232 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



glaciation had been repeatedly covered by ice. This view now 

 received more credence, especially after Oswald Heer's re- 

 searches on the palaeontology of the Ice Age in Switzerland 

 discovered the presence of " Interglacial " deposits containing 

 the fauna and flora of a warm, temperate climate, and there- 

 fore betokening a prolonged interruption of the polar con- 

 ditions. 



After Ramsay's brilliant work had proved that almost the 

 whole of Great Britain had been covered by a vast ice-sheet, 

 Kjerulf and Otto Torell demonstrated that Scandinavia had 

 been entirely buried under an ice-sheet some 6000 or 7000 

 feet thick. In South Bavaria, topographical conditions led 

 Captain Stark to suggest that the surface of the plain had been 

 glaciated; and Zittel in 1874, by his discovery of good examples 

 of striated rocks and his determination of typical end and 

 ground moraines, established upon a scientific basis that a 

 great portion of the Bavarian plain had been an ice-field. 



Still, however, the North German geologists held fast to the 

 drift theory of the earlier decades of the century. It is in the 

 memory of many living geologists how that theory received its 

 death-blow in Berlin on the 3rd November 1875. On that 

 evening, at a crowded meeting of the German Geological 

 Society, Otto Torell delivered a powerful address on the course 

 of glacier ice from the central ice-sheet of the Scandinavian 

 plateau to the plains and basins of Northern Europe, and 

 brought home to his Berlin audience with irresistible arguments 

 that the erratics on the North German plain had been dis- 

 persed there by glaciers moving southward. The deep impres- 

 sion made by the eloquent Norwegian was never forgotten ; 

 the drift theory collapsed, and the name of Bernhardi was 

 recovered from oblivion to receive belated honour and be 

 ranked as that of an anticipator of glacial geology. 



The German geological literature was then rapidly enriched 

 by papers on glacial deposits. One of the most effective was 

 contributed by Professor Penck upon the boulder-clay forma- 

 tion of North Germany (Zeitschrift d. D. G. Ges,, 1879). 

 Since then active researches have been continued by the 

 Prussian Geological Survey Department, and it has been 

 shown that there are two distinct series of glacial boulder-clay, 

 separated by interglacial layers containing remains of a rich 

 vegetation. 



Professor Penck in 1882 published a work entitled The 



