SECT. 1] 



THE MAGNETIC FIELD OVER THE OCEANS 



213 



Location of aeromognetic surveys in the ALEUTIAN ISLANDS and 

 aeromagnetic profiles across ttie ALEUTIAN TRENCH 



55° 



NEAR ISLANDS 



180° 



+ 



NAUTICAL MILES 

 100 200 30 



170' 



Umnak, 



^^:. 



--■iTc,- 



cA=«; 



/~«- 

 -'«-_-> 



Profile 1 



Profile 3 Profile 2 



Profile 8 Profile 7^?°° Profiled '™° 



,'" t^-' 



Profile 4 



Profile 5 



50° 



160° 



150° 



500 y 



500; 



Nautical miles 



20 40 60 



I- 



SCALE 

 VERTICAL SCALE 



f 500 gammas - Total intensity 



500 y Profiles corrected for gradient 

 of Eartfi's main magnetic field 



Sea level 



.JP_QP-fplhpin_s_ 



.EQOOJgthgms. 

 3000 fattioms 



500)' 



Fig. 28. Magnetic and bathymetric profiles across the Aleutian Trench. (After Keller 

 et al., 1954, fig. 10.) 



