Eruptive Rocks of New Jersey. 113 
two in thickness, before the carbonaceous material was intro- 
uced. Above the amygdaloid is found a metamorphosed shale 
which still retains its bedded structure, and in places presents 
hales 
the bottle is left coated with a solid carbonaceous layer. In 
the rocks, if a fresh supply of oil was furnished from time to 
time by infiltration, the cavities would eventually become com- 
pletely filled with the solid carbonaceous residue. A vesicular 
lava might in this manner be changed to an amygdaloid, the 
Cavities of which would be filled with solid hydrocarbons in- 
stead of quartz, zeolites, ete. 
‘Such, it appears to us, must have been the history of the 
Triassic amygdaloid we have described, the cavities of which 
must at one time have been filled with mineral oil. This is 
but an epitome of what took place on a grand scale at the great 
fissure over 1,400 feet deep, in New Brunswick, which was 
filled with albertite, and in the case of the Grahamite in West 
Virginia, which also occupies an immense fissure. 
Since writing the above, our attention has been called, 
through the kindness of Prof. J. D. Dana, to the fact that Per- 
cival in his report on the geology of Connecticut, published in 
