256 Messrs. Jackson and Alger on the 
This appearance is observed at almost every place where the 
two rocks come in contact. We find the sandstone and the shale 
that occurs with it, gradually putting on the appearance of amyg- 
daloid by admixture with masses of the superinduced trap, effect- 
ed by some disturbing force ; and the amygdaloid, thus produced, 
exhibits the small scales of mica that previously to the union exist- 
ed in the sandstone; but they are deprived of their lustre. Al- 
most every locality furnishes those illustrative specimens, in which 
we detect these fragmentary ingredients, forming first a coarse, 
then a finer, and lastly a true vesicular amygdaloid, the color of 
which, as we have said, depends on the relative portions of its 
materials. These, with other no less interesting and instructive 
phenomena, to which we shall presently allude, give great support 
to the theory of the igneous origin of the trap; and if taken 
together, we believe they cannot be explained without having 
recourse to it. 
Before describing the capes and islands of trap rocks which 
project into the Basin of Mines, or are scattered along its north- 
ern coast, forming the outskirts of the North mountain range, and 
the limits of this interesting formation, it will be necessary to give 
a brief account of the situation and extent of this sheet of water. 
The Basin of Minesis of a scalene triangular shape, and, having its 
longest side formed by the township of Parsborough and the 
district of Colchester on the north, is sixty miles in length. The 
next side, which is forty-five miles long, is formed by the county 
of Hants; and its shortest by the county of Kings, for the dis- 
tance of twenty-five miles. The greatest breadth of this basin 
is from Windsor to Parsborough, thirty miles. It communicates 
with the Bay: of Fundy by a narrow, but deep strait, called 
“the Gut,” which passes between the majestic walls of Cape Split 
and Cape D’Or. 
