54 FIFTY YEARS GEOLOGICAL RESEARCH IN THE BRISTOL DISTRICT. 
and these rocks were subsequently more fully described by Prof. 
Lloyd Morgan and the present writer 1 (1904). Prof. W. S. 
Boulton 2 added a number of observations on the section at Spring 
Cove near Weston-super-Mare (1904), and the field observations 
from various sources were collected together in a paper published 
in 1904 in the Bristol Naturalists' Society's Proceedings. 3 
The Upper Carboniferous rocks (Coal Measures, etc.) in spite of 
their great economic importance, have been relatively little 
described, but Mr. H. Bolton recorded a marine fauna in the 
lower Coal Measures of the Bristol area in 1907 4 adding further 
details in 191 1. 5 
A considerable amount of attention has been devoted to the 
oldest rocks of the Bristol area, the Silurian, which occur in the 
Tortworth district and in the Eastern Mendips to the north of 
Shepton Mallet. The existence of rocks of this date, in the latter 
area was first recognized by the present writer in 1907. 6 At both 
these localities the Silurian rocks are noticeable from the fact 
that they are associated with contemporaneous volcanic rocks, such 
rocks of Silurian age being almost unknown elsewhere in the 
British Isles. The Tortworth Silurian rocks were described in 
two papers by Prof. Lloyd Morgan (1901) 7 and by Dr. F. R. C. 
Reed 8 (1908) in each case in collaboration with the present writer. 
Further information on the Silurian rocks of the district is con- 
tained in the reports of a committee of the British Association 
appointed for their investigation (Dublin, 1908, Portsmouth, 1911). 
1 Q.J.G.S., Vol. LX, pp. 137-157- 
2 Ibid. pp. 158-169. 
:i Proc. Bristol Nat. Soc, n.s., Vol. X, pp. 188-212. 
4 QJ.G.S., Vol. LXIII, pp. 445-469. 
5 Ibid. Vol. LXVII, pp. 316-341. 
6 Ibid. Vol. LXIII, pp. 217-240. 
7 Ibid. Vol. LyVII, pp. 267-284. 
8 Ibid. Vol. IvXIV, pp. 512-545- 
