CHAP. XXXI 
THE VENTS OF EASTERN FIFE 
85 
Many admirable examples may be cited from the shore between Largo and 
St. Monans. Two illustrations of them are given in Figs. 219 and 221. 
In Fig. 219 the dyke is about four feet broad, and is seen to present the 
common transverse jointing as it pursues its way through the tufi. White 
veins of calcite along its margin serve to define its limits. Its position 
in reference to the general body of the neck is shown in the ground- 
plan Fig. 224. The second instance (Fig. 221) is that of a dyke of basalt 
only one foot wide, which runs like a wall up the agglomerate ot the 
Ivincraig neck near Elie. It is seen at the bottom of the cliff projecting 
from the agglomerate ; but higher up it has decayed, leaving its fissure as a 
gaping chasm. Here the general character ot the pyroclastic material is 
well brought out. One or two large blocks may be seen imbedded in it, the 
largest lying above where the dyke bends away to the left. 
The intruded masses vary in breadth from mere threadlike veins up 
to dykes several yards in breadth, which sometimes expand into large 
irregular lumps. They generally consist of some form of basalt : now and 
then, as at Ituddon Point, near Elie, they are amygdaloidal ; and it may be 
observed among them, as among dykes in general, that where the amygda- 
' loidal texture is developed, it is apt to occur most markedly in the central 
part of the vein, the amygdales running there in one or more lines parallel 
with the general trend of the mass. 
That the basalt of these veins and dykes was sometimes injected in an 
extremely liquid condition is shown by its frequently exceedingly close 
homogeneous texture. Within the neck on the shore to the west of Largo, 
the basalt assumes in places an almost flinty character, which here and 
there passes into a thin external varnish of basalt-glass. A farther indica- 
tion of the liquidity of the original rock seems to be furnished by the great 
number of included extraneous fragments here and there to be observed in 
the basalt. 
But besides basalt, other materials may more rarely be detected assuming 
the form of dykes or veins within the necks. Thus, at the Largo neck just 
referred to, strings of an exceedingly horny quartz-felsite accompany the 
basalt — a remarkable conjunction of acid and basic rock within the same 
volcanic chimney. To the east of Elie some dykes, which stand out promin- 
ently on the beach from a platform worn by the sea in a neck, consist of 
an extremely compact volcanic mudstone, stuck full of the worn twin 
crystals of ortlioclase and pieces of hornblende and biotite already noticed. 
So like is this rock to one of the decomposing basalts that its true frag- 
mental nature may easily escape notice, and it might be classed confidently} 
as a somewhat decayed basalt. A considerable amount ot a similar fine 
compact mudstone is to be seen round the edges of some of the Elie vents. 
This material must have been injected into open fissures, where it solidified. 
There is further evidence of the presence of “mud-lava” in some of the 
vents of East Fife, where these orifices contain a remarkable compact 
volcanic sandstone, composed of the usual detritus, but weathering into sphei- 
oidal crusts, so as externally to be readily mistaken for some form of basalt. 
