M. Cliarpuntier on the Erratic rhcnoiiiena of the North. 71 



We may admit, therefore, that, some time after the last 

 great revolution of the globe, the northern hemisphere was 

 covered by a sheet of snow, from about the 60° parallel to the 

 pole ; and that the snow of the zone comprised between the 

 60° and 70° parallels, was transformed into a glacier, which, 

 in its dilatation, could not extend in any other but a southern 

 direction, because, in other directions, it had to encounter 

 the resistance arising from snow and ice themselves {Essai, 

 § 11). The movement of the glacier must, therefore, have 

 been from north to south. This result of the theory is com- 

 pletely confirmed by the observation of facts, for we know 

 that the general direction of the furrows and scratches traced 

 by the great glacier, is nearly in that du-ection. The slight 

 deviations, sometimes remarked, have been occasioned by the 

 slope and inequalities of the surface. There is likewise an- 

 other fact, which proves conclusively that the movement of 

 the glacier was from north to south. This consists in the 

 fact, that the northern flank of the rocks having been ex- 

 posed to the whole action of the expansive force of the ice, 

 and to that of the movement, presents marks of abrasion and 

 attrition of a much more distinct nature than the flank di- 

 rected towards the south, which, having been more or less 

 sheltered by the body of the mountain, must have experienced 

 to a smaller extent the eft'ect of this action. An argument 

 has been drawn from this fact in favour of the debacle or 

 great northern current ; but the same phenomenon actually 

 takes place under our eyes in the Alps, for, when a glacier 

 encounters a rock or eminence in its passage, we find that the 

 flank turned towards the side whence the glacier proceeds, 

 is always more rounded and more rubbed than that turned 

 towards the opposite direction. 



Lastly, as to the formation of the diluvium, which is met 

 with not only within the limits of the erratic formation, but 

 also to a great distance beyond it, it must have commenced 

 in the first periods of the epoch which we are now considering, 

 and must have gone on augmenting in proportion as the gla- 

 cier was developed. The materials which were deposited, as 

 much by the rivers as by the submarine current, in the re- 

 gions afterwards invaded by the glacier, experienced newdis- 



