GLACIERS IN GREAT BRITAIN AND IRELAND. 133 



pass of Llanberris and elsewhere. This opinion, at first 

 received with incredulity, was subsequently confirmed by 

 Mr. Darwin * and Professor Eamsay.f 



The grounds upon which Dr. Buckland rested his con- 

 clusions were precisely those upon which M. Venetz infer- 

 red former extension of the Alpine glaciers. The efiects 

 of these streams of ice moving along their channels have 

 now been repeatedly observed not only in central Europe^ 

 but in the Arctic regions, where they descend into the sea 

 and give origin to icebergs. These effects consist in the 

 polishing and moulding the bottoms and sides of the val- 

 leys into smooth oval bosses, or roches moutonnees — the 

 production of strise, flutings and scratches (which are gene- 

 rally parallel in a given locality) ; also, perched blocks and 

 moraines. The combination of these phenomena in any 

 region can only be attributed to the agency of glacial ice, 

 as there is no other known power capable of producing 

 them. When to these is added the dispersion of erratic 

 blocks, or boulders of large size, over a district extending 

 many miles from the parent masses to which they may be 

 traced, we cannot hesitate to refer the transportation of 

 these blocks to floating icebergs derived from glaciers in a 

 manner similar to that which is in operation along the 

 coast of Greenland, J or amongst the fiords of Tierra del 

 Fuego.§ 



The only districts where, as far as I am aware, a detailed 

 survey of the glacial striee has been accomplished, are 

 those of Snowdon by Professor A. C. Ramsay, || and the 

 mountains of Scandinavia by M. J. C. Horbye.^ In the 

 elaborate work of the latter, extending over the whole Nor- 



* FMlosopMcal Magazine, vol. xxi. p. i8o. 



t PeaJcs, Passes and Glaciers, 4tli edition. 



X Quarterly Journal of the Geological Society of Loadon, vol. is. 



§ Dr. Darwin's Voyage of a Naturalist. 



II Pealcs, Passes and Glaciers, 4th edition. 



% Observations sur les Plienomenes d'erosion en Norvhge. (Christiana.) 



