27 6 
Mr. Weaver on the 
The composition of the trap of Pallis varies very much in differ- 
ent parts of the hill. It is frequently of the nature of greenstone 
and basaltic greenstone, and it exhibits also red, brown, grey, and 
green porphyries; but in the north-western quarter basalt more 
particularly predominates, both low down on the northern face, and 
high up on the north-western summit. 
The lowest visible rock at the northern foot, in the plantation at 
Linfield, is a compound of pale greenish trap and calcareous spar ; 
but in the vale below, the bluish grey limestone is quarried in con- 
tinuous strata four and five feet thick, dipping 10° toward the south. 
Above the green trap in the plantation, are the remains of some 
slight mining trials, made a few years since in quest of coal, by 
which, it is said, some little wood-coal was obtained. The trials 
appear to have been conducted in a black carbonaceous slate clay, 
of which a small portion is visible in the road leading to the hill; 
and this appears to support red iron clay stone, which gradually 
passes into and supports amorphous trap, which last is covered by 
columnar basalt. This basalt is quarried for building stone and 
other purposes, and a colonnade is thus exposed to view 70 to 80 
feet in height, facing the north, and about 60 yards in breadth. 
The columns are inclined toward the north under an angle of 75° j 
but the bed which they compose is slightly inclined toward the 
south; they are of irregular figures, disposed toward the four, five, 
and six-sided form, and from two to five feet thick ; and consist 
either of genuine basalt, or of compact basaltic greenstone, both 
containing more or less of hornblende, and displaying by weathering 
large globular distinct concretions, which are composed of concentric 
lamellar layers. 
Below the columnar basalt, but not in contact with it, may be 
observed in the public road to the eastward, many varieties of por- 
