NEW JERSEY. 
239 
Ignesian limestone areas, as will be explained below. (5) The Mag- 
lian limestone contains frequent masses of black flint or chert. This 
iiever found in the Trenton limestone in New Jersey, except as 
Iber-worn pebbles in the basal conglomerate. 
HUDSON SHALES. 
■The shaly limestones of the Trenton become more clayey and less limy, 
Jl gradually pass into a series of shales, slates, and sandstones. This 
jmation has usually been known as the Hudson shales. The shales 
1 commonly black or dark gray, although green and red beds occa- 
Inally occur. Much of this rock has a marked tendency to split into 
In sheets. This cleavage is not along the bedding planes or layers 
■ which the slate was deposited, but cuts across them at various 
Jkes. It is in virtue of this tendency to split smoothly and regularly 
lo thin layers that some zones of this formation yield excellent roof- 
|r slates; and in some localities, as at Newton, N. J., and Slatington, 
|[, they are largely quarried for this purpose. 
There is considerable difference in the chemical constitution of vari- 
< members of this formation, owing to the variations from shale 
1 slate to sandstone. 
Analyses of Hudson shales and slates, New Jersey. 
1 * 
2 
;i 
4 
5 
6 
ca (Si0 2 ) 
56. 60 
21.00 
5.65 
3.42 
2.30 
.50 
.57 
2.20 
3. 00 
68. 00 
14. 40 
5. 40 
2. 68 
1.51 
.11 
« 77. 53 
\ 10. 10 
3.56 
4.28 
a 76. 22 
13. 05 
2. 67 
.93 
a 79. 36 
• 10.73 
2.07 
2.57 
a 81. 17 
imina (A1 2 3 ) . 
n oxide ( Fe 2 3 ) 
tie (CaO) 
gnesia (MgO) . 
9.80 
1.13 
2.48 
talies (K0 2 , Na 2 0) 
phur (S) 
-bon dioxide (C0 2 ) 
iter 
2.30 
2.70 

. 
a Insoluble. 
Delaware Water (Jap. Geology New Jersey, 1868, p. 136. 
One mile northwest of Coleville. Ibid. 
Near Annandale. Ann. Rept. New Jersey State Geol. for 1900, p. 52. 
Near Lafayette. Ibid., p. 74. 
Newton slate quarry. Ibid., p. 77. 
Near Drakes Pond." Ibid., p. 78. 
GEOL OGIC S Tl! I ■< ' T 1 7,' /•:. 
The general relations of these formations — the Hardyston quartzite, 
e Kittatinny limestone, the Trenton limestone, and the Hudson 
ite — are usually very simple and easily understood. They have 
