456 PROFESSOR GEIKIE ON THE 
enduring kind. One notable exception to the rule that necks form eminences 
at the surface, is furnished by the remarkable vent which occupies a wide 
Fig. 2.—View of Largo Law from the east (the crag on the left, at the base of the cone, is a 
portion of a basalt-stream). 
basin-shaped depression among the Campsie Fells. Yet, beyond its margin 
there occur some conspicuous examples of the usual prominent type, such as 
the Meikle Binn and Dungoil. Though not by any means the largest or most 
perfect of the vents in the basin of the Firth of Forth, the Binn of Burntisland 
presents in detail some of the most strikingly volcanic aspects of scenery 
anywhere to be seen in that region (fig. 14). Consisting of a duil green granular 
volcanic tuff, it rises abruptly out of the Lower Carboniferous formations to a 
height of 631 feet above the sea. Its southern slope has been so extensively 
denuded, that it presents steep craggy slopes and rugged precipices, which 
descend from the very summit of the cone to the plain below—a vertical 
distance of nearly 500 feet. Here and there the action of atmospheric waste 
has hollowed out huge crater-like chasms in the crumbling tuff. Standing in 
one of these it is not difficult to realise what must have been the aspect of the 
interior of these ancient Carboniferous volcanic cones, for the scene at once 
reminds one of the crater-walls of a modern or not long extinct volcano. The 
dull green tuff rises around in verdureless crumbling sheets of naked rock, 
roughened by the innumerable blocks of lava, which form so conspicuous an 
élement in the composition of the mass, Ribs or veins of columnar basalt may 
be seen shooting up the declivities, and standing out prominently as black 
shattered walls. The frosts and rains of successive centuries have restored to 
the tuff its original loose gravelly character. It disintegrates rapidly, and rolls 
down the slopes in long grey lines of volcanic sand, precisely as it no doubt 
did at the time of its ejection, when it fell on the outer and inner declivities of 
the original cone. 
The shape of the vents is on the whole circular or oval; but is subject to 
considerable irregularity. The admirable coast-sections in the east of Fife, 
between Largo and St Monans, as well as those of the shores of Haddington- 
