550 HENRY B. KUMMEL 
materials are well rounded, a fact which in the case of the hard 
quartzites indicates a long period of attrition. 
These conglomerates interbedded with sandstones and shales 
are best exposed in the ‘pebble bluffs” along the Delaware, 
above Milford. The conglomerates form lenticular beds which 
occasionally thin out in the distance of a few rods, to be replaced 
by beds of different texture. The alternation of the beds beto- 
kens shore conditions. 
The heaviest accumulations of the quartzite conglomerate 
underlie the high region stretching northwest from Pittstown 
and south of Pattenburg. This region is known as ‘‘the Bar- 
rens”’ from the nature of the soil, an exceedingly gravelly clay 
resulting from the disintegration of the conglomerate. Less 
massive accumulations occur, also, at other points, chiefly south 
of Clinton, and again four miles north of Peapack, where there 
is an outlier of this rock called Mount Paul. 
Calcareous conglomerates.— Conglomerates composed almost 
entirely of limestone fragments, occur at a number of localities 
along this border. This rock is in appearance almost the exact 
counterpart of the famous ‘‘ Potomac marble” quarried at Point 
of Rocks, Maryland. The limestone pebbles are usually bluish 
or gray, sometimes reddish, set in a red mud matrix, so that the 
rock has a variegated appearance. The average diameter of the 
larger constituents is six or eight inches, but bowlders three feet 
in diameter have been seen. The larger fragments are generally 
rounded, but the majority of the smaller are sharp cornered, or 
at most subangular. Compared with the pebbles in the quartzite 
conglomerate, the limestone pebbles are poorly rounded, a fact of 
some significance in connection with the origin and source of the 
materials, since with equal transportation, the softer limestones 
must have been most worn. In many localities this conglomer- 
ate is so pure a limestone that it is quarried and burnt for lime 
for local use. 
The relations of these conglomerates to the older rocks along 
the border are significant. In some localities the calcareous 
conglomerates adjoin small areas of Paleozoic limestone from 
