1004 



Subsurface Geologic Methods 



of less than 3^" so that the narrow west or south margin of one sheet may 

 be lapped over the wide east or north margin of the adjacent sheet. The 

 narrow overlap facilitates the transfer of surveys and excavation when a 

 map-area margin is reached. Identical sheets are used for plan and sec- 

 tional representation and all scales of mapping. 



I I !l |i " 



oc 



Microscopic Data t^ 





Detail Sketches, Pliolos 



Figure 529. Diagram showing relative size of areas covered by standard 8%"xH" 

 notebook sheets using various standard mapping scales. It should be noted 

 that smaller-scale map areas are even multiples of larger-scale map areas; 

 this is true only when critical scale values are used. (If metric system is 

 used, letter-size field sheet with 1-cm. grid covering a 20 x 25-cm. map area 

 is used. Metric scale ratios are 1/500, 1/2,000, 1/10,000.) 



