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DEEP BOREHOLE SURVEYS AND PROBLEMS 



CCi, 200 ft. at right angles. Join AiCi and on AAi and 

 CCi scale off the depth of the hole of intermediate depth, 

 i.e., B = 550 ft., so getting Aa and Cc. Join a to c and 

 where it cuts AiCi at d erect a perpendicular dE to AC. 

 Join EB thus getting the line of strike. From either or 



Fig. 180. 



both of the points A or C drop a perpendicular on to this 

 strike line and complete the right-angle dip triangle by 

 setting off the depth of the point concerned respecting the 



Fig. 181. 



B depth normal to this line. For example, AF is normal 

 to BE the strike and FG = A depth minus B depth = 

 800 - 550 = 250 ft. Hence AGF is the amount of dip. 

 Check with CH normal to strike and HJ = 550 — 200 = 

 350 ft., the difference in depth of C and B. This again 

 gives the amount of dip, and its direction is from F toward 

 A the lowest point. 



