CHAP. XXXI 
THE VENTS OF EASTERN FIFE 
87 
A columnar arrangement may often be observed among the basalt 
dykes. When the vein or dyke is vertical, the columns of course seem 
piled in horizontal layers one above the other. The exposed side of the 
dyke then reveals a wall of rock, seemingly built up of hexagonal or poly- 
gonal, neatly fitting blocks of masonry, as in the Lower Carboniferous vent 
of the Binn of Burntisland (Figs. 166, 168). An inclination ot the dyke from 
the vertical throws up the columns to a proportional departure from the hori- 
zontal. Sometimes a beautiful fan-shaped grouping of the prisms has taken 
place. Of this structure the Bock and Spindle, near St. Andrews, presents 
a familiar example (Fig. 222). Much more striking, however, though less 
known, is the magnificent basalt mass of Kincraig, to the west ot Elie, where 
the columns sweep from summit to base of the clift, a height of fully 
150 feet, like the Orgues d’Expailly, near Le Puy in Auvergne. The 
general position of this basalt in the vent is represented in the section 
(B, Fig. 218). The curvature of the basalt is shown in Fig. 223, which is 
taken from the Elie side looking westward, beyond the intrusions, to the 
picturesque cliffs of tuff. The details of the cliff are given in Fig. 225. 
That many of the dykes served as lines of escape for the basalt to the 
outer slopes of the cones is highly probable, though denudation has usually 
destroyed the proofs of such an outflow. A distinct radiation of the dykes 
from the centre of a neck is still sometimes traceable. This structure is 
most marked on the south cone of Largo Law, where a number of hard ribs 
of basalt project from the slopes of the hill. Their general trend is such 
that if prolonged they would meet somewhere in the centre of the cone. 
On the south-east side of the hill a minor eminence, termed the Craig 
Rock, stands out prominently (Fig. 209). It is oblong in shape, and, 
like the. dykes, points towards the centre of the cone. It consists of a com- 
pact columnar basalt, the columns converging from the sides towards the 
top of the ridge. It looks like the fragment of a lava-current which flowed 
down a gully on the outer slope of the cone (B' in 1 ig. 226). 
Veins of basalt are not confined to the necks, but may be seen running 
across the surrounding rocks. The shore at St. Monans furnishes some 
instructive examples of this character. As the veins thin away from the 
main mass of basalt they become more close-grained and lighter in colour, 
and when they enter dark shales or other carbonaceous rocks they pass, as 
usual, into the white earthy clay-like “ white-trap.” The influence of 
carbonaceous strata in thus altering basic dykes and sills may be in- 
structively studied along the shore of the East of Fife. A good instance 
occurs near St. Monans Church (Fig. 227), where a vein of “white-trap 
traverses black shales which have been somewhat jumbled. 
In a modern volcano no opportunity is afforded of examining the contact 
of the erupted material with the rocks through which the vent has been 
opened. But in the basin of the Firth of Forth, within the area now under 
description, a numerous series of coast -sections lays bare this relation in the 
most satisfactory manner. The superincumbent cones of tuft have been 
swept away, and we can examine, as it were, the very roots of the old 
