PRIMARY ROCKS. 
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ary passes near Bennington, Vermont, and along 
the western line of Massachusetts, and, crossing the 
Hudson between Peekskill and Newburgh, under the 
name of the Highlands^ it stretches away through a 
part of New-Jersey, forming a wide zone of many 
nearly parallel ridges, with steep sides and very un- 
dulating outhne, or low mountain ranges of moder- 
ate elevation, rarely exceeding 600 feet, to its ter- 
mination in the northern part of Lancaster county, 
Pennsylvania. Upon the New- York State line, 
where this belt of hills is widest, they are limited 
for several miles on the southeast by the Valley of 
the Ramapo, and on the northwest by that of the 
Walkill. The breadth of this zone of hills dimin- 
ishes, therefore, pretty regularly and rapidly in its 
extension towards the Delaware, occupying about 
twenty-three miles upon the New- York line, and 
scarcely eight upon that near the Delaware. The 
prevaihng direction of the strata, which are nearly 
all primary, thoughout the region is northeast by 
north, and southwest by south, while most of the 
principal valleys are composed of blue limestone.* 
Near Trenton we again meet with gneiss rock, 
which, in connexion with mica slate, granite, &c., 
we trace far to the southwest. We have this west- 
ern border of the primary formation across the Sus- 
quehanna, near Columbia, and through Maryland 
and Virginia, keeping parallel with the eastern 
ranges of the Blue Ridge System. The southeast 
edge of the New-England primary is along the north 
shore of Long Island Sound, taking in a small por- 
tion of the west end of Long Island, and passing 
through the city of New- York and Staten Island to 
Perth Amboy. Here these formations are inter- 
rupted by an overlapping of the red shale series in 
New-Jersey, and do not reappear until we find 
them in a mere point, six miles to the northeast of 
* Professor Rogers's Report on the Geological Survey of tho 
State of New- Jersey, 1836. 
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