THE GLACIAL PERIOD AND THE EARTH-MOVEMENT HYPOTHESIS. 227 



The glacial deposits underlying the lignite beds, contain, 

 amongst other erratics, boulders which have come from the 

 upper valley of the Rhine. This means, of course, that the 

 ancient glacier of the Rhine succeeded in reaching the Lake 

 of Zurich; and it is well known that it extended at the same 

 time to Lake Constance. That glacier, therefore exceeded 

 60 miles in length. One cannot doubt that the climatic con- 

 ditions implied by this great extension were excessive, and 

 quite incompatible with the appearance in the low grounds 

 of Switzerland of such a flora as that of the lignites. The 

 organic remains of the lignite beds indicate a climate 

 certainly not less temperate than that which at present 

 characterises the district round the Lake of Zurich. We 

 may safely infer, therefore, that during interglacial times the 

 glaciers of the Alps were not more extensively developed 

 than at present. Again, as the lignites are overlaid by 

 glacial deposits, it is obvious that the Rhine glacier once 

 more reached Lake Zurich — in other words there was a 

 return of the excessive climate that induced the first great 

 advance of that and other Swiss glaciers. That these 

 advances were really due to extreme climatic conditions 

 is shown by the fact that it was only under such conditions 

 that the Scandinavian flora could have invaded the low 

 grounds of Europe, and entered Switzerland. It is im- 

 possible, therefore, that the interglacial flora could have 

 flourished in Switzerland, while the immigration of northern 

 plants was taking place. 



Lignites of the same age as those of Diirnten and Utznach 

 occur in many places both on the north and south sides of 

 the Alpine chain. At Imberg, near Sonthofen, in Bavaria, 

 for example, they are described by Penck* as being under- 

 laid and overlaid by thick glacial accumulations. The 

 deposits in question form a terrace along the flanks of the 

 hills, at a height of 700 feet above the Iller. The flora of 

 the lignite has not yet been fully studied, but it is composed 

 chiefly of conifers, which must have grown near where their 

 remains now occur — that is at 3,000 feet, or thereabout, above 

 the sea. It is incredible that coniferous forests could have 

 flourished at that elevation during a glacial epoch. A 

 lowering of the mean annual temperature by 3° C. only would 

 render the growth of trees at that height almost impossible, 



Die Vergletscherung der deutschen Alpen, 1882, p. 25G. 



