PRIMARY ROCKS. 



221 



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 outline, 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 

 prevailing 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 the 

 State of New Jersey, 1836. 



