THE CENTURY'S PROGRESS IN GEOLOGY 



lakes which everywhere abound over Northern territo- 

 ries. Some glacialists even hold the view first suggested 

 by Kamsey, of the British Geological Survey, that the 

 great glacial sheet scooped out the basins of many lakes, 

 including the system that feeds the Saint Lawrence. At 

 all events, it left traces of its presence all along the line 

 of its retreat, and its remnants exist to this day as 

 mountain glaciers and the polar ice cap. Indeed, we 

 live on the border of the last glacial epoch, for with the 

 closing of this period the long geologic past merges into 

 the present. 



VI 



And the present, no less than the past, is a time of 

 change. That is the thought which James Button con- 

 ceived more than a century ago, but which his contem- 

 poraries and successors were so very slow to appreciate. 

 Now, however, it has become axiomatic one can hardly 

 realize that it was ever doubted. Every new scientific 

 truth, says Agassiz, must pass through three stages 

 first, men say it is not true ; then they declare it hostile 

 to religion ; finally, they assert that every one has 

 known it always. Button's truth that natural law is 

 changeless and eternal has reached this final stage. No- 

 where now could you find a scientist who would dispute 

 the truth of that text which Lyell, quoting from Play- 

 fair's Illustrations of the Huttonian Theory, printed on 

 the tkle-page of his Principles: " Amid all the revolu- 

 tions of the globe the economy of Nature has been uni- 

 form, and her laws are the only things that have resisted 

 the general movement. The rivers and the rocks, the 

 seas and the continents, have been changed in all their 

 parts ; but the laws which direct those changes, and the 



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