160 The American Geologist. March, 1894 
the limestone, by the much more coarsely crystalline texture of 
the limestone in immediate contact and by the contact min- 
erals developed. At the south end of the quarry, about one 
hundred feet from the dike, is a bed of non-effervescing lime- 
stone about forty feet thick. Its chemical composition is as 
follows : 
VIII. 
Insoluble 0.07 
Fe 2 3 + A]., O s 1.15 
Ca CO.j 55.28 
Mg CO.j 44.24 
Total 100.74 
There can be no doubt as to the dolomitic nature of this 
rock. 
There is a still more striking fact to be noted in this con- 
nection. On a small knob, 1,980 feet almost directly east of 
bore hole No. 8 (see fig. 1), is an outcrop of granite. At 
this point the white limestone is seen in direct contact with 
the granite. Within fifty feet to the east of this the blue un- 
changed limestone is seen outcropping. Between these two 
points there is thirty feet which is concealed by soil. At 
various points along the strike of the limestone are to be ob- 
served numerous small outcrops of limestone in every degree 
of transition from the unchanged blue to the white. Absolute 
continuity was not visible. To settle the question of contin- 
uity a trench was dug across the strike, exposing a continuous 
series. As was expected, the rock exposure showed a pro- 
gressive transition through almost every shade of color from 
the blue limestone to the coarsely crystalline snowy white. 
The first change was that the blue limestone was broken into 
closely adhering prismatic fragments, showing light irregular 
or mottled streaks with cloudy blue aggregates. Next, the 
limestone showed evidences of strong compression with pres- 
sure planes developed. Along these planes, through which 
the rock split easily, were cloudy carbonaceous bands, with 
the rock a lighter color. Then the bands became more pro- 
nounced with occasional cr} r stalline scales of graphite. Then, 
next, the bands became yet more distinct, and the black earthy 
bands of carbon were changed to bright welts of crystalline 
graphite. The pressure planes were still strongly developed. 
Finally, within six feet of the granite, the pressure planes be- 
