CARBONIFEROUS VOLCANIC ROCKS OF SOMERSET 193 
stones^ (1 and 14). At the base from low- water up the 
beach, between 30 and 40 feet of highly fossiliferous 
crinoidal limestone (1) appear from under the sea in suc- 
cessive beds, which towards the top pass into a reddish 
banded limestone with thin partings of red clay. The 
argillaceous material probably results from decayed volcanic 
Section of Volcanic Rocks in Carboniferous Limestone. 
Middle Hope, Mouth of Severn, Somerset. 
(By Sir A. Geikie, LL.D., F.R.S., and Mr. A. Strahan, F.R.S.). 
dust, and marks the beginning of the eruptions from the 
vent in this neighbourhood, for above the reddish limestone 
lies a greenish tuff (2) with calcareous bands. Much of this 
band is concealed under the detritus of the beach, but it 
may be more than 12 feet thick. It is followed by a thin- 
bedded limestone (3) crowded with Productus and other 
