PROBLEMS 

 B. TWO-BOREHOLE PROBLEMS 



265 



Two-borehole problems are not very popular and are 

 only resorted to when data for more satisfactory methods 

 cannot be obtained. This is due to the fact that in all 



Fig. 177. 



-{From "Disrupted Strata/' by the courtesy of Crosby, Lockwood 

 & Sons, London.) 



two-borehole computations for the direction of strike of a 

 deposit the resulting conclusions are ambiguous and have 

 to be supplemented by observational data, usually of a 

 geological character, in order that we may decide as to 

 which of the dual answers to adopt. 



a. Two Vertical Boreholes. — To obtain the direction of 

 strike and amount of dip : The amount of dip is found direct 



