198 Account of the Geology, Mineralogy, Scenery, &. 
Between the river Rariton and the Delaware, a rock dif- 
fering materially from the red sandstone of the Passaic, gen- 
erally underlies both mountain and valley ; after approach- 
ing the surface, it extends North to the primitive and passes 
a considerable distance into Pennsylvania ;—it forms the nu- 
cleus of hills of considerable elevation near the Delaware, 
sometimes presenting mural precipices ; the red soil proceed- 
ing from the decomposition of this rock is fertile and well 
adapted for gypsum ; the colour of the rock is red, much 
darkerthan the Newark stone ;—this mineral appears to be 
without grain, to the breath it yields a strong argillaceous | 
odour, and uniformly decomposes when long exposed to air 
and moisture.—I presume it is mostly composed of iron, 
alumine and silex with perhaps a little sulphur ; it may be 
called ferruginous shist—this rock is stratified, splitting 
readily into thin brittle lamine, and is said to rest in some 
places on good freestone. Copper is the only metal 
sought for in this rock ; excavations are now making near 
Brunswick for copper, and very recently new shafts have 
been sunk at an old copper mine near Pluckemin——no ves- 
tiges of copper remain upon the surface at the old mine of | 
Woodbridge. 
-Sandy-hill, an elevation situated between Brunswick and 
Princeton exhibits an alluvial composition, resembling that 
of the hills of Neversink; sand, white and colored clay em- 
bracing beds of ferruginous sand and pudding-stone are the 
minerals that compose the ridge. 
The alluvial borders the greenstone ridge from Bound- 
brook to Springfield, to the West, in general it approaches 
the Rariton within two miles and forms the bed of that river 
a little below Brunswick. Wherever excavations have been 
made in the alluvial tract South of the greenstone ridge, 
strata of sand, gravel and clay are disclosed, but no quar- 
ries or rocks in place. Ochres of good quality are observed 
in many parts of this district, and at Uniontown near Spring- 
- field, compact peat of a superior quality, resting on marl and 
supposed to extend through a morass of five hundred acres; 
bones of the mastodon were discovered a few years since 
in this swamp. I have noticed extensive beds of pipe clay 
in the alluvial tract situated between Woodbridge and Am- 
boy ; itis infusible and is principally alumine, having less 
than twenty per cent of silex in its composition ;—it is white 
