INTERGLACIAL EPOCHS. 321 



3. Pliocene river-deposits with Mastodon arvemensis, M. Borsoni, etc. 



4. Formation of great conglomerate = moraine profonde of extensive 



mer de glace. Two episodes of fusion. 



5. General melting of ice ; deepening of valleys by aqueous erosion. 



6. Interglacial beds with Elephas meridionalis. 



7. Re-advance of glaciers ; associated freshwater beds with mammoth. 



We are not without evidence in other parts of France of a 

 similar succession of changes. M. Tardy has drawn attention to 

 the occurrence of two distinct deposits of glacial origin in the 

 valley of the Ain, separated from each other hy a long period of 

 time, during which great erosion of the land was effected. 1 The 

 same geologist has also pointed out that a similar succession is 

 met with in the valley of the Rhone, not far from Lyons. 2 

 Between that city and Bourg a conglomerate of glacial origin, in 

 which now and then a striated stone may be found, underlies the 

 old Pleistocene alluvia in which Elephas meridionalis occurs, and 

 these alluvia are in turn overlaid by a more recent erratic deposit, 

 the moraine prof onde of the ancient Rhone glacier. The quartzite 

 conglomerate referred to is made up of stones which show 

 flattened surfaces such as betray their glacial origin, but it is 

 only at rare intervals that they are found with the striae preserved. 

 This is no more than we might expect of an accumulation of the 

 kind, for the stones have been rolled about in torrential waters. 

 In one place, however, M. Tardy observed underneath the ancient 

 interglacial alluvium an erratic deposit, the glacial character of 

 which was evident. The ancient Rhone glacier would thus 

 appear to have made two incursions upon the low grounds of 

 France ; and since the Alpine glaciers of the latest cold epoch 

 do not seem to have flowed out of Switzerland, it would follow 

 that we have evidence so far of three successive glacial epochs 

 in this part of Europe. 



In the Black Forest, as in the Alps, we have evidence of two 

 glacial epochs, during the first of which the glaciers advanced 

 into the valley of the Rhine, and in all probability coalesced 

 in part with the Alpine mers de glace. At the second period, 



1 Bull. Soc. Giol. France, t. iii., 3 e Ser. p. 479. 2 Ibid., 3" Ser. t. iv. p. 285. 



Y 



