398 
THE CARBONIFEROUS VOLCANOES 
BOOK V 
large number of them are concealed under these plateaux. A few appear at 
the surface among the lavas and tuffs, but by far the largest number now 
visible have been revealed by denudation, the escarpments having been cut 
back so as to lay bare the underlying rocks through which the necks rise. 
Thus, along the flanks of the great escarpment that extends from near Stirling 
by Fintry and Strathblane to Dumbarton, more than two dozen of agglomerate 
necks may be counted in a distance of about sixteen miles, while if the necks 
of lava-form material are included, the number of vents must be about fifty. 
Nowhere in Scotland do such necks form a more conspicuous feature in the 
scenery as well as the geology than they do between Fintry and Strathblane, 
where, standing out as bold isolated hills in front of the escarpments, their 
conical and rounded outlines present a striking contrast to the terraced 
escarpments behind them. I would especially refer again to the two 
remarkable cones of Dumfoyn and Dumgoyu above Strathblane (Figs. 
123, 124, 127). Along the west front of the hills between Gourock and 
Ardrossan seventeen agglomerate-vents occur in a distance of sixteen miles. 
In Eoxburghshire a group of large agglomerate-necks is dotted over the 
Silurian country around Melrose and Selkirk^ (see Fig. 130). 
From the evidence of these necks it is plain that the volcanic materials 
The surrounding rocks are sandstones, which are much hardened round the vent in the zone marked by the short 
divergent lines. The arrows mark the direction of dip. See “ Geology of East Lothiau," Mem. Gaol. Survey, p. 44. 
of the plateaux must in each case have been supplied not from great 
■central orifices, but from abundant vents standing sometimes singly, with 
intervening spaces of several miles, often in groups of four or five within a 
single scpiare mile. 
111 this region and farther southward, besides the plateau-eruptions, a later group of puys is 
to be seen, and it is difficult to discriminate between the necks belonging to the two groups. Those 
which lie to the east are probably connected with the plateaiux, those to the west with the puys. 
'The latter arc referred to on p. 475. 
