37 ° 
THE CARBONIFEROUS VOLCANOES 
BOOK VI 
coutiiluity of the volcanic plateau is iiiteri'upted. To the same cause we owe 
tlie occasional reappearance of a portion of the plateau beyond the limits of 
the main mass, as for instance in the detached area whicli occiirs in the 
valley of the (Tariiock above Kilwinning. 
Denudation has likewise come into play, not only in reducing the area of 
the plateau, but in isolating portions of it into outliers, with or without the 
assistance of faults. The site of the Cumbraes and Bute was no doubt at 
one time covered wdth a continuous sheet of volcanic material, and there 
appears to he no reason for refusing to believe that this slieet formed part of 
that which cajis the opposite uplands of Ayrshire. From the southern end 
Fig. 108. — \ lew ot the edge of the ITolcaiiic Plateau .south of Caiiipbeltowii, .Argyllshire. 
The Iijiperijiost of the tliree zones is the voleaiiic series witli its lava-riiigi's. TIio central baud is the Upper Old 
Ked Sandstone, lying tsnifornmiily beneath the l;o'a,s, with its coi-nstone whicli 1ms been quarried. The lowest 
band, tinted dark, i.s the Lower Oid R((d Sandstone, on which the other rocks rest uncoui'ornialdy. 
ol Bute it is only about seven miles across to the sliore of Arran near Corrie, 
where the lavas and tuifs reappear. They are so poorly represented there, 
however, that we are evidently not far from the limit of the plateau in that 
direction. Ho vast has been the denudation of tlie region that it is now 
impossible to determine whether the volcanic ejections of Campbeltown, which 
occupy tlie same geological platform as those of Ai-ran, Bute and Ayrshire, 
were also actually continuous with them. But as the distance between the 
denuded I'ragments of the imlcanie series in Arran and in Cantyre is only 
about 20 miles it is not improbable that this continuity existed, and thus 
that the volcanic accumulations leached at least as far as the southern end 
of Argyllshire, where they now slip under the sea. 
2. The Fast Lothian or Garleton Plateau. — S ome 50 miles to the 
