556 HENRY B. KUMMEL 
locally cuts across shales for a total of 1800 feet is certainly well © 
established. The Rocky Hill trap sheet does not follow the 
strike of the shales but crosses them more or less obliquely. 
Where it terminates near Hopewell it is 6000 feet’ or more 
above the base of the Brunswick shales, whereas at Deans sta- 
tion where it disappears beneath the Cretaceous beds, it is 1500 
feet below them. If we are correct in assuming that Rocky 
Hill is a continuation of the Palisades, the sheet descends still 
further, since along the Hudson it is found in beds which cer- 
tainly belong to the Stockton series. A recently dug quarry 
opposite Point Pleasant, Pa., on the Delaware, shows that the 
trap mass there crosses the shales at a steep angle and is also 
intrusive. 
Near Sand Brook village, southwest of Flemington, there is 
a low horseshoe-shaped ridge of trap formed by the outcropping 
edges of a synclinal sheet whose axis plunges northwestward. 
This sheet is extrusive in origin, as is shown by the following 
facts: (a) It is conformable to the enclosing shale; (6) the 
upper surface is everywhere extremely vesicular and only the 
lower portion is dense and full grained; (c) the overlying shale 
is absolutely unaltered within one and two feet of the trap; (@) 
red shale has filled some of the cavities of, the vesicular trap, 
and in one locality a thin layer of finely comminuted trap, glass 
and red shale lies between the normal red shale and the vesicular 
trap. This sheet has not heretofore been described or shown 
upon published maps. 
Metamorphosed shales—Numerous allusions are made in the 
earlier reports to metamorphosed or ‘‘baked”’ shales associated 
with the trap and in some cases found far away from any igneous 
rocks. The black argillites of the Lockatong series have been 
called ‘‘ baked shales”’ by some writers and their hardness and 
blackness ascribed to the contact with the trap, although no 
igneous rocks occur near them. Metamorphosed shales do occur 
in connection with the larger in usive trap masses, but all the 
* These figures are correct just so far as the above given figures of the total thick- 
ness are reliable. 
