138 PROFESSOR JAMES GEIKIE ON THE 



same glacialists, I understand, have nearly completed an elaborate survey of the Eastern 

 Alps, of which they intend shortly to publish an extended account. The results obtained 

 by them are very interesting, and fully bear out the conclusions already arrived at from 

 their exploration of the Bavarian Alps.* A similar succession of glacial epochs has quite 

 recently been determined by Dr Du Pasquier in North Switzerland, t Nor is this kind 

 of evidence confined to the north side of the Alps. On the shores of Lake Garda, 

 between Salb and Brescia, three ground-moraines, separated by interglacial accumulations, 

 are seen in section. The interglacial deposits consist chiefly of loams — the result of 

 subaerial weathering — and attain a considerable thickness. From this Penck infers that 

 the time which has elapsed since the latest glaciation is less than that required for the 

 accumulation of either of the two interglacial series — a conclusion which, he says, is 

 borne out by similar observations in other parts of the Alpine region. J 



Although the occurrence of such subaerial products intercalated between separate 

 morainic accumulations is evidence of climatic changes, still it does not tell us how far 

 the glaciers retreated during an interglacial stage. Fortunately, however, lignite beds 

 and other deposits charged with plant remains are met with occupying a similar position, 

 and from these we gather that during interglacial times the glaciers sometimes retired to 

 the very heads of the mountain valleys, and must have been smaller than their present 

 representatives. Of such interglacial plant-beds, which have been met with in some 

 twenty localities, the most interesting, perhaps, is the breccia of Hotting, in the neigh- 

 bourhood of Innsbruck. § This breccia rests upon old morainic accumulations, and is 

 again overlaid by the later moraines of the great Inn glacier. From the fact that the 

 breccia contains a number of extinct species of plants, palaeontologists were inclined to 

 assign it to the Pliocene. Professor Penck, however, prefers to include it in the 

 Pleistocene system, along with all the glacial and interglacial deposits of the Alpine 

 lands. According to Dr von Wettstein, the flora in question is not Alpine but Pontic. 

 At the time of the formation of the breccia the large-leaved Rhododendron ponticum 

 flourished in the Inn valley at a height of 1200 metres above the sea; the whole 

 character of the flora, in short, indicates a warmer climate than is now experienced in 

 the neighbourhood of Innsbruck. It is obvious, therefore, that in interglacial times 

 the glaciers must have shrunk back, as Professor Penck remarks, to the highest ridges 

 of the mountains. 



We may now glance at the glacial succession which has been established for Central 

 France. More than twenty years ago Dr Julien brought forward evidence to show 

 that the region of the Puy de Dome had witnessed two glacial epochs. |l During the 



* Mittheil. des deutsch. u. oesterreich. Alpenvereins, 1890, No. 20 u. 23. 



+ Beitrdge z. geolg. Karte der Schweiz, 31 Lief., 1891 ; Archiv. d. Sciences phys. et nat., 1891, p. 44. 



| " Die grosse Eiszeit," Hirnmel u. Erde. 



§ Penck, Die Vergletscherung der deutschen Alpen, p. 228 ; Verhandl. d. k. k. geol. Reichsanst., 1887, No. 5 ; Himmel 

 und Erde, 1891. Bohm, Jahrb. d. k. k. geol. Reichsanst., 1884, p. 147. Blaas, Ferdinandeums Zeitschr., iv. Folge ; 

 Bericht. d. nat.-wissensch. Vereins, 1889, p. 97. 



|| Des ph.4norn.hxes glaciaires dans le Plateau central de la France, &c, Paris, 1869. 



