1889. J 
409 
[Davis and Wood. 
gap and is marked 0, like several other stable divides that appear 
to have been adopted after the ancient capture of one stream by 
another ; while the diminished lower part of the stream continued 
to the sea as the Rahway. The Passaic-Plainfield river, (7(7, was 
next captured at (7, its divide between the lower beheaded and the 
upper diverted portions also at last migrating towards the Second 
mountain. But as the distance from the gap of the master stream 
at Paterson increases, its diverting branch, EFJG , has less favor- 
able conditions for capture of the other streams ; hence in the south- 
ern part of the Watchung crescent, there are still several small 
streams draining outward across both trap mountains, whose di- 
vides have not yet been driven to a stable position on Second 
mountain, as has happened in every case farther north. It is corre- 
spondence of this kind that lends color to the hypothesis of super- 
imposition and adjustment that we offer ; but whether it is the color 
of truth or not can hardly be decided at present. The diverted 
course of the upper Passaic was not in the valley, KR , that it now 
follows between the second and third trap ridges, but along the then 
open basin from Great Swamp, (7, northeastward, past J to F; the 
present course of the river being determined by the heavy morainic 
barrier, XXX , stretching from Morristown to Chatham. This com- 
pelled the stream, GJF , to turn back and flow over the courses of 
several streams, GKR , that were presumably independent of one 
another in preglacial time. So with the middle course of the actual 
Passaic, RE ; it is certainly much affected by drift, flowing through 
swamps for long distances, and it cannot be taken as a close indi- 
cator of the maturely adjusted stream by which the crescent was 
drained to the northeast in the Somerville cycle. 
When the trap ridges were disclosed by the wearing away of the 
Cretaceous cover, it maybe that some inequality in their thickness 
or some fractures may have exercised a control in locating some 
of the streams. For the two main sheets we have no indication of 
this, unless it be at the gap in First mountain, where the Rocka- 
way-Rahway river, BB, is supposed to have crossed it. When stand- 
ing on the south end of Orange mountain, as the outer ridge north 
of the gap is locally called, one may look to the south and see that 
there appears to be an imperfect alignment with the southern mem- 
ber, suggesting some dislocation or irregularity in the sheet ; but 
the conclusion is not definite. At the same place, the greater depth 
of the gap in First, than in Second mountain is also apparent and 
calls for explanation ; for it is not easy to see how the beheaded 
