from H = F cos I and Z = F sin I. Regional component values were 
determined, in the same manner, from graphically estimated regionals 
GE (CE) and (E). 
Due to the large angle of inclination, over each seamount, the 
anomalous vertical intensity (Z,) resembles the total magnetic 
intensity in shape and magnitude, whereas the residual horizontal 
intensity closely follows the inverse of the inclination pattern. 
III. ZONE 3 ANOMALIES 
The magnetic features (fig. 4) associated with the continental 
margins (Zone 3 - fig. 3) are linear in nature and form a part of a 
system of anomalies which extends along the coast, from Florida to 
Newfoundland (Drake et al, 1963). Seismic refraction studies, north 
of Cape Hatteras, indicate a major structural system, beneath and 
parallel to the continental margins, consisting of two sedimentary 
troughs separated by a basement ridge (Drake et al, 1958). Relative 
to figure 3, an inner trough is located beneath Georges Bank with 
sediment up to 12,000 feet in thickness. A basement ridge occurs 
near and generally parallel to the 100-fathom curve, and an outer 
trough, with up to 15,000 feet of sediment is located under the 
continental slope and rise. Drake et al (1963), noting a trunca- 
tion of basement contours and an offset in the magnetic anomaly 
pattern near 40°N latitude suggested the existence of a right lateral 
transcurrent fault along this parallel. 
