THE NEWARK SYSTEM OF NEW JERSEY 543 
grade into each other vertically through transition zones several 
hundred feet in thickness, so that it is not always easy to delimit 
them exactly in the field. Moreover, all three members lose to 
a great extent their distinctive characteristics when traced along 
the strike of the northwestern boundary north of Pittstown. With 
these exceptions, however, the beds of each division are en masse 
quite unlike and readily separable from each other. The accom- 
panying map shows their location and the main faults by which 
they are repeated. 
Stockton series—TYhe basal beds of the system are found at 
Trenton where they rest unconformably upon the older crystal- 
line rocks. They consist of (a) coarse, more or less disinte- 
grated arkose conglomerates; (4) yellow, micaceous, feldspathic 
sandstone; (c) brown-red sandstones or freestones, and (ad) 
soft red argillaceous shales. These are interbedded and many 
times repeated, a fact which indicates rapidly changing and 
recurrent conditions of sedimentation. Although there are many 
layers of red shale in this subdivision the characteristic beds are 
the arkose conglomerates and sandstones, the latter of which 
afford valuable building stones. 
In addition to the cross-bedded structure which often prevails 
in the sandstones, ripple-marks, mud-cracks and impressions of 
rain drops occur. The rapid alternation from conglomerates to 
shales and wice versa, the changes in composition in individual 
beds, the cross-bedding, ripple-marks, etc., all indicate very 
clearly that these beds were deposited in shallow water in close 
proximity to the shore. The bulk of the material of which they 
are composed was derived from the crystalline rocks on the south 
and southwest. 
Owing to the tilting and faulting, the Stockton beds out- 
crop in several belts as shown by the map. The most important 
areas are (a) the Trenton area, which extends northeastward to 
Princeton beyond which place it is mostly buried by Cretaceous 
and Jamesburg deposits ; (4) the Hopewell area along the south- 
eastern face of the Sourland plateau, where the upper part of the 
series has been brought to the surface by a fault; (c) the 
