X. 



THE ERRATIC PHENOMENA ABOUT LAKE SUPERIOR. 



So much has been said and written within the last fifteen years, 

 upon the dispersion of erratic boulders and drift, both in Europe 

 and America, that I should not venture to introduce this subject 

 again, if I were not conscious of having essential additions to present 

 to those interested in the investigation of these subjects. 



It will be remarked by all who have followed the discussions re- 

 specting the transportation of loose materials over great distances 

 from the spot where they occurred primitively, that the most minute 

 and the most careful investigations have been made by those geolo- 

 gists who have attempted to establish a new theory of their transpor- 

 tation by the agency of ice. 



The part of those who claim currents as the cause of this trans- 

 portation has been more generally negative, inasmuch as, satisfied 

 with their views, they have generally been contented simply to deny 

 the new theory and its consequences, rather than investigate anew 

 the field upon which they had founded their opinions. Without 

 being taxed with partiality, I may, at the outset, insist upon this 

 difference in the part taken by the two contending parties. For 

 since the publication of Sefstroem's paper upon the drift of Sweden, 

 in which very valuable information is given respecting the phenome- 

 na observed in that peninsula, and the additional data furnished by 

 de Verneuil and Murchison upon the same country and the plains of 

 Russia, the classical ground for erratic phenomena has been left 

 almost untouched by all except the advocates of the glacial theory. 

 I need only refer to the investigations of M. de Charpentier, Escher, 

 Von DerUnth and Studer, and more particularly to those extensive 

 and most minute researches of Prof. Guyot in Switzerland, with- 



