272 Messrs, Jackson and Alger on the 
rocks, then into a more compact breccia, consisting of similar 
masses more closely united, though distinguishable from each 
other, and finally, by consecutive gradations, into a genuine, well 
characterized amygdaloid, in which the most critical eye would 
fail to distinguish its component ingredients. We have in 
our possession specimens from this place, which illustrate per- 
fectly the changes of which we speak, and present these three 
rocks tending to the production of amygdaloid. 
Having thus adverted to the character of this rock in particular, 
we shall notice more generally the appearance of the rocks at this 
place, and then describe the minerals before alluded to as occur- 
ring in them. The shore is fronted by a steep bank about one 
hundred feet high, from the base of. which a slope of débris, de- 
tached by the frost, inclines down into the sea. One half of this 
bank consists of trap, and the other of red sandstone intermixed 
with red shale. Upon it rests alow ridge of columnar trap. 
These two rocks come boldly into contact with each other, and 
the sandstone with the shale, dipping beneath the trap at an angle 
of forty degrees, has the breccia and amygdaloid recumbent on, 
or more properly, inclining against it; thus presenting, when 
viewed from the sea, a section of the two rocks crowned with the 
columnar trap. The amygdaloid is vesicular, and furnishes most 
of the minerals which we are now to describe. They are cha- 
basie, analcime, heulandite, calcareous spar, and siliceous sinter, 
all of which occur abundantly, and are often seen richly congregated 
in the same specimen, or included in the same cavity of the rock. 
The chabasie, grouped with its associated minerals, is usually 
of a wine-yellow or flesh-red color; but in a few instances it is 
nearly colorless and transparent. The crystals, which are fre- 
quently three fourths of an inch in diameter, exhibit the form of 
