26 James Geikie — On Changes of Climate. 



siderable size, are not infrequently found perched upon the tops or 

 scattered over the slopes of the Kames. By far the greater number 

 of Kames which I have examined contain no erratics whatever, 

 and those which do show an occasional boulder may be of later 

 date than the others. My colleagues' experience is similar to my 

 own ; and as we have now mapped and examined by far the largest 

 areas of Kames that exist in Scotland, it may, perhaps, be assumed, 

 with some degree of certainty, that the occurrence of " included " 

 boulders is the exception. From this and certain other appearances, 

 it seems reasonable to infer that the accumulation of the Kame- 

 series began, at all events, at a time when but little ice, if any, was 

 floating about in the sea. But the quantities of erratics that cumber 

 the surface of the Kames both in Scotland and other northern coun- 

 tries appear to show that after a large proportion of the Kames and 

 cones of sand and gravel had been heaped up, bergs and rafts 

 of ice dotted the surface of, the sea and strewed their burdens of 

 angular debris and boulders over the sea-bottom. 



It has sometimes been argued that the disappearance of the ice- 

 sheet, underneath which the Till accumulated, was caused by the 

 coming in of the sea, consequent upon a subsidence of the land. 

 But if this had been the case, the Kame-series must have been formed 

 at a time when floating-ice was plentifully present : and the gravel 

 ridges ought therefore to be as well stocked inside as outside with a 

 supply of erratics. From the fact that they are not so, I would infer 

 that previous to the commencement of the period of submergence 

 the land-ice had already vanished from the low grounds, and that, 

 consequently, during the early stages of subsidence, and even down 

 to a time when the sea had increased to a considerable depth over 

 the land, no glaciers reached the coast-line. 



We have no certain record of what transpired in the interval that 

 elapsed between the deposition of the last patch of Till and the 

 heaping-up of the earliest mounds of sand and gravel. The gradual re- 

 tirement of the last ice-sheet must have cumbered first the sea-bottom, 

 and then by-and-by the land, with great heaps of angular blocks 

 and rubbish. Long before the ice had entirely vacated the bed 

 of the shallow seas around our coast, it must have so diminished in 

 thickness as to have ceased to be confluent over a large part of 

 Scotland. As the cold decreased, mountain tops and rocky ridges 

 would begin to stand boldly up above the level of the mer de glace 

 and separate it by slow degrees into a series of local glaciers. One 

 by one these would " faint and fail," the little ones of course being 

 the first to die out. But by-and-by even the larger glaciers would 

 melt back from the sea and creep up their valleys. The result 

 of this recession of the glaciers would be to cover both the sea- 

 bottom and the land with stones and rubbish, or moraine matter. 

 And seeing that the Kames seldom or never contain angular 

 erratic blocks (although these occur commonly enough perched upon 

 their slopes), it seems legitimate to infer that the ice had in large 

 measure melted away from the land before submergence ensued, 

 and, consequently, that there is no necessary connexion between the 

 disappearance of the ice and the incoming of the sea. 



