HAWKINS, LOCEATONG FORMATION OF THE TRIASSIC 147 



Plate VII.) The general trend of the belt is thus northeast and south- 

 west, in harmony with that of the local Triassic in particular, and that 

 of the pre-Triassic rocks and of the Appalachian highlands in general. 



The course of the Lockatong belt is usually marked by a ridge whose 

 long axis corresponds with the strike of the formation. This ridge com- 

 monly has a relief of fifty to a hundred feet or more above the surround- 

 ing Triassic area, which is underlain by the somewhat less resistant rocks 

 of the Stockton and Brunswick series. At Phoenixville, it is traversed by 

 two railroad lines, which cross it by means of open cuts and tunnels. 

 Three railroads cross it between this point and the Delaware River, and 

 each of these has required much excavation. At Byram, Hunterdon Co., 

 N. J., there is a long, persistent series of bluffs flanking the river for a 

 distance of four miles, the cliffs at certain places being exceedingly steep 

 and rugged. Between the Delaware and Princeton the topographic effects 

 are not so pronounced. At Princeton the hard rocks, though not very 

 thick, form a ridge, upon which the town has been built. 



Upon the Lockatong ridge there is a heavy yellow clay soil, which is 

 typical of the formation. In it are seen many irregular, splintery frag- 

 ments of resistant dark-colored shale and argillite. These argillite frag- 

 ments, after a considerable period of exposure to the air, often develop a 

 brown or yellow greasy surface, due to the production of kaolin, which 

 gives rise to the typical sour soils of this belt. These soils, however, are 

 fertile. The high land overlying the Lockatong beds supports an abun- 

 dance of timber, which, throughout much of the area, has been cleared 

 away to make room for prosperous farms. The drainage is active, and 

 most of the larger streams cut directly across the hard rock ridge. 



Stratigraphy 



The portion of the Triassic system exposed in this part of the country, 

 usually referred to as the Newark, is composed of three distinct parts or 

 units, which, named in order from the bottom to the top of the series, 

 are the Stockton, the Lockatong and the Brunswick formations. The 

 Stockton formation is composed of coarse conglomeratic sandstones of 

 light colors, usuall}^ interstratified with red shaly beds. The Lockatong 

 series of dark-colored, fine grained mud-rocks is the one herein described. 

 The Brunswick formation consists of a very thick succession of red shale 

 beds with some portions that are heavy bedded sandstones, and some- 

 times well developed conglomerates. The total thickness of the Triassic 

 rocks in New Jersey is estimated to be 18,000 feet. The larger portion 

 of this thickness is made up of red or reddish brown shaly and sandy 



