1008 



Subsurface Geologic Methods 



overlays contain data supplementary to the geologic maps, there is no 

 purpose in posting engineering, excavation, cultural, or geological data 

 on these sheets. The metallization data is posted on the plastic colori- 

 metrically with acetone-base inks. Ore-reserve blocks are posted with 

 diluted acetone-base inks to facilitate periodic revision. 



Figure 532. Three-dimensional representation of planar and sectional map correlation. 

 Field note-sheet-area subdivisions are also indicated. 



