PART I. 



GEOLOGY OF THE NORTHERN DIVISION OF THE STATE, EMBRACING THE 

 COUNTIES OF SUSSEX, WARREN, HUNTKRDON, MORRIS, BERGEN, PAS- 

 SAIC, ESSEX, SOMERSET, MERCER, AND PART OF MIDDLESEX. 



Of the Formations embraced n-ithin the Northern Division of the 



State. 



The rocks which constitute the somewhat diversified geology 

 of the northern half of the State are to be classed in three sepa- 

 rate groups, readily distinguishable by their diflerent mineralo- 

 gical characters, the dates of their formation, and the belts of 

 country to which they severally belong. 



Enumerating them in the order of the period of their produc- 

 tion, they are, 



First. A group of primaiy rocks, confined to the Highlands 

 and the vicinity of Trenton. 



Secondly. A group of older secondary strata, confined to the 

 northwestern portions of Sussex and Warren counties, from the 

 base of the Highlands to the Delaware river, and to most of 

 the regular valleys between the primary ridges of the Highlands. 



Thirdly. A group of middle secondary strata, lying in the 

 broad belt of country between the southeastern foot of the High- 

 lands and the boundary connecting Trenton and New Brunswick, 

 including, also, the red shale, red sandstone, and conglomerate 

 rocks, of the Green Pond Mountain. With the above third group 

 are connected the trap rocks, which are confined almost exclusively 

 to the region of the middle secondary formation, just referred to. 

 We arrive at a knowledge of the relative dates of these several 

 formations, from the order in which they severally overlap each 

 other: thus, the lower members of the older secondary or Appa- 

 lachian series, especially the blue limestone, the second from the 



