to indicate the observed color of the chert; but color is now used to indicate 

 the type of chert, and the color of chert is indicated in a separate column. 



Hendricks (1940) uses a set of letters, lines, bars, or graphs without color. 

 If the percentage of the residues, the color of the residues, or the percentage of 

 the constituents is not desired or necessary, the set of symbols used by Hendricks 

 is adaptable. Many of them may be made with a standard typewriter. 



Many methods of plotting residue data have been devised for individual 

 needs and purposes. Three will be discussed here. The writer uses a method 

 called the constituent-percentage method which is illustrated in Figure 5-1. The 

 data and description are plotted with a grid ruling printed on a strip log 100 

 feet to the inch. This scale allows the comparison of residue logs with standard 

 oil-well logs or sections. Other intervals may be used according to the need and 

 desire for detailed description. 



Column 2 shows the percentage of residue in relation to the original sample, 

 and column 3 shows the lithology. The percentage of each constituent in refer- 

 ence to the total residue is plotted in column 4. Thus the percentages of the 

 constituents from a 10-percent residue of the original sample will be shown in 

 the same lateral space as the percentages from a 90-percent residue. Color and 

 symbols with superscripts and overprints in ink over the colored background 

 in column 4 describe and distinguish the constituents. The most specific informa- 

 tion for correlation work appears in this column. Lines representing the color 

 of the cherts are placed in column 6, the color being the same as the actual color 

 of the chert, except that white chert is designated by green. 



The percentage-percentage method is a second method of plotting. By this 

 method the percentage of each constituent is plotted in proportion to its per- 

 centage of the original sample as shown in Figure 5-2. Superscripts and over- 

 prints in ink and color similar to the first method are used for differentiation of 

 the constituents. An expanded scale is required and percentages over 75 are 

 eliminated. 



Residues from all types of samples may be plotted satisfactorily by this 

 method except rotary-tool samples having considerable cavings. The caved 

 material in rotary-tool samples hinders accurate judgment of the percentage of 

 any one constituent in relation to the indigenous portion of the original sample. 

 In all samples, the data for percentage-percentage plotting must be calculated, 

 or a table must be used. A major disadvantage of the method is that a constitu- 

 ent which is 10 percent of a residue, which in turn is 10 percent of the original 

 sample, requires the plotting of a 0.0] space on the log. Such a small 

 space is difficult to plot as well as to identify in later study and correlation work. 

 Though a 10-percent residue is ample for determination, many residues are less 

 than 5 percent. Small but significant and diagnostic constituents would be ob- 

 scure and very difficult to differentiate on a log. This method of plotting has an 

 advantage in showing the percentage relations of the constituents at a glance, 



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