Vol. 65.] THE 0ED0V1CIAN AND SILUEIAN ROCKS OF CONWAY. 169 



10. The Relation of tlie Oedovician and Silurian Rocks of Conwat 

 (North Wales). By Gertrude L. Elles, D.Sc. (Communi- 

 cated by Dr. J. E. Marr, E.R.S., F.G.S. Read January 27th, 

 1909.) " 



[Plate VIII— Map & Section.] 



Contents. 



Page 



I. Introduction and Literature 169 



II. Succession of the Beds 171 



III. Scenery of the District 173 



IV. Structure of the District 173 



V. Detailed Description of the Beds 175 



VI. Comparison with other Areas 187 



VII. Penological Notes on the Lavas 190 



I. Introduction and Liteeatuee. 



The area constituting the Conway District, for the present purpose, 

 extends from the mountains of Penmaenbach and Dinas on the 

 west, southwards as far as Derwendeg, and thence eastwards to the 

 Conway River, thus including Conway Mountain, and the whole 

 of the country lying immediately north, south-west, and south of 

 the town of Conway itself. On the east side of the estuary there 

 is also the area lying east, north-east, and south-east of the village 

 of Deganwy. 



Literature. 



The region has not hitherto been worked in any detail, wherefore 

 the literature as a whole is scanty and the information somewhat 

 unsatisfactory. The volcanic rocks have received the greatest 

 share of attention, some of the rhyolites, and especially the nodular 

 rhyolites, having been described by Prof. Bonney, Mr. Harker, 

 Prof. Grenville Cole, and others ; but the sedimentary rocks have 

 rarely received more than a general notice. 



The more important papers referring to the district are the 

 following : — 



(A) Stratigraphical. 



Jukes, 1 in his ' Letters,' makes several references to the district; 

 of these the most important statement seems to be that where he 



1 ' Letters & Extracts, &c.' [edited by Mrs. Browne] 1871, p. 440. 



