370 Geological Society of London. 



and thus producing actual, though not parallel, superposition of the 

 older rocks. All the arguments which have been used to prove 

 prodigious faulting in the case of the Alps would therefore, the 

 author stated, be quite as applicable to that of the Himalajras. But, 

 as regards the latter range, Mr. Medlicott brought forward evidence 

 which appeared to him sufficient to prove that the present contact 

 of the Sivalik formation with those mountains is the original one, 

 modified only by pressure, without relative vertical displacement; 

 and that the sinking of the mountain-mass is the proximate cause 

 of the contortions of the Tertiary strata. He then endeavoured to 

 show that this explanation is equally applicable to the Alps, espe- 

 cially as it seems also to account for collateral phenomena which 

 appear difficult of explanation consistently with the ordinary hypo- 

 thesis ; and he concluded by discussing the current theories of the 

 formation of lake-basins, in relation to the more immediate subject 

 of his paper. 



2. " On some striking instances of the Terminal Curvature of 

 Slaty Laminse in West Somerset." By D. Mackintosh, Esq., F.G.S. 

 Whilst engaged in investigating the nature and extent of oceanic 

 and atmospheric denudation, and the origin of superficial accumula- 

 tions in the West of England, the author observed, on the nearly 

 level floor of one of the valleys which indent the Quantock Hills, the 

 laminse of Devonian (Carboniferous ?) Slate, very regularly and 

 distinctly bent backwards towards the south. 



Sections near Wiveliscombe exhibited some interesting instances 

 of the curvature of the laminge, the line of demarcation between the 

 commencement of the curving back and the undisturbed mass of 

 slate below, being remarkably distinct and straight when looking 

 along the strike of the cleavage ; but upon looking at right angles 

 to the strike, the surface formed by the edges of the laminae beneath, 

 though as distinctly marked, is very uneven. 



At Raleigh's Cross other instances of the curvature are seen. 

 The most important fact in connection with the sections was thus 

 stated, — the bending and curving back over extensive areas has 

 taken place on perfectly level ground with a declivity instead of an 

 elevation on the side whence the movement must have come. 



An exaggerated continuation of the general curving back is seen 

 at Gupworthy, which at first sight appeared to be part of a denuded 

 anticlinal fold. Instances, much less decided, have also been ex- 

 posed in a cutting of the Exeter and South Devon Eailway near 

 Plymouth, and near Torquay. 



In all parts of Devon, West Somerset, and Cornwall, if not in all 

 districts were the slates are flexible, and where the cleavage laminae 

 dip at a considerable angle to the south, or where they are vertical, 

 with an approximately east and west strike, similar appearances 

 might be discovered, irrespective of the outline and inclination of 

 the ground. 



In the author's opinion the curving back of the slaty laminas in 

 this district must have been produced by a great weight of solid 

 matter propelled in a southerly direction. 



