CAEBONIFEROUS VOLCANIC ROCKS OF SOMERSET 207 
scopio examination shows the oolitic grains distinctly, 
together with the remains of encrinites, etc., and the 
basalt has penetrated, fused, and absorbed the Ijmestone 
along its borders. . . . 
“ In some instances the limestone, more especially that 
occurring as irregular lumps in the tuff, is so cracked and 
broken, evidently during the movement of the flow, as to 
suggest that it must have been hard and consolidated 
before the extrusion of the lava, and was probably torn 
from the vent and ejected with the igneous matter. Small 
oval bodies generally a few inches long occur in the basalt ; 
these, when broken, show a yellow or red shell of carbonate 
of lime, the rest being filled with pure white, secondary 
calcite, and in some cases quartz ; indeed, in a few instances 
rounded or oval bodies up to a foot in length consist en- 
tirely of silica. These may be lumps of limestone, burnt 
and hardened on the outside by the hot lava, their centres 
being subsequently removed in solution, the hollows thus 
formed serving as receptacles for secondary calcite or 
quartz ; while in a few cases the whole lump of limestone 
has been replaced by silica. It is possible, however, that 
some of them may be large vesicles filled with secondary 
minerals. 
“ But in most cases the general behaviour and shape 
of the limestone-masses, particularly between the spheroids 
of basalt, seem rather to suggest that the calcareous 
material must have been only in part consolidated, so that 
it behaved as a pulverulent or more or less plastic sub- 
stance, and got rolled in and picked up by the lava, and 
was able to fit itself in between the moving and distending 
spheroidal masses. 
“ In the account of these Weston rocks by the officers of 
the Geological Survey, it is suggested that the vent from 
which the rocks of Spring Cove were derived lay some- 
where to the west, where now the Bristol Channel lies ; 
Q 
