300 C. N. FENNER 



less degraded, so that now their projecting edges form the ridges of the 

 Watchung Mountains. 



In this article it is my purpose to describe certain facts of observa- 

 tion which have been met with in studying this region, especially that 

 portion of it lying in the territory of the First Watchung trap from 

 Paterson southward, and which may throw some additional light upon 

 the relations of the traps and underlying sandstones and upon the 

 general physiographic conditions which existed at the time of their 

 formation. Quarrying operations of recent years have brought cer- 

 tain features to light which are of importance in their bearing upon 

 this subject. 



In order to lay a proper foundation for the facts which are about to 

 be described and to show their significance, it is necessary to enter 

 into some description of the underlying clastic formations. 



THE CLASTICS 



The lowest trap sheet (the First Watchung Trap) rests everywhere 

 upon a series of siliceous stratified rocks. On account of the paucity 

 of fossils contained in these associated strata and the somewhat 

 uncertain position in the paleontological succession of the fossils which 

 have been found, the exact horizon of these rocks is somewhat uncer- 

 tain. They are generally regarded as being of Triassic Age, but it 

 is preferable to use the indefinite term, "the Newark Formation," 

 in referring to them, as is done by the United States Geological Survey, 

 until more exact correlation can be established. In this article it is 

 my intention to consider in detail only those members of the Newark 

 Formation which are found in immediate association with the base 

 of the First Watchung Trap, and to study these chiefly for the purpose 

 of determining the conditions existing at the period when the trap 

 sheet was poured forth. The rocks of the Newark Formation as a 

 whole are of interest in this connection in forming general conclusions 

 with regard to these conditions; but there is the possibility of undis- 

 covered faults running through the series, which might throw alto- 

 gether out of concordance the strata on the two sides of the break, 

 and vitiate the value of the conclusions drawn. Therefore in endeavor- 

 ing to arrive at a proper conception of the conditions immediately 

 preceding the trap-flow, it is better to confine our studies to the terri- 



