* iiraptay 187 
_ Near Newport, on the sea shore, there isa large vein of quartz 
thirty feet wide, cutting through slaty rocks. In this Vicinity are nu- 
merous beds of anthracite from one foot to three feet in thickness, 
and the slate rocks of carbonaceous clay containing them are charged 
with myriads of fossil plants. The intrusion of granite has here 
produced the usual appearances of hardening—vitrification and sco- 
rig, and there are beds of intruded serpentine at Willow Grove, near 
Fort Adams. 
With the geology of this island we were early familiar, and trav- 
ersed it many times with the late Col. Gibbs, in 1807, and we are much 
impressed with the correctness of Dr. Jackson’s views of the conglome- 
rate at Purgatory, two miles east of Newport. The pebbles of hard 
quartzare from an inch toa yard long; they are all ovoidal, and Jie with 
their longest diameters parallel to each other, as if swung around by 
astrong current, like ships at anchor; the surfaces of the pebbles 
are polished as if by long abrasion of water and sand, and they are 
firmly cemented by a finer paste of a similar nature, but apparently 
fused, their surfaces being often covered with an infinity of minute 
crystals of magnetic iron ore, which often also forms a part of the 
cement. We have remarked also that the slaty graywacke in the 
same vicinity, has similar crystals, often distinctly octahedral, and if 
with Dr. Jackson, we attribute- the one to the operation of fire, we 
Must assign the same origin to the other. . There is a rent in this 
conglomerate from eight to ten feet wide, and from thirty six to forty 
four feet deep. This fissure was once occupied by a trap dyke, most 
of which has been washed away by the sea, which, especially in eas- 
terly storms, roars and dashes into this fissure. The power that up- 
hove the rock, has cracked the pebbles accurately in two, like plumbs 
divided by a knife in a pudding.* In Portsmouth, near the north 
end of Rhode Island, there are important strata of anthracite which 
Were once extensively wrought, but the exploration was given up about 
fifteen years ago. The strata were stated to be three in number, and 
varying from two to twelve feet in thickness. 
By Dr. Jackson’s analysis, a clean specimen of this coal gave wa- 
ter and volatile matter 10, carbon 84.5, dark red ashes 5.5. A spe- 
cimen of the rusty coal, gave water and volatile matter 4% carbon 
77.0, dark purple red ashes 16—consisting of silex 7.4, oxide of iron, 
alumina, manganese, and a little lime, 8.0. This is a valuable coal, 
as we have had occasion to know from experience ; and we stated in 
Vol. XI, p. 78, of this Journal, the quantity of inflammable gas 
* The name Purgatory, popularly applied to this fissure, is said to have arisen 
from a lover's leap baving been made across the gulf to please and win a faiy 
maiden ; and the fortunate lover at once declared his transit from — to par- 
