50 THE GRANITES OF MAINE. 
diameter, at the Sands quarry, and a similar one, 5 feet in diameter, 
at the Webster quarry, both in Vinalhaven. One at the Mount Waldo 
quarry measures 6 by 3 feet and consists of a medium-gray ground- 
mass with porphyritic feldspars up to three-fourths inch and biotite 
scales up to one-brent ieth inch. One at the Andrews & Perkins 
quarries, near Biddeford (p. 179), is 10 feet long. At another 
Biddeford quarry the knots are egg-shaped and occur in clusters. 
At the Tayntor quarry, in Hallowell, there is a belt 5 to 25 feet wide, 
with a course X. 10° E., in which knots are abundant. This crosses 
the flow structure, which strikes N. 35° W. 
In none of the knots i> there a definite boundary separating them 
from the granite, excepting such as is caused by the change in the pro- 
portionate abundance of the darker minerals. The cause of knots is 
not perfectly understood. They are collections (segregations) of the 
darker, heavier, iron-magnesia minerals that took place while the 
rock was in a plastic state. 
(.1 OD] S. 
Small cavities lined with crystals occur in granite. They are 
uncommon in the Maine quarries, but at the Bodwell Granite Com! 
pany's quarry, near Jonesboro (p. L69), there are several about a footi 
in diameter, lined with quartz crystals and epidote. The center oi 
some of these is filled with calcite (lime carbonate) in very obtuse- 
rhombohedra half an inch across. The large aplite vein at the sanu 
quarry has many irregular openings lined with crystals of feldspa] 
and tnuscovite. At the Machias Granite Company's quarry, ileal 
Marshfield (p. 174), there are several geodes, up to G inches in diani 
eter, lined with crystals of feldspar and amethyst, with the centra 
space filled with chlorite, epidote. and calcite. 
Such cavities are attributed to bubbles of steam or gas that wen 
in the rock while it was in a molten state, which gave room for th 
growth of crystals and later became filled with epidote and calcite. 
INCLUSIONS. 
Not to be confounded with " knots.'* although some of them ar 
equally dark and ocean- near them, are irregular or angular pal 
tides of various schistose rocks which the granite incorporate 
into itself during its intrusion. They can usually be distinguishe 
from the knots by their different microscopic structure. Inclusio! 
of this kind occur here and there in the Maine quarries. Thus. { 
the Stimson quarry, in West Sullivan (p. Ill), they measure about 
inch, more or less, across, and consist of a fine-grained plicated biotii 
schist Avith a very little andesine feldspar. 
But inclusions also occur on a large scale. Thus, at tin 4 Freepo 
quarry (p. 78) , 30 feet below the surface of the granite and complete] 
