FENNER, THE WATCHUNG BASALT 97 



the sediments aecumulated. On the one hand, it is contended that they 

 were of wide-spread distribution and that the present more or less de- 

 tached areas are merely remnants of a broad terrane. Others have argued 

 in favor of local basins or troughs of depression, which may have pre- 

 sented analogies to the "graben" of the Ehine or to the Eift Valley of 

 East Africa. To the writer, the intermediate view presented by the New 

 Jersey Survey appears to offer many grounds for favorable consideration. 

 It is as follows :^ 



These conditions are believed to be fully met by the hypothesis of river 

 deposition across a relatively smooth Piedmont plain, fronting the newly up- 

 lifted crystalline foreland, or protaxis, of the Appalachian Mountains, with 

 concurrent synclinal wrinkling and down-faulting of the long basin-like areas 

 in which the present remnants of these rocks have been preserved. . . . 

 Numerous short but vigorous streams brought down the debris of the disin- 

 tegrating and decomposing granites, gneisses and metamorphic sediments of 

 earlier Paleozoic age and deposited them in coalescing alluvial fans across the 

 smoother plain of the crystalline Piedmont. Occasional downward move- 

 ments, of warping or faulting, gave opportunity for local thickening of the 

 deposits along the belts affected. 



According to this conception, the Piedmont plain was of much greater width 

 than the present areas of the Newark strata, and it probably merged into 

 coastal marine and estuarine deposits along the eastern border. As a rule, 

 however, the deposits were probably not very thick except in the elongated 

 areas of progressive or intermittent deformation. Hence, when the whole 

 Piedmont was eventually uplifted, the relatively thin mantle of debris was 

 removed by erosion from the greater part of the region, and only those narrow 

 belts that were protected by downwarping and faulting between adjacent 

 areas of the harder crystalline rocks have been preserved to the present time. 



The writer is inclined to lay especial stress upon the movements of 

 deformation, which appear to have been renewed at intervals through a 

 prolonged period at the same time that deposition was proceeding. They 

 may have been a consequence, in part, of accumulating load, but they 

 were also probably due to deep-seated causes connected with the primary 

 movements. After each movement, the streams were rejuvenated, and the 

 topographic depressions which otherwise would have been eliminated by 

 the constant degradation of the bordering uplands and the accumulation 

 of sediments were accented afresh. 



Within these areas of fluviatile aggradation, certain depressed portions 

 of the surface (in New Jersey at least) were occupied by a series of 

 shallow lakes when the First "Watchung lava-flow occurred.* The existence 

 of these lakes and thejj arrangement along lines parallel to the bordering 



' .1. V. Lewis : Op. cit., p. 107. 



* C. N. Penner : Op. cit., p. 309 ff. 



