940 



Subsurface Geologic Methods 



/ / ^ ' \/\/^/i 



Figure 501. Simplification of a complex section according to the 

 method shown in figure 500. 



stones in the section shown in figure 500 is 163: 160 + 110 + 45 = 0.51. 

 The value 0.51 is plotted on the map, and all others are computed in a like 

 manner; then the sheet is contoured like an isopach map. A separate ratio 

 map is made for each of the lithologic classes considered in the analysis. 



Percentage Maps 



The percentage contour map is very similar to the ratio map, except 

 that the number used for contouring is the percentage value of sandstones, 

 for example, in the total thickness of the formation. Thus, in the case of 



163 



the log in figure 500, this number is 



478 



0.34. Although the numerical 



values of the contours will be different from those on the ratios map, the 

 appearance of the map should be the same. 



Figure 502. Lithofacies-data sheet. 



