Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWEK. 571 



In reply to Mr. Leach and others, he stated that the calcareous 

 ' lagoon-phases ' — the Modiola phases — were all distinguished in 

 places by exceedingly fine-grained calcite-mudstones with an im- 

 poverished fauna of lamellibranchs (especially Modiola), ostracods, 

 and Spirorbis. 1 A certain amount of terrigenous material, mud 

 and fine sand, was found in them all. 



He took exception to Dr. Sibly's remark tbat the Gower area 

 had been exceptionally shallow ; on the contrary, he considered it 

 in many respects typical of the South- Western Province. 



He was very glad to hear from Mr. Wade that the conditions 

 which must have prevailed during lagoon-phases could be approxi- 

 mately paralleled at the present day along the coast of the Hed 

 Sea, as he had not had an opportunity of enquiring whether modern 

 representatives of them were known. The suggestion of Mr. Cosmo 

 Johns that a lowered sea-temperature might account for the absence 

 of dolomite from the Upper Avonian of the North- Western district 

 was welcomed, as the speaker had suspected that the influence of 

 the waters that deposited the Pendleside Shales was beginning 

 to make itself felt there at that time, and a low temperature would 

 also explain the extermination of the previously-rich fauna from 

 the area on the arrival of those waters in force. 



In conclusion, he remarked that, although there appeared to be 

 no reason why lagoon-conditions should not be established during 

 any shallow-water period, it was a matter of observation that they 

 immediately preceded sharp subsidence. 



1 Lack of time prevented the speaker from illustrating the differences between 

 the lagoon-phase deposits and the standard limestones as being similar to those 

 between the Rhsetic — a typical lagoon-phase — and the open-sea Lias. 



Q. J. G. S. No. 268. 2 b 



