84. ¥ Erratic Pilintionanin about Lake Supérior. 4 oe 
So much has been said and written within the last fifteen veers, -4 
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 sore in the investigation of these subjects.: 
who have followed the discussions’. 
respecting the transpor a of loose materials over great distan- 
ces from the spot where they occurred primitively, that t eae 
minute and the most careful investigations have been made by 
those geologists who have attempted 0 establish a new theory of 
their eraseporaee by the agency of ice. 
TI those who claim pha as the cause of this 
Aiea Te 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 Seng taxed with partiality, I may, at the 
outset, insist upon this difference in the part taken by the two 
contending parties. . since the publication of Sefstroem’s 
paper upon the drift of Esrolen, in which very valuable inform- 
ation 1s given respecting the henomena observed in that penin- 
sula, and the additional roe furnished by de Verneuil and Mur- 
chison upon the same country and the plains of Russia, the clas- 
sical ground for erratic phenomena has been left almost untouched 
ae 
SE eager Le GT 5 
Martins, James Forbes and others, to justify my assertion that no 
important fact respecting the loose materials spread all over Swilt- 
zerland has been added by the advocates of currents since the 
days of Saussure, de Liic, neha? and Von Buch; whilst Prof. 
Guyot has most conclusively shown that the different erratic ba- 
sins in Switzerland are not only distinct from each other, as was 
already known before, but that in each the loose materials are 
arranged in well- determined regular order, showing precise rela- 
tions to the centres of distribution, from which these materials 
originated ; an arrangement which agrees in every particular 
with the arrangement of loose fragments upon the surface of any 
glacier, but which no cause acting, convulsively could have 
produced.* 
about to r piabl of the distribution of the erratic boulders i ebeaetans: will show 
seep faity the identity of the two phenomena. 
