APPLICATIONS OF DIP SHOOTING 131 
This rule may be used only where the point of maximum displacement 
lies within the area under examination. If the fault dies out within 
the area prospected the upthrown side may be distinguished by the 
following rule. If the observer places himself on the downthrown side 
of the fault, facing the fault, positive misclosures in the successive 
traverses which the fault cuts will increase toward the right, while 
negative misclosures will increase toward the left. If neither the end 
nor the point of maximum displacement of the fault lies within the 
traversed areas, the direction of throw can not be determined, as the 
points of maximum positive and negative misclosure lie approximately 
MISCLOSURE IN FEET " SHOT POINT 0 
TOTAL DIP IN FEET WELL ie) 
ALONG PART OF FIGURE 5. PROBABLE FAULT —— 
TRAVERSE ~—<220 ~ SCALE 1.3'= IMILE 
LEGEND 

Fic. 5.—Structure contour map of faulted salt dome showing effect of differential dis- 
placement on closure of traverses. Contour elevations below sea-level. 
midway between the point of maximum displacement and the ends 
of the fault. Therefore the misclosures will all be of like sign in the 
case postulated, and the amount of misclosure will decrease either 
toward the end of the fault, or toward the point of maximum dis- 
placement, or both, the two directions being indistinguishable under 
the circumstances. 
In all of the work examined only two cases of misclosure which the 
writers considered justifiably attributable to faulting were found. One 
of these cases is used here as an illustration of the principles already 
outlined. A portion of the structure-contour map built up on dip- 
reflection data is shown in Figure 5. The significant closed traverses 
are also given, and the amount of misclosure is written in the center of 
each. The fault was first suspected because of the progressive values 
653 
