FEATURES OF TRAP EXTRUSIONS IN NEW JERSEY 301 



tory closely adjacent to the trap itself, using in addition only such 

 conclusions as apply to the Newark Formation as a whole. 



At one time, before a detailed study of the region had been made 

 and before the present advance of geology, a submarine origin was 

 assigned to the Newark beds. Later the impossibility of their deposi- 

 tion under such conditions was perceived and it was suggested that 

 they were laid down in an estuary or on the bed of a great river. 

 This theory is still quite commonly held, but many later observers 

 have come to the conclusion that they are almost wholly of continental 

 origin. By this it is meant that they were laid down on land surfaces 

 standing at some elevation above sea-level, on which bodies of stand- 

 ing water, such as lakes or pools, formed but a minor factor so far 

 as sorting of material and deposition of sediments were involved. 

 The conditions must be conceived to have been similar to those now 

 present in the semi-arid inland basins of the West. The chief agencies 

 of transportation and deposition were the general creep of waste 

 material down slopes from disintegrating areas of older rocks in the 

 high lands, the rush of torrential streams, the flow of rivers of more or 

 less permanence, and the sweep of winds. In the lowest portions of 

 the troughs of deposition there would naturally be shallow lakes, unless 

 conditions of extreme aridity prevailed, and I will endeavor to show 

 later that such lakes were probably present in the area under discussion 

 at the time of the overflow of the trap. 



In connection with the theory of a continental origin for these 

 deposits we may quote W. M. Davis on the similar area in Connecti- 

 cut: 



There is little or no direct evidence for marine deposition of the Connecticut 

 Trias. There are no marine fossils yet found. The fish whose imprints occur 

 plentifully in certain occasional strata of black shale are allied to fresh- or brackish- 

 water forms. The prints of land plants and the tracks of land animals argue 

 against the presence of the sea. The tidal currents that have been assumed to 

 be necessary to carry the materials found in some of the coarser layers may be 

 replaced by other agencies that can as well accompHsh this result over the moderate 

 distances here involved. If marine at all, the waters must have been littoral and 

 shallow, and the bottom must have been frequently bared to the sun.^ 



These remarks are equally apphcable to the New Jersey area. 



Let us now examine the clastic deposits immediately underlying 



I Tenth Annual Report U. S. Geological Survey, Part II, p. 32. 



