Crystalline Limestones of Warren Co., X.J. — Westgate. 371 
nite order. These dioritic rocks occur in great abundance in 
the limestone. They are known to be eruptive, because at 
several localities, where their contact with the limestone can 
be seen, they branch irregularly out into the limestone. In 
one or two cases the diorite is distinctly banded not many 
feet fi-om such eruptive contacts, and were it not that its con- 
tact with the limestone proves it to be eruptive, it might eas- 
ily be mistaken for gneiss. The banding is clearly a second- 
ary structure, and the result of the general metamorphism 
which the region has suffered. 
The relations of the crystalline limestones of Warren county 
to the crystalline limestones in other parts of Xetr Jersey. 
Among the crystalline limestones of New Jersey no localities 
are so well known as those near Franklin, in Sussex county; 
and writers describing the crystalline limestones of the state 
have generally had these prominently in mind as typical, and 
representative of other localities. The} 7 have general!} 7 con- 
sidered all the separate outcrops of these beds in New Jersey 
to be of the same age with the Sussex county rocks. Cook,* 
in describing the crystalline limestones of the state, considers 
together the localities in the southeastern and northwestern 
highlands and places them all in the Azoic (Archaean). Na- 
son,f in describing the Sussex county white limestones, ex- 
tends the belt by isolated outcrops southward to Jenny Jump 
mountain and to Oxford Furnace, making all these outcrops 
of the same age and Cambrian. 
The evidence in favor of this correlation of isolated out- 
crops of crystalline limestone, is mainly lithological, for no 
fossils have been found in any of the crystalline limestones "I 
New Jersey. The reasons for correlating the crystalline lime- 
stones of Jenny Jump mountain with those of Sussex county 
are as follows: (1) Their likeness in lithological character. 
The rocks in both regions are very crystalline, generally 
white or grey limestones, and carry large amounts of acces- 
sory metamorphic minerals. (2) In both areas the limestones 
are cut by similar eruptive rocks — diabase, granite or pegma- 
tite and diorite. (3) In both regions the limestones are more 
or less closely associated with the granitoid gneisses, which 
♦Geology of New Jersey, 1868. 
fGeol. Survey of X. J., Ami. Rept. siat.' Geol. for 1890, pp. 25-27. 
