98 Glacialists and Antiglacialists. 



as to so extensive formation of Ice^ removed ; dificulties on the 

 theory of Currents, the effects contrary to experience of Water- 

 Action. — Erratic phenomena of Lake Superior, — The Iceberg 

 theory. — Description of appearances at Lake Superior. — Drift; 

 contains mud, and is without fossils. — Example ofjuxta-position 

 of stratified and unstratified Drift, at Cambridge. — Date of 

 these phenomena not fully determined, but doubtless simultaneous 

 all over the Globe. — The various periods and kinds of Drift 

 distinguished — Accompanied by change of level in the Continent. 



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 intro- 

 duce this subject again, if I were not conscious of having 

 essential additions to present to those interested in the in- 

 vestigation of these subjects. 



It will be remarked by all who have followed the discus- 

 sions respecting the transportation of loose materials over 

 great distances from the spot where they occurred primi- 

 tively, that the most minute and the most careful inves- 

 tigations have been made by those geologists who have 

 attempted to establish a new theory of their transportation 

 by the agency of ice. 



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

 transportation has been more generally negative, inasmuch 

 as, satisfied with their views, they have generally been con- 

 tented 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 publica- 

 tion of Sefstroem's paper upon the drift of Sweden, in which 

 very valuable information is given respecting the phenomena 

 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 pheno- 

 mena has been left almost untouched by all except the advo- 

 cates of the glacial theory. I need only refer to the inves- 



