46 H. B. KUMMEL 



beds the same amount on both sides of the fold. Furthermore, 

 a narrow trap dike was traced uninterruptedly from the back of 

 Sourland Mountain, near Rocktown, to Copper Hill, a distance 

 of five miles. The dike crosses the strike at an angle of forty- 

 five degrees, and the thickness of the shales thus traversed is 

 between 6000 and 7000 feet. There are reasons for believing 

 that the trap was intruded before the tilting and faulting. If 

 these reasons are valid the continuity of the dike is proof that 

 the shales traversed by it are not cut by faults along the strike 

 Since such great thicknesses prevail in these beds, which are only 

 a part of the whole, there is some reason for believing that the 

 entire thickness of the Brunswick shales is near 12,000 feet. 



On the other hand the disparity in the number of known 

 faults in the trap areas and in the sandstone and shale areas 

 indicates that there are probably more faults in the sedimentary 

 beds than have been discovered. The apparent thickness of the 

 Palisades and the two Watchung ridges is from one half to one 

 third greater than the actual thickness, the increase being due to 

 the faults. If the same proportions hold for the Stockton and 

 Brunswick shales the figures given above will be somewhat 

 reduced. The revised estimate, therefore, is as follows : 



Stockton, - - - 2,300 to 3,100 feet. 



Lockatong, - - - 3,50c " 3,600 " 



Brunswick, - 6,000 " 8,000 " 



1 1,800 " 14,700 " 



There is so much uncertainty connected with all measure- 

 ments where there are so many unknown elements that these 

 estimates may be far from correct. It certainly can be claimed 

 for them, however, that they rest upon a much larger basis of 

 fact than many previous figures. 



Of the trap sheets. — The thicknesses of the various trap sheets 

 are not included in the above estimates. 



The Palisades at Jersey City Heights have at least a thick- 

 ness of 364 feet (well-boring), with a total thickness, including 

 the amount removed by erosion, of 700 to 800 feet, according 



