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BIVEE-GOEGKES IN COBNWALL AND DEVON. 



75 



because it extended so far inland up finger-like prolongations : as, 

 for example, at Cory ton in the heart of Devon. In the Lydford- 

 Tavistock area the higher platforms were scarcely traceable. Indi- 

 cations of the 1000-foot platform could be seen at Brent Tor and 

 Black Down, but it was very doubtful whether the 750-foot 

 platform was present. 



Mr. C. E. N. Bbomehead said that he had some knowledge of 

 the ground described ; the incised meanders of the Tamar near 

 Grunnislake and Calstock reminded him of those of the "Wye. The 

 diversion of the Upper Lyd by a tributary of the Tamar could also 

 be paralleled in the upper part of the Wye Valley: near Three 

 Cocks Junction the valley took a sudden right-angle bend towards 

 Hay. The ancient valley of the Upper Wye can be followed past 

 Talgarth and Lake Llangorse until it joins the Usk. The capture 

 of that river by a tributary of the Lower Wye gave a quicker 

 immediate fall to the Hereford plain, as in the case described 

 (where a tributary of the Tamar captured the Upper Lyd). The 

 result was also similar, the gorge of the Wye at Llysarn corre- 

 sponding to Lydford Gorge. 



Mr. R. S. Heebies commented on the use of the term ' gorge ' 

 in the paper. The popular meaning of the word was a deep, 

 steep-sided rocky valley, but the speaker thought that .scientifically 

 the use of the word should be restricted to the case of a river 

 which breaches an opposing range of hills. The case of the Avon 

 at Clifton might be the type of such a gorge, and it also fulfilled 

 the popular conception ; while the not far-distant ' gorge ' of the 

 Cheddar Cliffs was only a gorge in the popular sense. The rivers 

 that flowed from the Weald and cut through the North and South 

 Downs, were gorges in the scientific sense, but woiild not be so- 

 called by the man in the street. 



Mr. E. GrEEENLT remarked on the wide bearings of the paper. 

 There were platforms in South Wales and elsewhere about the 

 Bristol Channel. In North Wales, the island of Anglesey was 

 another fragment of such a platform. It was difficult to believe 

 that these platforms could be of widely-different ages, and we 

 might hope that, after a while, it would be possible to begin to 

 correlate them. But there were discrepancies that would need to 

 be reconciled. The platform of Anglesey, for example, was about 

 100 feet lower than the littoral platform of Cornwall. Perhaps, 

 reconciliation might be possible, if one postulated a true submarine 

 platform passing continuously into a base-level of subaerial waste. 

 In such case a difference of 100 feet would constitute no difficulty 

 at such a distance as that of North Wales and the Bristol Channel. 



Prof. W. Gr. Peabnsides agreed that the scenic contrast 

 between the mature topography of the uplands and the vigorous 

 growth of the ravines which are cutting their way back from the 

 Cornish coast is very striking. An equally-abrupt contrast, with 

 similar topographical unconformity along the line at which the 

 ancient valleys ' hang,' can be traced along the nearer hinterland 

 throughout almost the whole western coast of South Britain, both 



