86 - National Geographic Magazme. 
crescent near the Highlands; Sourland Mountain in the south- 
west ; and Rocky Hill, the southwestern re-appearance of the 
Palisades intrusive trap sheet, lying a little nearer to us. The 
Central plain is also diversified by the Fall-line, a slight but rather 
distinct break in its surface from Trenton (Tr.) on the Delaware 
to a little below New Brunswick (N. B.) on the Raritan. The 
important drainage lines are: the Delaware, forming the western 
boundary of the State, trenching Kittatinny Mountain at the 
Water Gap, cutting a deep transverse valley through the High- 
lands where it receives longitudinal branches, and a shallower 
trench across the Kittatinny lowland and the Central plain-; the 
Raritan, whose north and south branches head in the Highlands, 
while the Millstone joins it from south of the fall-line, cutting 
through Rocky Hill near Princeton (Pr) on the way; and the 
Pequannock-Passaic, rising in the Highlands, gathermg tribu- 
taries in the low basin behind the Watchung ridges, and escaping 
to the front country as a single stream, the Passaic, through 
deep gaps at Patterson. The terminal moraine, marking the 
furthest advance of the second glacial invasion of post-tertiary 
time, is indicated by an irregular dotted band crossing the State, 
from the Narrows of New York Bay, which it defines, on the 
east, passing over Second Mountain by the gap at Summit (S), 
rising midway in the Highlands over Schooley Mountain, and 
traversed by the Delaware at Belvidere (B). 
The Schooley peneplain is indicated by the crest and summit 
altitudes of Kittatinny Mountain, the Highland plateaus and the 
trap ridges. This peneplain once lay low and essentially hori- 
zontal, the practically completed work of the processes of denuda- 
tion acting on a previously high land through a long period of 
time : it is now lifted and tilted, so that its inland portion rises to 
the height of the Highlands, which are its remnants, while its 
seaward portion descends slowly beneath a cover of unconformable 
Cretaceous beds, southeast of the fall-line, and thus hidden sinks 
gently beneath the Atlantic shore. The cover of Cretaceous 
sediments was laid on the southeastern part of the old peneplain 
during a moderate submergence of its seaward portion, before the 
elevation and tilting above mentioned (fig. 2, p. 93). Much of 
the cover has been worn away since the time of elevation (figs. 
3-6, p. 95), which gave opportunity for the opening of deep val- 
leys on the soft limestones and slates among the hard crystalline 
rocks of the Highlands ; and for the production of the broad 
