Geologic Implications of Magnetic Surveys — Malahoff and Woollard 
287 
ft 
Fig. 13. Total force magnetic map of the island of Hawaii, based on aeromagnetic profiles flown at 14,000 
over Mauna Kea and Mauna Loa, and at 12,000 ft over the rest of the island. Contour interval at 50 gammas. 
anomalies originate from depths as great as 10 
km below sea level. The absence of anomalies 
over most of the "fundamental fissures” deduced 
from geologic investigations can be explained 
only by an obvious difference in rock material 
from that causing the primary rift zone anoma- 
lies, and a lack of contrast in magnetic suscep- 
tibility of the intrusives filling the secondary 
fissures and the surrounding lavas. 
Although the magnetic anomalies do not 
indicate that the major volcanoes are intercon- 
nected with each other except where two vents 
are located on the same primary rift anomaly, 
this possibility is not ruled out, inasmuch as a 
shallow connection would not have magnetic 
expression if the rock were above the Curie 
temperature. 
In all cases, it is notable that the volcanic 
