The magnetic basement topography and associated magnetic anomaly lineation pattern in an area north of the New England seamounts lying between anomaly 31 and the continental margin were examined in light of the Mesozoic sea floor spreading history of the northwest Atlantic. Within the magnetic quiet zone the crust is typically oceanic as far landward as the slope anomaly and exhibits a normally polarized magnetism in the inner quiet zone. Magnetic lineations have been correlated with the Keathley sequence near Bermuda, and, based upon best estimates of the reversal time scale, cross-strike spreading rates are found to be about 1.7 cm yr-1 from -172 m.y. to -136 m.y. and between 0.9 and 1.0 cm yr-1 from -136 m.y. to -72 m.y. Landward of the Keathley sequence, magnetic anomalies decrease in amplitude, although the intensity of magnetization of the normally polarized crust exhibits average values. Magnetic observations within a large area of the quiet zone surveyed in detail can be fitted to the basement topography if a Jurassic pole position of normal polarity is assumed. However, three zones trending subparallel to the Keathley lineations require a weak reversely polarized magnetism. These low values or remanent magnetization are attributed to either viscous remanence or contamination of original crust by widespread volcanic flows or intrusives during periods of predominantly normal magnetic polarity. The normal and reversed polarity sequence resulting from this study is correlated with the sequence obtained from paleomagnetic measurements on land. Trends of isochrons within this relatively limited oceanic area necessitate an alteration in the shape of the ridge axis. A difference in spreading rate and direction is obvious on either side of the New England seamount chain and is discussed with respect to the history of early plate motions in the northwest Atlantic.