198 Proceedings of the Royal Physical Society. 



own day. It is absurd, therefore, to expect to find evidence 

 in Eocene strata of as strongly contrasted climates as those 

 of the glacial and interglacial deposits of the Pleistocene. 

 There must, doubtless, have been alternations of climate in 

 our hemisphere ; but these would consist simply of passages 

 from warm to somewhat cooler conditions — just such changes, 

 in fact, as are suggested by the plants of the English Eocene. 



The evidence of ice-action in the Miocene strata is even 

 more striking than that of which I have just been speaking. 

 The often-cited case of the erratics of the Superga near 

 Turin, I need do little more than mention. These erratics 

 were undoubtedly carried by icebergs, calved from Alpine 

 glaciers at a time when northern Italy was largely sub- 

 merged. The erratic deposits are unfossiliferous, and are 

 underlaid and overlaid by fossiliferous strata, in none of 

 which are any erratics to be found. What is the meaning 

 of these intercalated glacial accumulations ? Can we believe 

 it possible that the Miocene glaciers were enabled to reach 

 the sea in consequence of a sudden movement of elevation 

 which must have been confined to the Alps themselves ? 

 Then, if this be so, we must go a step further, and suppose 

 that, after some little time, the Alps were again suddenly 

 depressed, so that the glaciers at once ceased to reach the 

 sea-coast. For, as Dr Croll has remarked, " had the lowering 

 of the Alps been effected by the slow process of denudation, 

 it must have taken a long course of ages to have lowered 

 them to the extent of bringing the glacial state to a close." 

 And we should, in such a case, find a succession of beds 

 indicating a more or less protracted continuance of glacial 

 conditions, and not one set of erratic accumulations inter- 

 calated amongst strata, the organic remains in which are 

 clearly suggestive of a warm climate. The occurrence of 

 erratics in the Miocene of Italy is all the more interesting 

 from the fact that in the Miocene of France and Spain 

 similar evidence of ice-action is forthcoming. 



Opponents of Dr Croll's theory have made much of 

 Baron Nordenskiold's statement, that he could find no trace 

 of former glacial action in any of the fossiliferous forma- 

 tions within the Arctic regions. He is convinced that "an 



