THE "GREAT ICE AGE." 159 



The leading feature the basis, in fact of this work deserves 

 especial notice, as it gives it a peculiar and timely value of its 

 own. This feature is that the subject as compared with its 

 usual treatment by other leading writers is turned round and 

 presented, so to speak, bottom upward. De Saussure, Char- 

 pentier, Agassiz, Humboldt, Forbes, Hopkins, Whewell, Stark, 

 Tyndall, etc. have studied the living glaciers, and upon the 

 data thus obtained have identified the work of extinct glaciers. 

 Chronologically speaking, they have proceeded backward, a 

 method absolutely necessary in the early stages of the inquiry, 

 and which has yielded admirable results. Geikie, in the work 

 before us, proceeds exactly in the opposite order. Availing 

 himself of th^ means of identifying glacial deposits which the 

 retrogressive method affords, he plunges at once to the lowest 

 and oldest of these deposits, which he presents the most prom- 

 inently, and then works upward and onward to recent glacia- 

 tion. 



The best illustration I can offer of the timely advantage of 

 this reversed treatment is (with due apology for necessary 

 egotism) to state my own case. In 1841, when the " glacial 

 hypothesis," as it was then called, was in its infancy, Professor 

 Jamieson, although very old and nearly at the end of his 

 career, took up the subject with great enthusiasm, and devoted 

 to it a rather disproportionate number of lectures during his 

 course on Natural History. Like many of his pupils, I became 

 infected by his enthusiasm, and went from Edinburgh to Switz- 

 erland, where I had the good fortune to find Agassiz and his 

 merry men at the " Hotel des Neufchatelois" two tents raised 

 upon a magnificent boulder floating on the upper part of the 

 Aar glacier. After a short but very active sojourn there I 

 " did," not without physical danger, many other glaciers in 

 Switzerland and the Tyrol, and afterward practically studied 

 the subject in Norway, North Wales, and wherever else an 

 opportunity offered, reading in the mean time much of its spe- 

 cial literature ; but, like many others, confining my reading 

 chiefly to authors who start with living glaciers and describe 

 their doings most prominently. When, however, I read the 

 first edition of Mr. Geikie's "Great Ice Age," immediately 

 after its publication, his mode of presenting the phenomena, 

 bottom upward, suggested a number of reflections that had 

 never occurred before, leading to other than the usual explana- 

 tions of many glacial phenomena, and correcting some errors 

 into which I had fallen in searching for the vestiges of ancient 



