Chapter 5 
MESOZOIC EUIS TORY 
DREASSIC PERIOW 
We have observed that as a result of the Appalachian revolution 
New York State was raised well above sea level and this was its 
condition at the opening of the Triassic period. The total absence 
of any Triassic strata of marine origin makes it quite certain that 
the continent extended farther eastward than it does today and if 
so, the old Paleozoic land mass called Appalachia still existed, 
though probably much diminished in height by this time. The 
absence of marine rocks, however, does not mean that no deposition 
of Triassic sediments occurred within the borders of the State, 
because a remarkable series of nonmarine strata which were ac- 
cumulated along the Atlantic slope are, in part, shown in south- 
eastern New York (Rockland county and Staten island). 
These nonmarine strata are of Upper Triassic age, as told by the 
fossils, and their present distribution and mode of occurrence clearly 
show that they were deposited in a series of long troughlike de- 
pressions whose trend was parallel to that of the main axis of the 
Appalachian range. These troughs lay between the Appalachians 
proper and old Appalachia. The latter also was now partly made 
up of the greatly worn-down Taconics. The facts that these 
troughs are truly downwarps, and that they so perfectly follow the 
trend of the Appalachian folds, make it certain that they were 
formed by a great lateral pressure which was a continuation of the 
Appalachian disturbance. Thus the Appalachian mountains still 
seem to have been growing well into the Triassic period, and while 
the Paleozoic strata were being folded the surface of old Appala- 
chia, including part of the Taconic region, was also more or less 
warped, and the downwarps formed the troughs in which the 
Triassic beds were deposited. One of these troughs extends along 
the Connecticut river through Connecticut and Massachusetts; an- 
other, and the largest, reaches from Rockland county, New York, 
through northern New Jersey, southeastern Pennsylvania, Mary- 
land, and into northern Virginia; while several smaller ones lie in 
Virginia and North Carolina. These depressions were most favor- 
ably situated for rapid accumulation of thick deposits because of 
their position immediately between the two great land masses which 
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