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SCIENCE 



[N. S. Vol. XXV. No. 631 



glaciers, and their agency in the trans- 

 portation of blocks from the Alps across 

 the Swiss lowland to the Jura. It is, in- 

 deed, a curious fact that these Swiss geolo- 

 gists were anticipated, in the conception of 

 the transportation of these blocks through 

 the agency of glaciers, by Playfair, who 

 suggested the idea in 1802. In the early 

 papers of Agassiz the conception of the 

 Glacial period took a form which he him- 

 self later recognized as an exaggeration. 

 He conceived at first of a fall of tempera- 

 ture so wide-spread and so extreme that a 

 polar ice cap extended southward over the 

 whole breadth of Europe and across the 

 Mediterranean, reaching the Atlas Moun- 

 tains. Later he recognized the ice sheet 

 that covered the Alps as entirely separate 

 from the ice sheet of northern Europe. 

 The tendency to an exaggerated view of 

 the Glacial period overcame him again in 

 later years, when he maintained that, at 

 the climax of the Glacial period, there 

 was 'floating ice under the equator, such 

 as now exists on the coasts of Greenland.' 

 Incidentally, he based upon this extrava- 

 gant conception of the Glacial period an 

 argument against Darwin's views of the 

 origin of species, maintaining that the 

 wide-spread cold of the Glacial period pro- 

 duced a general extermination of life, 

 necessitating a new creation. But the ex- 

 travagance of some of his conceptions, and 

 his vain attempt to stop the resistless prog- 

 ress of the doctrine of evolution, may well 

 be forgiven, in memory of the great service 

 which he rendered in bringing into general 

 acceptance the glacier theory of the drift. 

 As Agassiz traveled in various parts of 

 his adopted country, he recognized every- 

 where in the northern states the traces of 

 glaciation, already familiar to him in 

 Switzerland and in Scotland ; and his views 

 found more ready acceptance in this coun- 

 try than in some of the countries of Eu- 

 rope. Guyot, who had been associated with 



Agassiz in the study of the glaciers of 

 Switzerland, came to this country in 1848 ; 

 and he was, of course, a strong ally in the 

 defense of the glacier theory. As early as 

 1841 Edward Hitchcock had been so 

 strongly impressed by the writings of 

 Agassiz that he recognized clearly the 

 traces of glaciers in Massachusetts ; and, in 

 his presidential address before the Associa- 

 tion of American Geologists, and in the 

 postscript to his 'Pinal Report on the Geol- 

 ogy of Massachusetts,' he shows himself 

 almost persuaded to adopt the glacier the- 

 ory for the explanation of the drift in gen- 

 eral. He could not, however, quite bring 

 himself to the acceptance of the conception 

 of a glacier capable of moving with so little 

 slope as to be able to transport material 

 southward over the whole of northeastern 

 America; and he accordingly limited the 

 action of glaciers to those cases in which 

 the drift appeared to be dispersed some- 

 what radially from local centers in moun- 

 tainous or hilly regions. The general 

 southward movement of the drift seemed 

 to him to require the conception of sub- 

 mergence of the land, and transportation 

 by icebergs floating southward from the 

 Arctic regions. As early as 1852, one of 

 the best and most popular text-books of 

 the time, that of Gray and Adams, gave 

 the preference to the glacier theory of the 

 drift. Dana, in his presidential address 

 before the American Association for the 

 Advancement of Science, in 1855, mani- 

 festly inclined to the glacier theory, and, 

 in the first edition of his 'Manual of Geol- 

 ogy,' in 1862, he gave his adhesion more 

 decidedly to that view. The next genera- 

 tion of American students of geology were 

 brought up on the various editions of 

 Dana's 'Manual' and 'Text-book,' so that 

 thenceforward the glacier theory was 

 recognized in this country as orthodox. 

 In some of the countries of Europe the 

 theory of submergence and transportation 



