208 GEOLOGY AS AN ECONOMIC SCIENCE 



distribution of the useful minerals, the finding of 

 solutions for those structural problems which arise 

 in the course of their exploitation, and the aid it 

 has given in the discovery of new sources of supply. 



Geological Maps. 



Of all the instruments for the furtherance of 

 our commercial welfare that geology has placed in 

 the hands of an educated public, geological maps, 

 undoubtedly, have exerted the most powerful and 

 beneficial influence ; and in the future they will be 

 called upon to play a still more important part as 

 the necessity arises for conserving, and at the same 

 time deriving every possible advantage from, our 

 remaining natural resources. So much of economic 

 value depends upon a correct understanding of the 

 superficial and underground distribution of the 

 geological formations, that a geological map on 

 which the outcrops of the various strata are traced, 

 their inclination given, and the chief lines of dis- 

 ruption indicated, forms the most natural basis for 

 all enquiries concerning the presence and exploita- 

 tion of those useful materials obtained by mining 

 or quarrying, for solving the complex problems 

 connected with water-supply, and for dealing 

 satisfactorily with questions relating to the distri- 

 bution of vegetation. 



The fact that such maps were capable of con- 

 struction was first demonstrated by William Smith, 

 Greenough, and MacCulloch, in the early decades of 



