GEOLOGICAL MAPS 211 



beneath the superficial deposits. It frequently 

 happens that the available natural evidence renders 

 possible more than one interpretation of the 

 geological structure of a certain area, and it is then 

 that shallow excavations such as railway-cuttings, 

 tunnels, wells and drains, as well as all mining 

 operations, aid the geologist in the correctness of 

 his views. It will thus be seen that after a map has 

 been constructed on the basis of natural exposures, 

 there still remains the patient gathering of informa- 

 tion from all those artificial excavations that may 

 be made from time to time; such new data, by 

 confirming or modifying the position of geological 

 boundaries, enhancing the value of the map by 

 virtue of increased accuracy. 



It must be borne in mind that the possible 

 utility of a geological map varies directly as the 

 scientific character of its mode of construction; 

 for unless the mapping is carried out by observers 

 who are thoroughly acquainted with the principles 

 of geology, and who are capable of calling to their 

 aid those other sciences with which geology is so 

 intimately bound up, the resulting maps will con- 

 tain inconsistencies, misconceptions, and even falla- 

 cies. At the same time if scientific results are to 

 be utilised fully by the community, it is a necessity 

 that those to whom such results are to be of the 

 most practical value should at least understand the 

 principles of the science concerned. 



142 



