578 ME. B. H. G00DE ON THE FOSSIL FLORA OF [Julie 1913, 



apparent conformity between the formations is illusory, and con- 

 ceals a great break in the physical history of these regions. 



Further, various parts of the Millstone Grit of South Wales have 

 yielded marine fossils which have been claimed as Pendleside 

 species. If this determination is correct, it is hardly compatible 

 with the Middle Coal- Measure age suggested by the Author. 



These possibilities should be borne in mind before undue weight 

 is attached to the palseobotanical evidence, especially when this 

 appears to contradict the stratigraphical evidence, as also the 

 palseontological evidence derived from a study of other groups of 

 fossils. 



Mr. E. E. L. Dixon commented on the lack of evidence of Lower 

 Coal Measures in South Wales, mentioned by the previous speaker. 

 In Pembrokeshire a continuous sequence from Carboniferous Lime- 

 stone into Coal Measures was, unfortunately, nowhere observable 

 along the south side of the coal-basin, where greater freedom from 

 unconformities might be expected than along the north side. 

 However, there was no doubt that the coast-section north of Tenby 

 included part of the Pendleside Series, and that a considerable 

 thickness of strata intervened between the latter and the lowest of 

 the beds that had yielded a Middle Coal-Measure flora. The rocks 

 were chiefly marine, and had yielded few plants ; again, they were 

 interrupted by several disturbances of unknown magnitude. Hence 

 it would be premature, in the present state of our knowledge, to say 

 that a representative of the Lower Coal Measures does not exist on 

 the south side of the Pembrokeshire Coalfield. South of the main 

 part of the South Wales Coalfield, a representative might possibly 

 be found north of the Carboniferous Limestone of the Gower 

 peninsula ; for there the Pendleside Series, with Glyphioceras 

 spircde, was in evidence and, doubtless, passed up into the Coal 

 Measures through an intermediate series of shales with sandstones. 

 Unfortunately, there was no continuous coast-section. 



Dr.T.E.SiBLY spoke of the difficulties which were being revealed 

 in increasing degree by progress in the zonal investigation of tho 

 Lower and Upper Carboniferous rocks. Palagontological studies had 

 shown that the marine Lower Carboniferous extended to higher 

 horizons in the Midland regions than in South Wales ; while 

 palaeobotanical evidence indicated that the Upper Carboniferous of 

 the Midlands included lower horizons than had been detected in 

 the Upper Carboniferous of South Wales. He suggested that the 

 solution of the problem might ultimately be found in the existence 

 of at least one widespread unconformity or break within the 

 Carboniferous succession of South Wales and the adjoining regions. 



With reference to the question of the age of the Millstone Grit, 

 mentioned by a previous speaker, he drew attention to the fact that 

 the ' Pennant Grit ' transgressed persistently from lower to higher 

 floral horizons in passing eastwards from Pembrokeshire to Mon- 

 mouthshire and the Eorest of Dean ; and he suggested that an 

 explanation involving similar transgression, but upwards from east 



