LOUIS AGASSIZ 513 



zoology, though it afterwards came to have a very 

 important bearing on all theories of the distribution of 

 animals and plants. The Swiss naturalist Charpentier 

 had observed that many boulders scattered over the 

 meadows and valleys of Switzerland consisted of rock 

 which did not occur in place in the vicinity. The 

 herders called them roches moutonnees, or "sheep rocks," 

 because they resembled resting sheep and sometimes 

 deceived those in search of their lost animals. As 

 early as 1815 a mountaineer named Perraudin had 

 called attention to these rocks, and had suggested that 

 they had been brought by glaciers which had since 

 melted away. This view was supported by the en- 

 gineer Venetz, and finally was brought before the scien- 

 tific world by Charpentier, who presented convincing 

 evidence. 



Agassiz, then, did not originate this idea; but he The glacial 

 saw that if Charpentier was right, much more followed eory 

 than that able man imagined. If Switzerland had once 

 been buried in ice to the extent claimed, how could 

 the climate producing such an effect be restricted to 

 this small area ? Must not all northern Europe, and 

 even North America, show similar phenomena ? Thus 

 was developed the great glacial theory, which is now a 

 commonplace of geological science. In many countries 

 "erratic boulders," as they are called, were found, and 

 also scratches on the rock left by the grinding masses of 

 ice. Naturally such an astonishing conception was 

 not accepted unchallenged. People said, Why does 

 not Agassiz stick to his fishes, which he understands, 

 instead of setting forth such crazy notions, belonging 

 to a field in which he is no expert ? Gradually, how- 

 ever, the facts came to notice, and geologists were 

 compelled to accept the theory practically as Agassiz 



