214 PEOF. S. H. EEYlSrOLDS ON THE LITHOLOGICAL [vol. Ixxvii, 



obtained from the Carboniferous Limestone Series at Clifton '^ 

 dealt with the former subject, while that ' On the Occurrence of 

 the Genus GirvaneUa in Oolitic Rocks, & Remarks on Oolitic 

 Structure ' ^ contains a full description and anah^sis of the several 

 oolitic bands occurring in the Avon Section. A fairl}^ full account 

 of the microscopical structure of many rock-tjq^es is also to be 

 found in his paper on ' The Building of Clifton Rocks.' ^ Gr. F. 

 Harris* also described and figured an oolite from the Avon Section, 

 the example being from ' near Clifton Bridge ' and probably 

 from J)y 



Other papers alluding to the calcareous algae or other somewhat 

 obscure organisms, the remains of which are found in these lime- 

 stones, are one by Mr. "VVethered, in which 3£itc]ieJdeanicr° is 

 described; a second by the same author dealing with Calcispli(sra^\ 

 and one by H. A. Nicliolson,7 in which descriptions are given 

 of JSLitclieJdeania. Solenopora, and GirvaneUa. Prof. El. J. 

 Grarwood's^ addresses and papers describe a number of these lowly 

 organisms, and give further references to the literature of the 

 subject. 



The lithological succession was broadly described in Yaughan's 

 classical paper on ' The Pala3ontological Sequence in the Carboni- 

 ferous Limestone of the Bristol Area '^ — this will be referred to in 

 the following account as ' Bristol paper.' A nmch greater amount 

 of lithological detail is contained in Vaughan's paper on ' The 

 Avonian of the Avon Grorge,'^^^ referred to below as 'Avon paper.' 

 Two papers hj Mr. E. E. L. Dixon are of the utmost importance 

 in any discussion of Carboniferous Limestone lithology. The first 

 of these is his account of dolomitization,ii the second is contained 

 in a paper by him and Vaughan on the Carboniferous succession in 

 Gower.i2 Iyi this a full description is given of many lithological 

 types which are met with in the Avon Section as well as in the 

 Gower peninsula. In particular, the shallow-water deposits which 

 are so characteristic of much of the lower Cleistopora Beds and of 

 the Sijringotliyris and Semimda Beds are described by Mr. Dixon 



1 Q. J. G. S. vol. xliv (1888) pp. 186-98. 



2 lUd. vol. xlvi (1890) pp. 270-74. 



3 Eep. Brit. Assoc. (Bristol) 1898, pp. 362-63, reprinted in Geol. Mag. 1899, 

 pp. 78-79. 



^ Proc. Geol. Assoc, vol. xiv (1895-96) pp. 76-77 & pi. iv, fig. 8. 



5 Geol. Mag. 1886, pp. 585-36. 



« Q. J. G. S. vol. xliv (1888) Proc. pp. 91-92. 



7 Geol. Mag. 1888, pp. 15-24. 



^ Rep. Brit. Assoc. (Birmingham) 1913, pp. 453-72 : reprinted in Geol. 

 Mag. 1913, pp. 440,490, 545 ; also ' Some New Eock-building Organisms from 

 the Lower Carboniferous Beds of Westmorland' ihid. 1914, pp. 265-71. 



9 Q. J. G. S. vol. Ixi (1905) pp. 181-307. 



1" Proc. Bristol Nat. Soc. ser. 4, vol. i, pt. 2 (1906, issued for 1905) 

 pp. 87-100. 



1^ ' Geology of the South Wales Coalfield : pt. viii — The Country around 

 Swansea ' Mem. Geol. Surv. 1907, pp. 13-20. 



1' Q. J. G. S. vol. Ixvii (1911) pp. 477-567. 



