258 



James Geikie — On Changes of Climate. 



In a previous paper ^ I remarked that we have no certain record of 

 what transpired in Britain between the final disappearance of the 

 confluent glaciers and the deposition of the esker-drift, — all that we 

 can safely assert is, that "the ice had in large measure melted away 

 from the land before submergence ensued." We are quite sure that 

 a land-surface existed in the British area after the disappearance of 

 the great ice-sheets, and before the accumulation of the kames, 

 although whether our country was continental or not, there is no 

 evidence in Britain to show. But that such may have been the 

 case would appear not improbable from the following considerations. 



If we compare the deposits accumulated during the last intergiacial 

 period in Britain, Switzerland, and, as I have suggested, in Italy, we 

 shall find that movements of elevation and depression have affected 

 the northern and southern regions of Europe alternately. This will 

 be seen at a glance when the separate sections are placed side by side. 

 The series are arranged in descending order : — 



Britain. 

 3. Moraines, brick-clays, and 

 erratics : Land and Sea. 

 [Cold Conditions.] 



ib Kames, sand and 

 gravel : Sea. 

 a ? River deposits, etc. 

 Land. 

 [Mild Conditions.] 

 Glacial deposits. 



2. 



Switzerland. 

 3. Moraines : Land. 



[Cold Conditions.] 

 2. Lignite beds : Land. 



[Mild Conditions.] 

 1. Glacial deposits. 



Italy. 

 Moraines : Land. 



[Cold Conditions.] 



\ a 



b Old alluvia : Land. 

 Sand, etc. Sea. 



[Mild Conditions.] 

 Probably glacial de- 

 posits. 



Many facts seem to show that any considerable subsidence of 

 the earth's crust in one region will be accompanied by a cor- 

 responding elevation in some other area; or, to put it the other 

 way, elevation in one place will be accompanied by subsidence in 

 another. If this view be not unreasonable, it is, to say the least, quite 

 possible that while the north of Italy was being slowly depressed, 

 the British area was being as gradually upheaved. It is true we do 

 not know at what elevation Italy stood above the sea before the 

 depression began, nor can we be quite certain as to the line event- 

 ually reached by the waves along the flanks of the Alps. But the 

 subsidence probably did not greatly exceed 800 feet or thereby below 

 the present level of the Mediterranean ; and we shall perhaps not be 

 deemed extravagant if we assume that before the land began to sink it 

 was at least not less extensive than it is now. Eeturning to Britain — 

 it would not be difficult to show that even after the deposition of our 

 kames had commenced Scotland stood at a level relative to the 



line of tbese suggestions, I was pleased to bear from him that he had long been of 

 opinion that the plain upon which Aosta stands is an old rock-basin filled up with 

 alluvium, and that there are others of the same kind between that and Ivrea. 

 "These are common," he says, "in many of the great Alpine valleys, and in Cumber- 

 land they are very frequent." [Similar phenomena, I may add, occur in Scotland,] 

 There is no reason. Prof. Eamsay thinks, why the old ossiferous alluvium described 

 by Martins and Gastaldi, should be called Pliocene, and perhaps as little for referring 

 to that period the marine sands with shells. These beds might be of the same age as 

 the Cromer Forest bed, or even much younger. 

 1 Geol. Mag., Vol. IX., p. 23. 



