544 HISTORY OF GEOLOGY. 



cases, " we must have a kind of geographical charts, 

 constructed according to the collections of shells 

 found in the earth." But he justly adds, " What a 

 quantity of observations, and what time, would it 

 not require to form uch maps !" 



The execution of such projects required, not 

 merely great labour, but several steps in generaliza- 

 tion and classification, before it could take place. 

 Still such attempts were made. In 1743, was pub- 

 lished, A new Philosophico-chorographical Chart 

 of East Kent, invented and delineated by Christo- 

 pher Packe, M.D. ; in which, however, the main 

 object is rather to express the course of the valleys 

 than the materials of the country. Guettard formed 

 the project of a mineralogical map of France, and 

 Monnet carried this scheme into effect in 1780 7 , 

 " by order of the king." In these maps, however, 

 the country is not considered as divided into soils, 

 still less strata; but each part is marked with its 

 predominant mineral only. The spirit of generali- 

 zation which constitutes the main value of such a 

 work is wanting. 



Geological maps belong strictly to Descriptive 

 Geology ; they are free from those wide and doubtful 

 speculations which form so large a portion of the 

 earlier geological books. Yet even geological maps 

 cannot be usefully or consistenly constructed with- 



1 Atlas et Description Mitieralogique de La France, entreprix 

 par ordre du Roi ; par MM. Guettard et Monnet, Paris, 

 pp. 212, with 31 maps. 



