996 Subsurface Geologic Methods 



are too small for effective interpretation and correlation. The use of 

 many scales is avoided, and the use of "odd" scales, such as 1" = 30', 

 1" = 80', is discouraged. For operating geologic mapping and repre- 

 sentation, scales of 1" = 50' and 1" = 200' will usually suffice. For 

 district maps, smaller scale maps such as 1" = 1000' and 1" = 5000' 

 are useful. 



14. Office maps are not excessively large. The initial cost in tracing cloth 

 is greater than if smaller sheets are used. Large maps are difficult to 

 handle and are soon damaged or destroyed by use. It should be pos- 

 sible to reach any portion of the area without creasing the bottom por- 

 tion of the map over the edge of the table. Map size is standardized 

 for all scales so that blank map stock is procured or prepared at 

 minimum cost, and systematic filing by coordinate value is facilitated. 



15. The note sheet is of standardized size in order that sufficient area is 

 covered on each sheet. Frequent transfer or changing of sheets under- 

 ground or in the field is unnecessary. These sheets are not so large 

 that they are difficult to handle. A letter-size sheet has been found to 

 be the optimum size. 



16. Note sheets and maps are prepared so that coordinate lines are parallel 

 to the edges of the sheets. Nothing presents such an untidy appear- 

 ance as a map with the coordinates at an angle to the margins of the 

 sheet. Then, too, it is difficult to orient directions of structure because 

 most people are accustomed to thinking in terms of the cardinal direc- 

 tions parallel to the edge of the sheet. 



17. Map and note-sheet areas conform to a district wide grid system so 

 that no overlap in the area exists. ^The office-map area is an even mul- 

 tiple of the note-sheet areas. Systematic layout of this type creates 

 efficiency. 



18. The material used in geologic representation is chosen with durability 

 in mind. It is poor economy to post geologic data on tracing paper if 

 the posting is to cost hundreds or thousands of dollars in labor. Oper- 

 ating maps should always be on tracing cloth of good quality. Under- 

 ground and field pencils are waterproof (not "indelible"), and are 

 capable of maintaining fine points. Colored inks used on maps are 

 waterproof. 



19. Maps and note sheets should present a pleasing appearance and should 

 be executed with a sense of artistry. The finding of ore is an art as 

 well as a science. 



20. Good geologic notes and maps must have sales appeal; the geologist 

 uses his maps not only to work out his concepts but to sell them to 

 mine operators. It is important that geologic notes by their very 

 appearance inspire confidence. Nothing is more impressive evidence 

 of the ability of a geologist than a well-executed note sheet or map. 

 The training and skill of a mining geologist is apparent from a very 

 casual inspection of his notes and maps. Most experienced mining 



