Geological Society. 313 



GEOLOGICAL SOCIETY. 



[Continued from vol. xxxviii. p. 468.] 



May 12th, 1869.— Prof. T. H. Huxley, LL.D., F.R.S., President 

 in the Chair. 



The following communications were read : — 



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., F.G.S. 



After noticing the apparent bedding of the granite, the author 

 stated that in various places, as at Scarrey and Belstone 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 N. to S. and E. to W. The N. and S. 

 joints were generally nearly perpendicular ; the E. and "W. often in- 

 clined to the N. or S. Descriptions of the chief forms of joints and 

 peculiarities connected 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 massive 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 Bock Basins with it was 

 noticed. Yarious 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 attri- 

 buted. In conclusion, the author stated that these three causes had 

 acted frequently together, and that he considered that to them the 

 origin of the Logans, or Rocking- stones, was often to be attributed. 

 The Logans at Belstone and Thornworthy he attributed to the action 

 of these three causes ; and that at Bippon Tor to bedding and joints. 

 The Drewsteignton Logan he considered a transported block, and 

 the " Nutcrackers " atXustleigh a rock which had rolled down from 

 the high ground above. 



2. " Notes on apparent Lithodomous perforations on the Hills of 

 North-west Lancashire." By D. Mackintosh, Esq., E.G.S. 



The author described certain perforations discovered by him in the 

 limestone rocks near Morecambe Bay at altitudes varying from 200 

 or 300 to 667 feet above the sea. He stated that the course of these 

 perforations seemed to be irrespective of any differences in the 

 hardness of the rock, and hence, and from the regularity and smooth- 

 ness of the cavities, he argued that they could not be the result of the 

 chemical and mechanical action of the atmospheric moisture. The 

 perforations were said to occur chiefly in groups, often ramifying from 

 a common entrance ; and where the actual entrance is preserved, 

 this is narrower than the more deeply seated portions. The author 

 maintained that the hollows described by him had been ground out 



