Geologic Techniques in Civil Engineering 



1139 



PROBLEM 



METHOD 



RESULTS 



(7A) 

 INTRUSIVE DIKES 



7^ 



7 



7^° "". 



// 



7^ 



& 



/A 



? PRESENCE OF DIKES ? 



(7B) 

 MAGNETIC 



* 



VERTICAL 

 INTENSITY 

 MAGNETOMETER 



INSTRUMENT MEASURES VERY 

 ACCURATELY VALUES OF 

 earth's MAGNETIC VERTICAL 

 MAGNETIC FORCE AT TRAVERSE 

 STATIONS 



TTO) — 



MAGNETIC 



SEE ABOVE 



TRAVERSES ACROSS 

 CRITICAL AREAS 



O.iOOO 



MAGNETIC INTRUSIVE DIKES 

 CAUSE MARKED LOCAL INCREASE 

 IN MAGNETIC VALUES. 



T!m 



PROFILES-VERTICAL MAGNETIC FORCE 



TBaT 



BASALT FLOWS 



? EXTENT OF LOWER FLOW? 



BASALT IS ORDINARILY 

 HIGHLY MAGNETIC. 



LOCAL GEOLOGY FAULT LOCATION 



OB) 

 MAGNETl 



TRAVERSE-VERTICAL MAGNETIC FORCE 

 Li 



SEE ABOVE 



TRAVERSES ACROSS FAULT OR 

 POSSIBLE EXTENSION OF FAULT 



LINE. 



AZ 



60- 



40- 

 20 



\-. 



SS. a CHERT 



\\\ 



^CHERT 

 \ 



FAULTS MAY BE SHOWN BY 

 MAGNETIC CHARACTER OF BEOS. 



Figure 598. Magnetic methods applied to engineering geology. 



