508 L. Richardson — River Development in Walen. 



along the shore. From Courtown Harbour northwards for about 



2 miles to Duffcarrig Rocks sand-dunes are similarly' developed, 

 forming a nearly continuous line of ridges rising to heights of over 

 50 feet. Thick drift deposits occur behind them, but no pre-Glacial 

 cliff or platform is exposed. At Duffcarrig Rocks solid rock again 

 appears forming the headland, and we can recognize remnants of the 

 rock-cut shelf in a much eroded and fissured condition. From here 

 onwards to Ballymoney, about li miles to the north, fragments of it 

 may be detected in the reefs running across the foreshore, but in no 

 place here is it continuously or well preserved, having been much 

 dissected by later marine erosion. It is on the north side of Eally- 

 money, where the cliffs and foreshore are largely composed of solid 

 rock, that we find it in the most perfect condition. Especially is this 

 the case near the mouth of Kildermot Grlen, where it forms a distinct 

 shelf or platform 10-30 feet wide, and is cut across the edges of the 

 steeply inclined Lower Palaeozoic sedimentary and igneous beds. 

 On this platform rest patches of the old beach deposit, the shingle 

 being cemented together into a hard conglomerate and adhering in 

 places firmly to the platform itself. The pebbles in it are mostly 

 rounded and small, but a few are subangular and measure as much 

 as 6-8 inches in length. The platform ends abruptly at the cliffs 

 behind, the upper portion of which is composed of boulder-clay and 

 glacial gravel ; but it can be proved to pass in below these deposits 

 which rest upon its surface. The pre-Glacial cliff is not exposed. 

 "When followed further north beyond Kildermot Glen, the rock-plat- 

 form attains a general width of 25-30 feet, forming an almost horizontal 

 terrace, 10-15 feet above high-water mark, with a gentle slope 

 seawards, and it has been planed down to a remarkably uniform level 

 across the edges of the steeply dipping and highly cleaved Ordovician 

 calcareous flags, etc. A few large transported boulders of non-local 

 rocks are found resting on the surface of the platform, either partly 

 embedded in the drift of the cliffs or weathered out and lying loose on 

 its surface. One such large subangular mass of diorite measured 

 6x3x2 feet, and another block of coarse grey granite measured 



3 ft. 6 in. X 3 ft. X 2 ft. 6 in. in size, both of them being typical 

 erratics. The pre-Glacial platform has been completely worn away 

 further north towards Kilmichael, where the softer purple and green 

 laminated slates set in, the cliffs composed of these beds rising up 

 nearly vertically from the present beach-level. In Kinahan's Geology 

 of Ireland (1878), p. 253, there is a statement that the " 12 ft. beach '' 

 is seen in many places between Bray Head and Carnsore, and it is 

 probable that he here refers to the above described pre-Glacial platform. 



IX. — Ok River Development in Mid-South Wales. 



By L. Richardson, F.E.S.E., F.G.S. 



rpHE Lower Severn Yalley has been classic ground to students of 

 _L river-development ever since Professor W. M. Davis visited 

 and applied those principles of river-development which he had 

 found so illuminating in his own country. Recorded in print, and 



