5 ° 
THE CARBONIFEROUS VOLCANOES 
BOOK VI 
volcanic action contemporaneous with the formation of these deposits. 
A transverse section of the bed, where thus apparently conformable, is 
shown in Fig. 197. 
Fig. 197. — Section of a bed of Volcanic Breccia in the Carboniferous Slate ; White Bull Head, 
County Cork. 
1 1. Sandstones and shales ; 2. Breccia. 
Further examination, however, reveals that this seemingly regular sequence 
is entirely deceptive. At various points the breccia abruptly truncates the 
sandstones, and involves large pieces of them, as shown in Fig. 198 A. At 
Fig. 198. — Volcanic Breccia invading and enclosing Carboniferous Slate, White Bull Head. 
other places, the lower side of the breccia, or what would be its base if it 
were a regular bed, cuts out the strata and sends veins into them (B). And 
the same structure is visible, on its upper side, or what would he its 
top (C). 
It is clear that these highly-inclined bands of breccia are not con- 
temporaneous with the deposition of the Carboniferous Slate, but have 
been introduced into their position at some time subsequent not only 
to the deposition, but to the disturbance and elevation of the strata. The 
peninsula of White Bull Head is crossed by several other similar bands. 
On Black Bull Head, also, together with abundant felsitic and doleritic 
intrusions, a similar breccia or agglomerate is to be seen. In some parts it 
is compact in texture with spheroidal flinty lumps, and weathers some- 
