Subsurface Laboratory Methods 



159 



a-c plane 

 Angle of plunge 



c vertical 



b - fold axis 



Trace of bedding 

 on cleavage plane 



a-c cleavage or 

 cross joints 



^ Axial plane cleavage trace 

 on bedding plane 



Figure 60. Illustrating a plunging anticline with its elements tied to axes a, b, and c. 



Figure 61. Oriented hand specimen labeled to show its geographic location and 

 space orientatior. The top of the specimen, coordinates, and number are 

 marked on adhesive tape. Some workers prefer to scratch this information di- 

 rectly on the rock. Oriented thin sections are cut from the specimen in the 

 laboratory and marked as shown. The section illustrated is cut parallel to the 

 a-c plane and normal to the b axis. 



