Mineralogy and Geology of Nova Scotia. 279 
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to say which rock is finally subordinate to the other. Near the 
village of Parsborough, the red shale appears to predominate, 
and constitutes a bed more than one hundred yards thick, which 
is beautifully spotted with green, and contains occasionally scat- 
tered crystals of yellow iron pyrites. East of this bed the sand- 
stone appears in more powerful strata, and more than compen- 
sates for the thickness of the shale just mentioned. It forms a 
junction with the trap of Swan’s Creek, where it includes beds of 
the carbonate and sulphate of lime, and where these two salts, so 
opposite in their nature, are seen actually in contact. The lime- 
stone is fragile and slaty, and contains scattered portions of coal ; 
it is also sometimes bituminous. The gypsum is of the laminated 
and fibrous kind, the lamine being sometimes more than a foot 
in length, and of a delicate flesh-color. But the laminated and 
crystallized gypsum is not so much sought for exportation as the 
amorphous varieties. At Tower Hill, twelve miles east of Pars- 
borough, the sandstone again meets the trap, which forms but a 
small part of the precipitous summit, and has no amygdaloid in 
connexion with it. The united sandstone and shale, however, 
exhibit a most singular appearance, and, becoming vesicular, affect 
a curious imitation of amygdaloid, the place of which it occupies 
in relation to the trap. These rocks, forming the base of the pre- 
cipice, are of a fine texture, and contain a large proportion of 
argillaceous matter, colored with peroxide of iron. 
Passing beneath the trap in its immediate vicinity, it abounds 
with compressed and flattened spheroidal cavities, which, instead 
of the zeolites, are, when occupied, filled with rounded masses of 
gypsum, the mineral which usually occurs in this rock. These 
facts obviously tend to establish our theory of the origin of trap- 
tuff and amygdaloid, and render probable the explanation of these 
