260 LOUIS AGASSIZ. 



number of a more extensive work, " Monogra- 

 phic d'Echinodermes." During this year he 

 received a new evidence of the sympathy of 

 the English naturalists, in the Wollaston medal 

 awarded to him by the London Geological 

 Society. 



The summer of 1836 was an eventful one 

 for Agassiz, the opening, indeed, of a new 

 and brilliant chapter in his life. The at- 

 tention of the ignorant and the learned had 

 alike been called to the singular glacial phe- 

 nomena of movement and transportation in 

 the Alpine valleys. The peasant had told his 

 strange story of boulders carried on the back 

 of the ice, of the alternate retreat and advance 

 of glaciers, now shrinking to narrower limits, 

 now plunging forward into adjoining fields, 

 by some unexplained power of expansion and 

 contraction. Scientific men were awake to 

 the interest of these facts, but had consid- 

 ered them only as local phenomena. Venetz 

 and Charpentier were the first to detect their 

 wider significance. The former traced the an- 

 cient limits of the Alpine glaciers as defined 

 by the frame-work of debris or loose material 

 they had left behind them ; and Charpentier 

 went farther, and affirmed that all the erratic 

 boulders scattered over the plain of Switzer- 



