Subsurface and Office Representation in Mining Geology 1007 



The area tliat can be mapped on one sheet follows. 



1" = 1' is 8'xlO' 



1" = 10' is 80' X 100' 



1" = 50' is 400' X 500' 



1" = 200' is 1600' X 2000' 



1" = 1000' is 8000' X 10,000' . 



1" = 5000' is 40,000' x 50,000' 



1" = 10,000' is 80,000' X 100,000' 

 All scales of note-sheet areas are even multiples or subdivisions of 

 larger- or smaller-scale note-sheet areas. Detailed sketches, photographs, 

 and microscopic data are posted on tliis type of sheet. 



Assay-Record Sheets — The sheets are identical to note sheets except 

 that they are printed on tracing paper. They may be stapled on the geolo- 

 gic note sheet as overlays. 



Office-Map Geologic Sheets — Office maps have an over-all size of 

 23" X 42'', with a 4" coordinate grid covering a 20" x 40" map area. The 

 ordinate lines are printed or ruled in black on the glazed or reverse side 

 of good-quality tracing cloth. There is a 2'' margin along the north or 

 42" border, and this margin is punched witli four %" holes to fit a 

 24"x43" post binder. Along the other borders of the map area there is 

 a 1'' margin. Location, elevation, and filing data are entered in the lower 

 right-hand margin of the sheet. Ordinate values, engineering data, and 

 culture are posted on the reverse or glazed side of the sheet. The lettering 

 is first penciled on the unglazed side of the sheet and then "mirror" 

 lettered on the glazed side with a LeRoy lettering device and reverse let- 

 tering guides. The unglazed side is reserved for the representation of 

 geology. Identical sheets are used for plan and sectional representation 

 and all map scales (figs. 530, 531, and 532). 



The area covered by each sheet at various scales of representation i.s 

 indicated below: 



r — 50' 1000' X 2000' 



1" — 200' 4000' X 8000' 



1" — 1000' 20,000' X 40,000' 



1" — 5000' 100,000' X 200,000' 



1" — 10,000'....200,000' X 400,000' 

 The 23"x 42" map size is conducive to efficiency because the entire 

 area may be reached without much shifting of person or sheet. The map 

 books handle with ease and consequently maps wear longer. 



Metallization-Ore Reserve-Map Sheets — The sheets are identical to the 

 office geologic-map sheets except that the printing is on clear plastic ma- 

 terial (.005" cellulose acetate). These data are superimposed as an over- 

 lay on the geologic maps. These maps are filed in the same post binder 

 alternately with the geologic maps so that every geologic map is overlaid 

 by a plastic metallization and ore-reserve sheet. Since the superimposed 



