322 PREHISTORIC EUROPE. 



however, trie glaciers appear to have been confined to the valleys 

 of the Black Forest, and did not deploy upon the low grounds 

 beyond. 1 



Many years ago M. Collomb described the occurrence of 

 erratic blocks at lofty elevations in the Vosges, which could 

 not have been transported into their present positions by any of 

 the local glaciers, whose moraines now form such conspicuous 

 objects in the bottoms of the valleys. They are met with near 

 some of the highest summits, such as the Ballon de Guebwiller, 

 the Ballon d' Alsace, the Drumont, and the Hoheneck, up to a 

 height of 1000 metres above the valley. The blocks are 

 rounded, weathered, and of a different rock from that on which 

 they rest. They are not striated, and have all the appearance 

 of being extremely ancient, their surfaces being much eroded. 

 They cannot possibly have rolled down from above ; their 

 situation on elevated cols quite excludes that supposition. 

 Their external aspect is so different from that of the erratics of 

 the lower regions, — from which they are separated by a zone 

 500 metres in breadth, over which very few erratics are 

 sprinkled, — that it is difficult, M. Collomb says, to admit that 

 they can belong to the same period. If they were carried by 

 ice the glaciers of the Yosges must then have filled the valleys 

 to overflowing, and, escaping from the mountain-region, must 

 have deployed upon the great plains of the Ehine, where at 

 present no trace of their former presence has been detected. 2 

 But such an extension would be quite in keeping with what we 

 know of the extraordinary development of glacial action in the 

 Morvan and the Central Plateau of France. The action of the 

 Ehine and its tributaries in later times might well have 

 removed any morainic dihris which the older glaciers of the 

 Yosges may have left behind them in the valley of the Ehine 

 itself. 



The same geologist and M. Martins, in their interesting 

 account of the glacier of the valley of Argeles in the Pyrenees, 



1 Mtihlberg : Ueber die erratischen Bildungen im Aargau, 1869, p. 82. 



2 Preuves de Vexistenee d'anciens glaciers dans les Vosges, 1847, p. 141. 



