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[AiSSEMBLY 
sion also. Now the real chemical difference between the granite 
and the dykes is small. Their elements are the same, and to bring 
about a perfect similarity in structure and homogeniety, we have 
only to vary the accidental circumstances v/hich attended their 
formation. The granite is more perfectly crystallized, and the 
feldspar predominates. In the dykes the structure exhibits but a 
trace of crystallization, if any. Now both of these differences are 
to us accidental; the same rock exhibits a difference in structure 
and a difference in the proportions of the materials composing it. 
If we suppose, for a moment, the main rock, that is the granite, to 
have been in a state of igneous fusion, it is plain that so large a 
mass of melted matter must be long in cooling. A more "perfect 
crystalline structure would result, and the elements entering into 
the composition of hornblende and feldspar would be more per- 
fectly separated by chemical attraction. 
Again, if it is admitted that the dykes have been fused, we rea- 
dily see that they should not exhibit a crystalline structure, for the 
quantity of matter in it is comparatively small; it would therefore 
cool rapidly, and but little time would be given for the elements to 
combine regularly, and the matter would be blended more like fur- 
nace slags. Again, it is not improbable that the materials compos- 
ing the dykes were, previous to their injection, a portion of, or in 
contact with, the inferior surface of the granite itself. Or we may 
consider the great mass of the granite above as connected to the 
matter of the dykes beneath^ and during the cooling of the surface, 
which of course would contract, the fluid mass was pressed up- 
wards. It is difficult to conceive of the formation of dykes by 
what is called their cutting agency ; conforming the term to a com- 
mon mode of speaking; thus, it is said that they ^*cut through a 
certain rock." It is more probable that rents existed previously, 
in the rock, and the molten matter was forced into them. The 
subject is however obscure, and it is easier in many cases to ima- 
gine possibilities^ than give a correct rationale. 
It will be perceived that we have not stated the whole argument 
in favor of the Huttonian theory of the origin of granite, but only 
that part of it which is rendered plausible by the phenomena we 
observed at Long-Pond. : 
Those who are familiar with geological phenomena will infer, 
from w^hat has been said, that this district exhibits marks of an- 
