The Life and Writings of Agassiz. 21 



And indeed, in order that the Alpine glaciers should ex- 

 tend to the Jura, so as to deposit these blocks " at the eleva- 

 tion of 4000 feet, the valley of Switzerland must have been 

 covered with ice at least 2500 feet thick. Now, such an ac- 

 cumulation of ice could not be the effect of a local cause. 

 The depression of temperature necessary to account for this 

 extension of these glaciers must have made itself felt else- 

 where, and this with an intensity increasing towards the 

 north. Now, as the rocks of Scandinavia present the same 

 marks of friction as the sides of the Alps and the Jura, ac- 

 companied also by erratic boulders, the conclusion was de- 

 duced that all the north of Europe must have been covered 

 by a vast sheet of ice in the same manner as the polar regions 

 are at present. The formation of this sheet-ice, in conse- 

 quence of a sudden depression of the temperature, it was in- 

 sisted, must have put an end to the tertiary epoch, by anni- 

 hilating the animals and plants then existing. 



Such was the original form of the Glacial Theory, which 

 was first announced in a discourse of M. Agassiz in 1837, 

 at the opening of the meeting of the Societe Helvetique, held 

 at Neufchatel. The opposition excited by M. de Charpentier's 

 theory (which only extended the glaciers of the Alps as far 

 as the Jura) was roused in a tenfold degree by that of M. 

 Agassiz. As is always the case when a new truth dawns upon 

 the world, two parties were immediately formed ; one em- 

 bracing the new doctrine with enthusiasm, the other furiously 

 opposing it. Disputes arose even concerning the present 

 glaciers. It was denied that they were capable of polishing 

 and scratching rocks. Doubts were raised as to the mode 

 in which they advanced, and, as the very fact of their advance 

 rested solely on public notoriety, it was demanded that their 

 movement should be shewn by direct observations, before 

 any conclusions were drawn from it. A problem before 

 purely geological, was thus suddenly changed into a question 

 of fact, requiring a long series of researches and experiments. 



Though already overburdened by his various labours, 

 Agassiz did not shrink from his task. He saw at once, that 

 to obtain a satisfactory solution it was not enough to have 

 such isolated observations as can be made on a short visit. 



