4 PROF. E. J. GARWOOD AND MISS E. GOODYEAR [vol. lxxiv, . 



might have been accumulated under similar lagoon conditions 

 during a period of subsidence. Although the investigation of the 

 district has revealed no rocks of Ordovician age, a careful exami- 

 nation of the Wenlock deposits has shown that the}' include a 

 special reef facies of the Woolhope Limestone, a facies which 

 constitutes by far the most remarkable development 

 of algal limestone yet recorded from British rocks. 



During the progress of this investigation we have had the 

 advantage of discussing many of the problems which arose with 

 Prof. Lapworth, who had himself previously visited and partly 

 mapped the district ; and we are glad of this opportunity of 

 acknowledging our indebtedness to him, not only for the kind 

 and stimulating interest which he has taken in the progress of 

 the work, but also for many valuable suggestions and criticisms. 



We are also indebted to Dr. F. P. Cowper Peed, who has 

 examined our collection of trilobites and brachiopods from the 

 Woolhope Limestone, and has determined many of the species : 

 we wish here to tender to him our sincere thanks for so kindly 

 placing his intimate knowledge of the Wenlock fauna at our 

 disposal. 



To Dr. Herbert H. Thomas we are under special obligation 

 for his kindness in examining microscopic sections of the Pre- 

 Cambrian sediments and for the notes with which he has furnished 

 us. 



In conclusion, we have to acknowledge the courtesv of the 

 managers of the Old Radnor Trading Company and the Radnor- 

 shire Coal & Lime Company for permission to examine the extensive 

 limestone-workings in the neighbourhood. 



II. The Old Padxor Ixlier. (Map, Plate VII.) 



The general structure of the Old Radnor Inlier is an elongated 

 dome, having a longer axis of a mile and three-quarters running 

 in a general north-easterly direction. The northern half of the 

 inlier is occupied, chiefly, by Pre-Cambrian rocks, which form the 

 core of the dome, while the main limestone-mass occurs ini 

 the southern and south-western portions of the inlier. Narrow 

 strips of limestone, however, also occur on the eastern and north- 

 eastern margins, while a small lenticular ' faulted outlier " runs 

 southwards from the northern margin towards the centre of the 

 dome, having been faulted down and preserved in the midst of 

 the Pre-Cambrian rocks. It is probable, therefore, that the lime- 

 stone once extended over the whole of the inlier, and lias been 

 removed from the northern and central portions by denudation, 

 except where certain blocks have been let down and preserved by 

 faulting. According to the Geological Survey map the inlier is 

 surrounded by Wenlock Shale, but there are only three sections 

 where the contact with the limestone is exposed, and in each case 

 the junction is a faulted one. The whole district is much crushed 

 and dislocated by earth-movements. 



