SEQUEL TO SYSTEMATIC GEOLOGY. 573 



done in English geology. Leopold von Buch had 

 constructed a geological map of a large portion -6f 

 Germany, about the same period ; but, aware of the 

 difficulty of the task he had thus attempted, he still 

 forbore to publish it. At a later period, and as 

 materials accumulated, more detailed maps of 

 parts of Germany were produced by Hoffmann and 

 others. The French government entrusted to a 

 distinguished Professor of the School of Mines, (M. 

 Brochant de Villiers,) the task of constructing a 

 map of France on the model of Mr. Greenough's; 

 associating with him two younger persons, selected 

 for their energy and talents, MM. de Beaumont and 

 Dufrenoy. We shall have occasion hereafter to 

 speak of the execution of this survey. By various 

 persons, geological maps of almost every country 

 and province of Europe, and of many parts of Asia 

 and America have been published. I need not 

 enumerate these, but I may refer to the account 

 given of them by Mr. Conybeare, in the Reports of 

 the British Association for 1832, p. 384. These 

 various essays may be considered as contributions, 

 though hitherto undoubtedly very imperfect ones, 

 to that at which Descriptive Geology ought to aim, 

 and which is requisite as a foundation for sound 

 theory ; a complete geological survey of the whole 

 earth. But we must say a few words respecting 

 the language in which such a survey must be 

 written. 



As we have already said, that condition which 



