116 THE GRANITES OF MAINE. 
Eock structure: The sheets are from 5 to 12 feet thick and hori- 
zontal. Vertical joints, striking N. 60° W., recur at intervals of 10 
feet. There are veins of aplite and of quartz. 
In July, 1905, the plant consisted of a horse windlass and derrick. 
An inclined track leads to the wharf, 400 feet off. 
Product: Random and paving blocks. 
The Seal Core quarries arc in the town of Tremont, on Mount 
Desert Island, about one-half mile southeast of Murphy Hill. Oper- 
ator, S. W. Herrick, Southwest Harbor, Maine. 
The granite (specimen 57, a, from lower opening, collected by 
writer) is a biotite granite of dark-gray shade and medium ( inclining 
to fine) even-grained texture, with feldspar up to one-fourth inch and 
black mica generally under one-tenth inch. It consists, in descending 
order of abundance, of bluish-gray soda-lime feldspar (oligoclase) 
and a little black mica (biotite), together with accessory magnetite. 
The difference in the amount of the two feldspars appears to be less 
than in specimen 57, c, and this granite thus approaches a quartz 
monzonite. There is little contrast between the quartz and feldspars, 
and the biotite plates are small and thinly disseminated. The gran- 
ite (specimen 57, c, probably from the upper quarry, collected by 
the operator) is like specimen <<. except that its color is dark greenish, 
in consequence of the feldspars being greenish gray, and that the 
two feldspars occur in their usual proportions. It contains some 
secondary epidote ami Jakes a fair polish. 
The quarries, opened in L903, consist of several small openings, 
none of which exceed iC> feet square. 
Rock structure: The sheets, from 1 to 3 feet thick, are horizontal 
at the tipper quarry, but dip 10° to 25° W. at the lower one. Vertical 
joints strike 10° to 15° W. and also X. 90° W. The rift is horizontal. 
Sap from 2 to 3 inches thick occurs along the sheets. Dark-gray 
knots, up to 2 inches across, occur occasionally. 
The product, paving blocks thus far. is carted three-fourths mile 
to wharf in Seal Cove. 
The Carroll quarry is in the town of Tremont. on Mount Desert 
island, at Southwesi Harbor. Owned by estate of Jacob YV. Carroll] 
Address, John Carroll, Southwest Harbor. 
The granite (specimen 65, a) is a hornblende granite, of pinkish- 
greenish medium-gray color and medium even-grained texture, con- 
sisting, in descending order of abundance, of pinkish-greenish potash 
feldspar (microcline), smoky quartz, very dark green hornblende, 
and very little black mica (biotite), together with accessory magnetite 
and zircon and secondary chlorite. The microcline is intergrown 
with quartz and soda-lime feldspar (oligoclase-andesine), and is 
largely altered to kaolin and a white mica. This granite is like that 
