308 The American Geologist. November, 1894 
le-ni to shed light upon, but I would suggest that along this 
shore of the ancient sea a long line of sand bars may have 
been built up of the sediments brought in by inflowing 
streams. The channel between these and the mainland may 
have served in later time, when the swampy land had further 
extended itself, as a watercourse, conducting the surplus 
water around the margin to the western outlet. Such a stream 
might finally establish itself and excavate a valle}\ In sup- 
port of this it is worthy of mention that at the present time a 
very slight deflection of the Muskegon river in Newaygo 
county, just before it leaves the Carboniferous area, would 
cause it to continue within the boundary until it reached 
Grand river and the central depression just above Grand 
Rapids through the valley now occupied by the Rouge river. 
The latter heads in Rice lake, within three miles of the Mus- 
kegon and at about the same or a slightly lower level. 
In closing we wish to acknowledge our indebtedness for the 
elevations and general surface configuration, on which this 
paper is based, to a most excellent contour map of the state, 
prepared with much labor by the late Prof. Alexander 
Winchell. 
THE MINERALOGICAL CHARACTERS OF CERTAIN 
NEW JERSEY LIMESTONES. 
By Lewis G. Westgate, Evanston, 111. 
It is the aim of the present paper to describe briefly the 
mineralogical characters of certain of the white or crystalline 
limestones occurring in Warren county, New Jersey. These 
limestones occur along the eastern border of Jenny Jump 
mountain, near its northern end. They are here associated 
with Archaean granitoid gneisses, and are cut by dioritic 
eruptive rocks. 
The rocks under consideration are crystalline limestones. 
In grain they vary between a rather fine-grained crystalline 
limestone, not unlike ordinary marble, and a coarse rock in 
which the faces of the calcite grains are relatively large. In 
color the rock varies from a pure white, through shades of 
gray, to red. Where foreign material is present in abund- 
