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Louis Agassiz. 



Agassiz or Forbes first discovered the true law of 

 glacial motion, and as to whether Forbes or Tyndall 

 advanced the true theory of glacial motion, it seems 

 to have been almost forgotten that to Agassiz and 

 Guyot is due the credit of something far greater 

 than either the law or the theory of glacial motion. 

 I put aside with bare mention the immense mass of 

 accurate observations accumulated by Agassiz, and 

 embodied in his great works — the Etudes des Glaciers 

 and the Systhne Glaciere, a treasury from which all 

 subsequent writers have drawn. I put aside also all 

 questions as to the laws and the theories of glacial 

 motion, important as they are, as trifling in compari- 

 son. I desire to fix your attention on only one 

 great idea introduced by him, viz, : the idea that 

 glaciers are now, and have been to a much greater 

 extent in a previous epoch, a great geological agents 

 sculpturing our mountains and determining the 

 forms of our continents. 



Let me trace the history of this great idea. 

 Agassiz and Guyot had studied minutely the evi- 

 dences of the former extension of the glaciers of 

 Switzerland. Guyot had even traced the outlines 

 of these ancient glaciers, and thus established the 

 existence of a glacial epoch in that country. With 

 these results still fresh in his mind, Agassiz visited 

 England in 1844 or 1845 (I know not the exact date, 

 nor is it important), and quickly recognised the 

 footprints of glaciers all over the mountains of 

 Wales and Scotland, and astonished the world by 

 announcing that these regions were moulded be- 

 neath an ice-sheet. In 1846 he came to this country, 



