1889.] 
399 
[Davis and Wood. 
determined in the same way : the former is sunk on a long lime- 
stone belt ; the latter on a much shorter one. 
26. Superimposed streams; the North Branch of the Raritan. 
The course of this stream, figure 9, 1 appears to be as distinctly in- 
herited from rock structures that have now disappeared as that of 
the Musconetcong is consequent on structures that still exist. The 
North Branch rises on one of the front masses of the Highlands and 
flows southerly through a deep oblique valley between Mendham 
and Peapack to the Triassic lowlands. On the way at Roxiticus, 
it crosses a belt of limestone that trends south- southwest, reaching 
the border of the Highlands north of Peapack. Now if the North 
Branch had been revived from a course 
dependent on the slope and structure 
of the elevated old Highland pene- 
plain, it must surely have followed 
the relatively soft limestone out to the 
lowlands ; but its indifference to this 
line of easy valley -cutting can be ex- 
plained by the hypothesis of inheri- 
tance of its course from the slope of 
some now extinct overlying beds ; and 
these must have been the Cretaceous. 
The Cretaceous beds must therefore 
be regarded as having once extended 
across the Triassic area and a little 
way over the margin of the crystalline rocks of the Highlands, 
from which they were derived. 
It might be suggested that the present course of the North Branch 
results from the backward gnawing of a “subsequent” stream that 
began as a ravine on the front of the Highland plateau and at last 
captured a back country stream and led it away from the limestone 
valley by the present deep gorge. There are two objections to this 
suggestion. In the first place, streams that are undoubtedly of 
subsequent origin, such as those that flow into the Ramapo from 
the front bluff of the Highlands near the northern border of the 
state, are much shorter than that part of the North Branch from 
1 Fig. 9 represents a portion of the North Branch of the Raritan, where it leaves the 
Highlands, near the southwestern hook of the Watchung crescent. The limestone belt 
that it traverses is shaded by transverse lines. The neighboring towns are P, Peapack; 
R, Roxiticus; M, Mendham. 
