﻿part 1] , THE IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 



23 



3. Further Work on the Igneous Rocks associated with the 

 Carboniferous Limestone of the Bristol District. By 

 Sidney Hugh Reynolds, M.A., Sc.D., F.G.S., Professor of 

 Geology in the University of Bristol. (Read April 28th, 

 1915.) 



Contents. 



Page 



I. Introduction 23 



II. Field Relations of the Rocks 24 



III. Petrographical Details 34 



IV. Tables of Chemical Analyses 38 



V. Comparison with Rocks of other Areas 39 



VI. Summary and Conclusions 41 



I. Introduction. 



In 1904 the Geological Society published a paper 1 by Prof. Lloyd 

 Morgan and myself on ' The Igneous Rocks associated with the 

 Carboniferous Limestone of the Bristol District.' Since that date 

 enough additional information has been obtained, largely by 

 digging trial- holes, to justify the present paper. The paper men- 

 tioned above summarizes the previous work on these rocks, and the 

 references there given will not be repeated here. The following 

 further communications have, however, been published : — 



1. Prof. W. S. Boulton, 2 in 1904, recorded many additional observations on 



the lava of Spring Cove, Weston-super-Mare, and its relations to the 

 associated tuff and limestone. Prof. Boulton had already, at the 

 meeting of the British Association at Southport 3 in 1903, given a 

 preliminary account of the section. 



2. In 1904 a paper was published in the Bristol Naturalists' Society's Pro- 



ceedings 4 entitled ' The Field Relations of the Carboniferous Volcanic 

 Rocks of Somerset.' In this paper the field- observations by all previous 

 writers were collected together. 



3. A short paper, 'The Igneous Rocks of the Bristol District,' 5 which I 



prepared for the visit of the Geologists' Association to Bristol in 1907, 

 summarizes the character of these rocks, but contains no fresh in- 

 formation. 



The report by the Directors, 6 on the excursions made during this 

 visit, includes a short account of the Spring- Cove section with a plate 

 of reproductions of photographs. 



4. There is a brief description of these rocks in the chapter on the Palaeo- 



zoic rocks of Gloucestershire and Somerset, in ' Geology in the Field,' 

 the Jubilee volume of the Geologists' Association, 7 published in 1910. 



1 Q. J. G. S. vol. lx, pp. 137-57. 2 Ibid. pp. 158-69. 



3 Rep. Brit. Assoc. (Southport, 1903) p. 660. 



4 N. s. vol. x, pt. 3 (issued for 1903) pp. 188-212. 



5 Proc. Geol. Assoc. vol. xx (1907-1908) pp. 59-65. 



6 Ibid. pp. 154-55 & pi. iv, figs. 1-2. 



7 Pp. 322-23, pi. vi, fig. 2, & pi. vii, figs. 1-2. 



