s 2.) 
) e wardly, bearing before it immense masses of debris, and depositing 
them far to the south of their original places. Around the city of 
4 
185 
Providence and on the island of Rhode Island are found bowlders of 
porphyritic iron ore, that have been transported many miles from their 
native bed in the iron mine hill in Cumberland ; the bowlders near 
Providence being two or three feet in diameter, decreasing in size as 
we go south, until they are not larger than a cannon ball. “The width 
of the line of deposition is about eight or ten miles.” None of the 
bowlders of the Cumberland iron are found to the north of the iron 
mine hill, while to the south they are so abundantly scattered in the 
soil that most of the fences are constructed of them. — Diluvial 
scratches and striz are very numerous, and the direction is generally 
N. 5° E., S. 5° W.—the variation being about 7° 30’ W.—so that the 
direction is very nearly in the meridional line, thus indicating the 
course of the ancient current which has polished the hard rocks more 
or less. : 
“Dr. Jackson carefully collected and analyzed the useful minerals, 
and their extent was measured or estimated with great care. e ex- 
ploration for coal in Cumberland has been abandoned, after penetra- 
ting twenty eight feet through loose materials, and the entire shaft 
was sixty seven feet deep. aoe 
Diamond hill is composed of quartz rock, partially agatized, and 
containing jasper, druses of quartz crystals, phosphate of lime, and 
veins of red hematite iron ore, and is much visited by mineralogists 
on account of the beautiful specimens of agate, chalcedony, and quartz 
crystals, that abound in it, “and which are especially beautiful at its 
summit, where they can be easily broken off from the huge detached 
masses of rock,” as we had occasion many years ago to observe. 
The iron mine hill is a mass of porphyritic magnetic iron ore, 462 
feet in length, 132 feet in width, and 104 feet in height, above the ad- 
joining meadow; containing, at the rate of 240} Ibs. to the cubic foot, 
6,342,336 Ibs., and composed of oxides of iron 40 per cent., silex 23, 
titanium 15, alumina 13.10, magnesia 4, manganese 2. This hill of 
ore seems to have been protruded through the granite and gneiss con- 
temporaneously with the serpentine veins in the vicinity. Its origin 
Would appear to have been the same with that of the iron mines of 
Missouri ; wt 
Near Sneech pond is a remarkable bed of manganese, whose com- 
Position is silex 26.4, protoxide of iron 35.9, protoxide of manganese 
8, carbonic acid 5.2. - : - 
_ Beacon hill, in Cumberland, so called from its displaying a beacon 
light in the American revolution, is composed of_granite. 
Vol. xx, No. 1.—Oct.-Dee. 1840. a. 
