1872.] EAMSAY BIVEK-COUESES OF ENGLAND AND WALES. 159 



case that a brook ran along the line of junction, undermining the 

 softer beds, bringing them down into the stream, and then removing 

 them. It was thus that escarpments receded. 



Prof. Morris remarked that at an early period the Alps on the south, 

 and the Cumberland mountains on the north, formed the boundaries 

 of a sort of trough, and that this to some extent must have in- 

 fluenced the flow of the rivers both in Britain and on the Continent. 

 He considered that the series of elevations in pre-Permian times 

 had also much to do with the configuration of some parts of the 

 country, and therefore of its river-basins. The evidence of the 

 Oolitic series was that it was deposited in an area of gradual de- 

 pression, which was subsequently again elevated ; and there was no 

 doubt of the existence of a large amount of land over a great part 

 of Central England during the deposition of some of the later Oolitic 

 beds. Then again came a depression during the period of the 

 White Chalk. With regard to the Severn valley, he recalled the 

 observations of Sir E. Murchison as to its having been an ancient 

 marine channel, connecting the estuary of the Ribble and what is 

 now the Bristol Channel. He cited Prof. PhiUips to account for 

 the presence of the Lickey quartz pebbles in the valley of the Thames 

 by the existence of ancient lochs in the Glacial sea. 



Mr. Whitaker remarked on the probable extension of the Chalk 

 as far as the Scilly Islands, which was evinced by the flints found 

 on the surface there and in the Land's-End district. He attributed 

 the fact of so many of the streams breaking through the chalk 

 escarpment on the south and so few on the north in the London 

 basin to the difi'erence of the dip in the two cases. 



The President could not give in his adhesion to Prof. Ramsay's 

 opinion. To establish so general a view as that propounded, he 

 thought that a more extensive array of facts with regard to the 

 conditions of the river- valleys should have been adduced. He 

 wished for evidence as to the existence of old river-gravels at a 

 greater elevation above the present river Severn, for instance, than 

 that adduced by the author. The elevation of the Alps he regarded 

 as not sufficient to account for the lines of drainage in Britain. It 

 was to be borne in mind that during the Quaternary period the 

 excavatory force of the rivers was much greater than at the present 

 day. He thought there was still much to be learnt as to the causes 

 which led to the direction and extent of the present river-valleys, 

 the original rudiments of which were probably due to other causes 

 than river- action. 



Prof. Eamsat, in reply, was inclined to restrict himself to the 

 immediate subject of his paper. With regard to the so-caUed 

 Straits of Malvern, he accepted the view so far as it assumed that an 

 ancient river-valley had, by submergence, been converted into a 

 strait. He had purposely omitted in his paper all consideration of 

 the Glacial period, for the simple reason that the initial direction 

 of the river- valleys had been given in preglacial times. His object 

 was merely to show the causes of the initial direction of the rivers ; 

 and he could not be expected, in a paper before the Geological 



