100 J. Barrell — Upper Devonian Delta of the 



ing to the main area of Upper Devonian until on the Susque- 

 hanna River it is only eight miles distant. Kiimmel has made 

 thorough studies of this margin as well as of the rocks of tlfe 

 Triassic* and shows that the margin is in large part a fault 

 boundary, the strata dipping northwest against it. Close to 

 the margin are numerous beds of breccia and conglomerates. 

 The breccias are derived from the Cambro-Ordovician lime- 

 stones, but the pebbles of the conglomerates are almost entirely 

 of quartzite. Between the Delaware river and Pompton the 

 Triassic boundary measures 65*5 miles. Of this, 49 - 75 miles 

 now rest against gneisses and granites. In the marginal con- 

 glomerates, however, quartzite conglomerate covers 19*5 miles, 

 limestone conglomerate or breccia 9*75, gneissic conglomerate 

 but 4*00 miles. f The total thickness of the Triassic in New 

 Jersey, Kiimmel^: places at 20,300 feet. This thickness was 

 determined after allowing for reduplication by faults and in 

 spite of an expectation that the thickness was much less. Even 

 if the existence of minor faults should somewhat reduce this 

 figure, it is evident that the group is enormously thick. The 

 conglomerates occur at all horizons, but are extensively devel- 

 oped only within a few miles of the northwestern margin. 



At the time that Dr. Kiimmel made these studies he was 

 inclined to believe that the breccias and conglomerates were 

 the result of wave action, but he has since come to the opinion 

 that the Newark series is of fluviatile origin. The writer also 

 has studied these conglomerates at intervals since 1896. 



Iu order to shorten the discussion and pass more quickly to 

 the bearing on the Upper Devonian problem, the conclusions 

 will be given without extended presentation of the evidence. 

 The relation of the conglomerates to the present margin shows 

 that this was the margin or the vicinity of the margin during 

 sedimentation also. The maintenance of this margin during- 

 such a thick accumulation of sediment indicates that it was a 

 fault boundary then as now. The limestone breccias, holding 

 angular bowlders usually small but ranging up to twelve feet 

 in diameter, are to be interpreted as talus and wash deposits 

 from the immediate vicinity. The waterworn quartzite 

 cobbles show fluviatile transportation for some miles. Their 

 volume indicates that quartzite was the dominant rock over 

 much of northwestern New Jersey during the Newark sedi- 

 mentation. The present juxtaposition of these conglomerates 

 against pre-Cambrian gneiss shows that in the movements of 

 profound fracturing and tilting at the close of Newark time 

 the old fault boundary was utilized ; the northwest side moving 



* Ann. Epts. Geol. Surv. New Jersey for 1896, 1897. 



fH. B. Kiimmel. Ann. Eeport Geol. Surv. N. J. for 1896, pp. 55, 56, 1897. 



% Ann. Rpt. Geol. Surv. N. J. for 1897, p. 59, 1898. 



