been proposed by: Prof. W. M. Davis to ac- 
count oo) the structure of the Triassic beds of the Connecticut Valley. This 
l Fin: al Rover Geology of New fone 1840, pp. 166-171, 
2Annals New York Academy of Sciences, vol. i, p. 220. 
