THERMAL METHODS 



977 



reached. The heavy continuous lines represent contours on the 80° F. 

 isogeothermal surface. It can be seen by inspection of the figure that the 

 highest point on the isothermal surface corresponds very closely to the 

 structurally highest point of the producing zone. 



Similar results were obtained over the Long Beach Field in Los Angeles 

 County, California. Isothermal surfaces exist over the producing structure, 

 and these surfaces follow closely the upper oil-producing strata. 



Traverse Di^stance 



Fig. 600.— Temperature anomaly over a typical anticline. 



Figure 598 shows the temperature anomaly obtained across a traverse 

 over a contact between a limestone series and an intrusive granite. The 

 contact is clearly shown, even though the overburden is approximately 

 40 feet thick. The temperature anomaly along two traverses {A and 5) 

 over a fault is shown in Figure 599. The vertical displacement along the 

 fault is approximately 2700 f eet.f 



The temperature anomaly, at depth, over a typical anticlinal structure 

 is illustrated in Figure 600. It will be noted that the curves rise in passing 



t J. N. A. van den Bouwhuijsen, "The Thermocouple Proves Useful on a Geophysical Survey," 

 Bng. and Mining Jour., Vol. 135, No. 8, Aug. 1934. 



