IN THE LAST HALF- CENTURY. 137 



and, to this day, the record of the strati- 

 fied rocks affords no proof that the inten- 

 sity or the rapidity of the causes of change 

 has ever varied, between wider limits, than 

 those between which the operations of 

 nature have taken place in the youngest 

 geological epochs. 



An incalculable benefit has accrued to 

 geological science from the accurate and 

 detailed surveys, which have now been 

 executed by skilled geologists employed 

 by the Governments of all parts of the 

 civilised world. In geology, the study of 

 large maps is as important as it is said to 

 be in politics ; and sections, on a true 

 scale, are even more important, in so far 

 as they are essential to the apprehension 

 of the extraordinary insignificance of geo- 

 logical perturbations in relation to the 

 whole mass of our planet. It should never 



TJieorie de la Terre: 'Pour juger de ce qui est arrive, 

 et meme de ce qui arrivera, nous n'avons qu'a examiner 

 ce qui arrive.' 



