166 PBOCEEDINGS OP THE GEOIOGICAL SOCIETY. [Jan. 11, 



garnets, which seem to have come from the Grampian Hills to the 

 north-west showing that the transporting agent had overflowed even 

 the highest parts of the Ochil ridge. And on the West Lomonds in 

 Fifeshire, at the Clattering-well Quarry, 1450 feet high, I found ice- 

 worn pebbles of red sandstone and porphyry in the debris cover- 

 ing the Carboniferous Limestone of the top of the Bishop Hill. Facts 

 like these meet us everywhere : thus on the Perthshire Hills, 

 between Blair Athol and Dunkeld, I found ice-worn surfaces of 

 rock on the tops of hills at elevations of 2200 feet, as if caused by 

 ice pressing over them from the north-west, and transported boulders 

 at even greater heights. 



It was therefore not in the form of narrow glaciers like those 

 of the Alps that the ice existed at this time, but as a thick cake, 

 like that of North Greenland, enveloping both hill and dale, and 

 flowing off, not so much on account of the inclination of the bed on 

 which it rested, as owing to the internal pressure exerted by the 

 immense accumulation of snow over the whole interior of the island, 

 somewhat in the way that a heap of grain flows off when poured 

 down on the floor of a granaiy. The floor is flat, and therefore 

 does not conduct the grain in any direction ; the outward motion is 

 due to the pressure of the particles of grain on one another ; and 

 given a floor of infinite extension, and a pile of grain of suflB.cient 

 amount, the mass would move outward to any distance ; and with a 

 very slight pitch or slope it would slide forward along the incline. 

 • The want of much inclination in the surface of a country, and the 

 absence of great Alpine heights, are therefore objections of no mo- 

 ment to the movement of land- ice, provided we have snow enough. 



Now let us look the matter fairly in the face. It will be found 

 that if instead of land-ice we are to use floating ice, or diluvial 

 action of any kind, for the explanation of the facts, we must do so 

 on a very large scale. These two cases of Schihallion and Morven 

 neatly set before us the extent of the phenomenon, whichever way 

 we are to take it. If we are to adopt the theory of floating ice, we 

 require a submergence of 3000 or 3500 feet to suit these facts; 

 in short, we require to have the whole of Scotland down below 

 water to the top of all but the highest hills, and so with a diluvial 

 action. We cannot take refuge in small local depressions to account 

 for these cases ; we cannot confine the submergence merely to the 

 district of SchihaUion or to that of Morven; for we find on the 

 high ground over all the island (not to speak of Scandinavia) facts 

 that necessitate the application of like conditions. 



Again, if we are to use land-ice as the agency, these two cases 

 are excellently adapted for showing us to what a prodigious extent 

 the snow and ice must have accumulated. 



b. The Boulder-earth or Glacier-mud. — Resting on the surface of 

 the ice- worn rocks we find a widespread accumulation of boulder- 

 earth, an unstratified mass of coarse gritty mud, in which are 

 imbedded pebbles, boulders, and stony particles, often of many dif- 

 ferent kinds, and of all shapes and sizes, from a grain of sand to 

 blocks of considerable weight. These are scattered promiscuously 



