34 THE GRANITES OF MAINE. 
PL III, A, from a photograph of the Ryan-Parker quarry, at the 
southern edge of the dome, shows that the sheets rapidly increase in 
thickness downward — from 1 to 25 feet in a depth of 75 feet — and 
that they dip 20°-25° south. At the next quarry north, the Goss 
quarry (see p. 104), the excavation has exposed the center of the dome 
mass. Here the sheets dip both north, and south, measure from 1 to 
30 feet in thickness, and extend to a depth of fully 110 feet from the 
surface. 
Mosquito Mountain. 2 miles south of Frankfort, in Waldo County, 
is an oval granite dome 545 feet high, with a north-south axis aboul 
1 mile long and measuring about a half mile across. a It has a steep 
east face, the sheet structure of which is shown in PL III, B. On 
the top of this mountain, where the quarry is situated, the sheets dip 
gently north, west, and east, tapering out on the sides, and measure 
from 6 to 15 feet in thickness. At the Mount Waldo quarry, which 
lies 1\ miles north-northwest of the top of Mosquito Mountain, the 
sheets dip 10° and measure from 8 inches to 8 feet in thickness, and 
the excavation averages about 20 feel in depth, about 300 feet from 
north to south, and 400 feet from east to west. The granite here is 
evidently under compressive -train, for the progress of quarrying 
resulted in a vertical fissure, running north-northwest by south-south- 
east for the entire width of the quarry and across the rift,- which is 
horizontal. The formation of the fissure was accompanied by a dull 
explosive noise. At several other quarries in the State foremen 
report a partial closing of vertical drill holes by expansion or com- 
pressive strain of the rock. (See pp. 121, 142.) 
At the White quarry, in Bluehill, the granite breaks with explosive 
sound when split in large sheets along a vertical rift that extends! 
N. 50° W. The gradual increase in the thickness of sheets downward 
is well shown at the Stinchfield quarry, near Hallowell (PL IV, B)\ 
Their evenness and curvature are shown at the Sands quarry, at Vinal- 
haven (PL VI, A). At the Hurricane \>Unu\ quarry ( PL IV, A) the 
excavation is 105 feet deep. The upper sheets measure from 3 to 20 
feet in thickness, but the lowest sheet is fully 60 feet thick. A good! 
cross section of granite sheets is seen at the Crabtree & Havey quarry J 
in Sullivan, shown in PL V, />, which brings out their lenticular form] 
and arrangement. The tapering end of one lens lies between the 
thickest parts of two others. This accounts for the apparent irregu-j 
larity in the thickness of the sheets in some longitudinal sections, not- 
withstanding their progressive thickening downward. Compare PL 
V, A, taken at the same quarry, with PL V. B. PL VIII, B, also 
shows the tapering of the sheets, but here there has been some fault-] 
ing since their formation, as is shown bv the dislocation of the dike. : 
"See Bueksport topographic sheet, U. S. Omi, Su 
rvey 
