Subsurface and Office Representation in Mining Geology 997 



geologists judge other mining geologists' ability by their skill in taking 

 notes. Some men say this ability is not important; however, these men 

 have one other thing in common — they have never found a pound of 

 ore. 



The System 



Mapping Scales 



The writer has found that the following scales integrate best iHto a 

 mapping system and are adequate for all purposes. 



1. Extreme detail 1" = Y 



2. Detail 1" = 10' 



3. Operating detail 1" = 50' 



4. Semi-detail correlation maps 1" = 200' 



5. Detail reconnaissance and district maps 1" = 1,000' 



6. Sub-regional maps 1" = 5,000' 



7. Regional maps 1" = 10,000' 



8. Smaller scale regional and provincial maps are also useful for district 

 evaluation of regional metallization and geologic trend or pattern. 

 Provincial geologic and metallization representation often results in a 

 better evaluation of local pattern with consequent increase in ore-find- 

 ing efficiency. 



It will be noted (with two exceptions) that the above scales increase 

 progressively in a ratio of 1:5. The exceptions are the ratios between the 

 1' and 10' scale units and the 50' and 200' scales; in the former case the 

 ratio is 1 : 10 and in the latter case 1:4, 



The first two detailed scales mentioned under 1 and 2 are used only 

 when necessary to show extreme detail significant in the interpreation of 

 time or structural relationships. 



There are so many advantages in using the 50' scale detailed unit over 

 the 40' scale unit that the latter scale is obsolete. Some argue that a 40' 

 scale permits more detail than 50' scale mapping; however, it is contended 

 that, inasmuch as the purpose of a larger scale is the representation of 

 small features of less than 1', the difference in width of 1' using the 50' and 

 40' scale is too slight to introduce any practical increase of detailed repre- 

 sentation. 



The difference in area which is mapped on a note sheet of constant 

 size is in the ratio of 12:20; thus, almost twice the amount of area is 

 mapped on a sheet of given size if mapping is done to 50' scale than is 

 mapped on the same sheet using the 40' scale mapping unit. Since 

 more mapping can be accomplished on each sheet, fewer transfers of 

 traverse from one sheet to another are necessary. If the map "quad- 

 rangles" cover standardized unit areas such as 1000' x 2000', the 



