Results of Magnetic Measures at Sea. Transverse Fractures

Measurements of the total intensity of the magnetic field made by ship-towed magnetometers have permitted the detection of anomalies sometimes exceeding 3000 γ (1γ= 10-5 Oe) on the ridges, while values one-tenth as large are rare on the continents. First results came from the East Pacific where Mason in 1958, then Mason and Raff in 1961 revealed curious parallel anomalies (Figure 13), and concluded Open image in new window Fig. 13 Magnetic anomalies discovered by Raff and Mason in 1961; positive anomalies in black. Faults are indicated by straight lines. Arrows are axes of three ridge segments, from north to south: Explorer, Juan de Fuca, Gorda ridges. (Vine, 1966.) from the sharpness of their edges that they originated in magnetic masses at not over 3 km depth. We begin however as before by considering the mid-Atlantic ridge its regions with a median valley, that is, almost throughout its length.