326 C. N. FENNER 



RESUME 



We have seen that the series of clastic rocks of the Newark For- 

 mation underlying the First Watchung Trap was deposited as sur- 

 face accumulations in a semi-desert area, mostly under subaerial 

 conditions, in which the wind played an important part. Most of 

 the material from which it was derived is plainly traceable to the 

 old crystallines on the borders of the basin. Either the original floor 

 of the basin on which accumulation began was almost a plain, or 

 accumulation had proceeded to such a degree that minor features of 

 relief had been buried by it, resulting in a surface with only gentle 

 slopes at the period immediately preceding the extrusion of the trap 

 sheet. The usual topographical features of such a surface, in the 

 nature of shallow valleys and stream channels, were present, and 

 we must suppose that the naturally heavier accumulation of detrital 

 material along the bases of the bordering ridges resulted in lines of 

 consequent drainage from the ridges toward a central area of lower- 

 lying ground, which, in the logic of circumstances, would be occupied 

 by a shallow lake or series of lakes. Inasmuch as the drainage on the 

 eastern side of the lakes came from the country lying on the east, 

 we are able to affirm that at least the heavier sediments in the sand- 

 stone series on this side of the lakes had their origin in the eastern 

 hills and to point to this section as the original home of the limestone 

 pebbles in the conglomerate beds. 



Over such a region a flow of lava poured forth, which accumulated 

 in the low-lying areas occupied by the lakes, and spread out over the 

 sloping ground along the border lines. 



When we came to examine the lava itself we saw that it carried in 

 its own mass plain evidences of the structural changes which were 

 produced by the presence of the lakes and of the water-bearing strata 

 beneath. Wliereas beyond the borders of the lakes the lava was of a 

 close, firm texture and showed a condition of quiet and tranquillity 

 during the process of cooling and hardening, over the area of lake 

 bottom there was evidence of violent agitation having affected it 

 during the initial flows, and rapid cooling and the production of much 

 glassy material during succeeding flows, followed still later by the 

 crystallizing effects wrought by heated waters and the production 

 of secondary minerals. 



