THE NEWARK SYSTEM OF NEW JERSEY 547 
forms a broad regular curve, due to the synclinal structure. The 
height of the Hunterdon plateau is due to the wide outcrop, 
curving strike and hardness of these rocks and of the upper layers 
of the Stockton series, all of which have retarded greatly the 
forces of denudation, so that whereas the adjoining softer rocks 
have been reduced to an average elevation of under 200 feet, this 
belt has an elevation of from 500 to 700 feet. 
Along the Lockatong and Wickecheoke creeks, which have 
deeply incised the margin of the plateau, rapids and falls abound. 
Hard dark red flags are interbedded with the black argillites, 
and some of the more pronounced beds can be easily traced for. 
several miles along the curving strike. This was done in so 
many cases at different horizons as to render it almost certain 
that this belt is not traversed by faults of any magnitude. The 
width of outcrop is due to the great thickness and the gentle 
dip. 
Modification of the Lockatong beds.—Important modifications 
were found to occur in this series near the northwestern bound- 
ary. The shales and argillites grade into sandstones, and these 
into coarse conglomerates. Some layers become slightly arkose. 
This change occurs along the strike, and is accomplished within 
six miles or less. Within a mile and one-half along the strike 
from the point where the first pebble-bearing layers were noted, 
the series is composed chiefly of massive conglomerates in which 
the pebbles are frequently six or eight inches in diameter. Since 
not only the Lockatong beds but the next higher series also 
grade into these marginal conglomerates, it will be well to post- 
pone further consideration of them for a brief space. 
The Lockatong beds give rise toa rather heavy wet clay 
soil. The surface is quite thickly strewn with slabs of argillite 
and flagstone, and on the slopes outcrops are generally abun- 
dant. Except in places favorable to the accumulation of the 
soil from higher slopes its depth is generally less than five or six 
feet. 
The Brunswick shale series —I\ have applied this name to the 
great thickness of soft shales and occasional sandstone layers 
