THE NEWARK ROCKS 



25 



vails in the sandstones, ripple-marks, mud-cracks and impressions 

 of rain-drops occur. The rapid alternation from conglomerates 

 to shales and vice versa, the changes in composition in individual 

 beds, the cross-bedding, ripple-marks, etc., all indicate very 



Fig. 2.— Subdivisions of the Newark rocks in Western New Jersey. 



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, but where they were found to rest upon 

 Silurian shales, limestones and quartzites, as was the case along 

 the northwestern border north of Flemington, material from these 

 formations has determined their local character. The regions 

 of the Stockton beds form gently rolling lowlands. 



The Lockatong group . — These rocks overlie the Stockton beds 

 conformably. They consist of [a) carbonaceous shales, which 

 split readily along the bedding planes into thin laminae, but have 

 no true slaty cleavage ; (d) hard, massive, black and bluish- 



