Subsurface and Office Representation in Mining Geology 993 



data is that little progress has been made during the last half century in 

 the solution and understanding of the processes active in the bringing 

 about of genetically interrelated orogenic effects such as intrusion, differ- 

 entiation, metamorphism, hydrothermal effects, and ore deposits. 



The best-equipped research laboratory available for such study is the 

 field where abundant data is available to the geologist who possesses the 

 training, skill, and initiative to gather and integrate this material. We only 

 need to sharpen the tools that we work with, and great progress and re- 

 vitalization of hard-rock geology is inevitable. At this moment the tool that 

 needs to be sharpened is geologic-representation technique. 



Essentials of Geologic Representation 



Any effective field-underground and office-representation technique or 

 system in terms of purpose and specifications should measure up to the 

 following: 



1. Techniques are such that the average mining geologist can be trained 

 to acquire effective skill in their utilization. If these are overly tedious 

 or slow, mapping and representation is retarded. 



2. Geologists using a given system are calibrated in order that their repre- 

 sentation will conform in qualitative and quantitative intensity so that 

 their collective efforts are» integrated into one set of maps. Two or 

 more geologists working together in one organization are then capable 

 of calibration to a degree that independent mapping of any given area 

 will produce nearly identical representation of geologic values. In 

 cooperative mapping there is no visible break or change in representa- 

 tion where one geologist terminates and the other continues. After a 

 system has been decided upon, there is little place for individualism 

 in geologic representation except in the degree of neatness and preci- 

 sion of note recording and plotting. 



3. Such a system or technique is capable of representing all megascopic- 

 ally visible features. 



4. Representation legend is based on systematic and logical chromatic or 

 geometric sequence and arrangement rather than haphazard use of 

 colors and symbols in order that: 



a. Representation colors and symbols are easily remembered even by 

 non-geological personnel. 



b. The general geology is evident from casual inspection of the maps 

 by the optional ignoring of slight variations in symbol or color 

 utilized to show minor facie variation. By logical grouping of 

 representation symbols or color in such a manner that similar litho- 

 logic values are represented by similar colors, it is possible to 

 interpret readily the map in detail or in generalities. 



c. Qualitative geologic values are as accurately represented graphic- 

 ally as these values can be estimated or determined in the field. 



