Geological Society of London. 281 



referring the gravels to the rivers as they at present exist. The ancient rivers had 

 no doubt run at far higher levels than at present. Even the watersheds afford no 

 gauge of the ancient bounds of the rivers. 



Mr. Evans stated his belief that the gravels on the plateau between the Little 

 Ouse and the "Wissey belonged to the Glacial series. He could not agree with the 

 author in limiting the occurrence of the implements to the base of the beds, in 

 ignoring the eroding power of rivers, nor in regarding the deposits at Lakenheath 

 and Vaudricourt as remote from all possible river-action. He maintained that the 

 whole of the phenomena were in accordance with the excavation of the valley, since 

 the highest beds with implements had been deposited near Brandon, and pointed out 

 that a large part of the great plain of the Fens had probably been formed principally 

 by tidal action, since the deposit of the gravel -beds at Shrub Hill. 



Mr. Searles Wood did not think that the valleys of the district under considera- 

 tion had been formed by river-action. Some portion of the upper valleys of the Thet 

 and Little Ouse were intraglacial, and possibly they might be partly due to tidal 

 action. 



Mr. Flower, in reply, could not accept the belief that the process of the manufac- 

 ture of these implements could have been carried on during a lengthened period, or 

 other traces of the men who formed them would have come to light. He stUl 

 thought the French theory of diluvial action was the most in accordance with the 

 phenomena. 



II. — May 12tli, 1869. 1. ''On some of the results arising from 

 the bedding, joints, and spheroidal structure of the Granite on the 

 Eastern side of Dartmoor, Devonshire." By G. Wareing Ormerod, 

 Esq., M.A., E.G.S. 



After noticing the apparent bedding of the granite, the author stated 

 that in various places, as at Searrey and Bolstone Tors on the north, 

 Kestor and Middleton near Chagford, Blackingstone near Moreton, and 

 Houndtor near Ilsington, the beds dipped, and the contour of the 

 country was there caused by these curves. The joints ran in directions 

 mostly from ]^. to S. and E. to "W. The W. and S. joints were gene- 

 rally nearly perpendicular ; the E. and W. often inclined to the N. or 

 S. Descriptions of the chief forms of joints and peculiarities con- 

 nected with them were given ; and it was stated that decay acted along 

 these lines, and that to them the forms of the Tors may be traced. 

 Examples were given showing the effect of joints in the large mas- 

 sive Tor and in the insulated rock pillar. A spheroidal structure was 

 shown to exist in the coarse granite south of the Teign, and the possible 

 connexion of the Rock Basins with it was noticed. Various localities 

 were mentioned where the structure was to be seen in cuttings, and in 

 masses like boulders but actually in situ. To this cause the form of 

 rounded insulated rocks was attributed. In conclusion, the author 

 stated that these three causes had acted frequently together, and that 

 he considered that to them the origin of the Logan, or Bocking-stones, 

 was often to be attributed. The Logans at Belstone and Thornworthey 

 he attributed to the action of these three causes ; and that at Bippon 

 Tor to bedding and joints. The Drewsteignton Logan he considered as 

 a transported block, and the "Nutcrackers" at Lustleigh as a rock, 

 which had rolled down from the high ground above. 



Discussion. — Prof. Ansted had observed similar conditions in Leicestershii'e, 

 Alderney, and elsewhere. The most important feature in the case was the amount of 

 subaerial disintegration and denudation to which the rocks, and especially the Tors, 

 bore witness. The bedding pointed to the metamorphic character of granite ; and in 

 some parts of Corsica this was still more plainly evuiced than in Devonshire. 



Mr. W. W. Smyth agreed that the disintegration of granite was mainly due to the 



