550 LE JOGRNALVOLAGIFOLO GNA 
feet, and with the exception of the gaps at Little Falls and 
Patersonand the low ground along the Pompton river, all of 
which were closed by the ice when the lake existed, this is the 
lowest point in the rim of the basin. The notch is a flat- 
bottomed, steep-sided trench, 60 yards wide at the bottom and 
157 yards wide at the height of the maximum lake level. It is 
cut in hard trap rock, which outcrops at many points on the sides 
and bottom of the trench. Its form is altogether conclusive that 
it was the channel through which flowed a stream of water, whose 
average width was about I50 yards, and whose depth was 
sufficient to give it great velocity. In pre-lacustrine times there 
may have been a col on the site of the notch, but the notch in its 
present form is due largely to erosion by the outflowing current 
of the lake. Through this outlet the drainage of the lake entered 
the North Branch of the Raritan. 
The Millington gorge. —TVhe Passaic river escapes from the area 
of the Great swamp by a deep narrow gorge through Long Hill, 
at Millington. The gorge is 60 to 70 feet deep, very steep 
sided, and, so far as shape is an index, seems to be of very recent 
origin. So young does it appear, that the hypothesis was for a 
time entertained, that it was largely or wholly post-glacial. This 
hypothesis was finally abandoned because of the small amount of 
trap gravel in the valley below the gorge (too little by far to fill 
it), and because of the evidence afforded by the Stanley gorge, as 
to the amount of post-glacial cutting by the Passaic. This 
evidence is cited below. 
The Stanley outlet.— Near Stanley, the Passaic river has cut a 
passage through a drift barrier in post-lacustrine times. The 
amount of post-glacial cutting is here 25 to 30 feet of which 18 
feet is in drift, the remainder in red shale. The passage which 
the river has cut here is much wider, much less steep-sided, and 
less deep than the gorge at Millington. The differences in width 
and slope may well be due to the differences in the hardness of 
the material. The difference in depth between the post-glacial 
cut at Stanley, and the gorge at Millington is most significant. 
All conditions seem to favor erosion at Stanley, as compared 
