﻿Vol. 66.~] GEOLOGY OP THE DISTRICT AROUND LLANSAWEL. 419* 



the original type-area of Llandovery itself was still untouched in 

 this respect. He would be glad if the Authors would state whether 

 in the Llansawel area they had observed a great lithological change 

 from the lower dark beds to the upper pale shales and mud- 

 stones of the Gala type, occurring at the horizon where the genus 

 Rastrites made its first appearance. This phenomenon, apparently, 

 was to be seen in all other Yalentian areas in Britain. 



Mr. H. H. Thomas stated that he wished to add his congratula- 

 tions to those of previous speakers. He knew enough of the country 

 described by the Authors to understand the great difficulties that 

 they had to surmount during the four years over which this work 

 extended. The district was one in which cleavage, folding, faulting 

 and poorness of exposures, combined with the high relief of the 

 country, all conspired to make the work arduous. It was most 

 gratifying, therefore, to find that despite all these discouraging 

 factors, the Authors had brought their work to so successful a 

 conclusion. He felt pleased that he had in a measure influenced 

 the Authors in their choice of a district. 



The President (Prof. W '. W. Watts) regretted the absence of 

 Prof. Charles Lapworth and of Dr. Marr. He complimented the 

 Authors on their pluck and persistence in completing so difficult 

 and unpromising a piece of work, and was glad that they had both 

 received the award of the Daniel Pidgeon Fund. The establish- 

 ment of graptolitic horizons in this area marked another advance 

 in the subdivision of the monotonous country of Central Wales. 

 The multiplication of local terms appeared to be a necessary evil, 

 but one which was to be preferred to premature attempts to corre- 

 late the subdivisions with those of such an area as Llandovery, 

 where the succession had not been studied in the light of modern 

 methods. 



Miss Drew, replying for the Authors, in answer to Dr. Herbert 

 Lapworth, said that in the Llansawel district it was the cyphus 

 grits which made by far the most prominent feature in the country 

 occupied by the upper beds ; as far as had been ascertained, there 

 was nothing comparable to the convolutus grits of the Rhayader 

 district. Rastrites peregrinus had not yet been found in the area 

 under consideration, but at the horizon where it should occur there 

 was a distinct change in the lithology, shales with black partings 

 giving way to a series of tough pale-grey mudstones. The grits of 

 Bala age had not been studied in much detail, but they seemed to 

 be of a slightly nodular and impersistent occurrence. In con- 

 clusion, the Authors wished to thank the Fellows most heartily for 

 their very kind reception of the paper. 



