258 HENRY B. KUMMEL 
which become more abundant in the upper part of the formation. 
The formation has an estimated thickness of 2,300 feet at Delaware 
Water Gap. It is not known to contain fossils, but its age is fixed 
by its stratigraphic position. 
Green Pond conglomerate——The formation known as the Green 
Pond conglomerate occurs in an isolated belt of Paleozoic rocks which 
extends through the middle of the pre-Cambrian Highlands of New 
Jersey. In constitution it is similar to the Shawangunk conglomerate, 
with which it is correlated, but, inasmuch as it is still an open ques- 
tion whether the Paleozoic strata of the Green Pond Mountain region 
were once continuous with the great mass of Paleozoic sediments 
which le some distance to the northwest, or whether the Green Pond 
region represents a separate basin shut off on the northwest from the 
large Paleozoic sea although communicating with it to the northeast, 
it has seemed best to retain for the present at least both Shawangunk 
and Green Pond as names for these conglomerates in their respective 
fields. 
Longwood — shale-——Immediately above the Green Pond con- 
glomerate, and conformable with it, is a soft, red shale, in which an 
irregular cleavage is usually so highly developed that the bedding 
planes can be determined only with difficulty. The formation is not 
known to contain fossils, but, as it rests directly upon the Green Pond 
conglomerate and is followed by a limestone carrying a Salina fauna, 
it is probably of Salina age. Its stratigraphic position is, in general, 
the same as that of the High Falls formation, but the two may not 
be exactly synchronous. 
FORMATIONS ABOVE THE HIGH FALLS AND LONGWOOD SHALES 
The higher Silurian and the Devonian formations of New Jersey 
occur either in Wallpack Ridge, which les along the northwestern 
border of the state in the upper Delaware Valley, or in the narrow 
belt of Paleozoic rocks in the midst of the Highlands in the Green 
Pond Mountain region. In Wallpack Ridge they aggregate 1,300 
feet or more, while in Green Pond Mountain region they have a 
thickness of about 4,000 feet, of which all but 250 feet are referable 
to beds higher than any of those along Wallpack Ridge. 
