174 THE EALA C0I3TET : 'vol. Ixxviii, 



Dr. A. Wade said that perhaps some observations made by 

 himself might help a Kttle towards the solution of the problem of 

 the Hii'nant Limestone in the area dealt ^vith in this valuable 

 paper. On the eastern side of the Welshpool area the base of the 

 Llandovery was. as a rule, a massive conglomei*ate, sometimes cal- 

 careous and containing Pentamerus. On the north-western flank 

 the conglomerate was still present, bat tended to pass into finer 

 sandstones, and in places thinned out altogether. It was, however, 

 represented by large blocks of limestone, lenticular and non-con- 

 tinuous, which seemed to contain great quantities of Ortliis and 

 similar brachiopods, and practically no JPentamerus. The Llan- 

 dovery here lay unconformably on the L^pper Ordovician rocks, so 

 that the position of the beds was fairly easily determined. Such 

 changes apparently took place in these rocks in the area now 

 described, and possibly such a change accounted for the difficulties 

 in connexion with the Hirnant Limestone. 



Mr. A. K. Wells stated that, as one of the younger workers in 

 Xorth Wales, he wished to add his congratulations and thanks to 

 the Author for her very lucid account of the geology of what was 

 well known to be one of the most difficult areas in that region. 

 He was particularly interested in the discovery of a fossiliferous 

 band in the series of monotonous mudstones that succeed the 

 highest volcanic rocks in the Ai*enig district — a discovery that 

 would go far towards proving the relative age of these lavas. The 

 fauna seemed to be very similar to that found immediately above 

 the volcanic rocks at Llanwrtyd Wells by the s])eaker's colleague, 

 Mr. L. D. Stamp. Here, however, the same graptolites were 

 discovered in another shale-band within the volcanic rocks. The 

 speaker, working in the Ehobell-Fawi' district, a few miles west 

 of Bala, had found similar shales containing; graptolites, which, 

 though poorly preserved, would probably prove to be from the same 

 horizon. 



Mr. C. B. Wedd wished to associate himself with earlier 

 speakers in congratulating the Author on her completion and 

 lucid presentation of a most valuable piece of work. He felt that 

 the structural details were too complex to discuss o:ffhand, and 

 asked whether the Author could give further information as to the 

 effect of the movements upon direction and hade of cleavage. 



Dr. C. A. Matley also cono:ratulated the Author, and enquired 

 whether she had found in the Bala area, at or near the horizon of 

 the Dei-fel Limestone, any representative of the oolitic ironstone 

 which occurred in the Olenkiln Beds of Anglesey and Carnarvon- 

 shire. 



Prof. W. W. Watts congratulated the Author on her courage 

 in tackling so difficult a district. He referred to the interesting 

 point brought out in the paper that the Dei-fel Limestone yielded 

 the • exotic ' fauna, which the Author had particularized in the 

 Stinchar Limestone and elsewhere. He hoped that the time was 

 coming when it would be possible to use only palaeontoiogical 



