Transform fault delineation is important for determining the direction of plate motion during sea floor spreading. The analysis of marine magnetic anomalies is one of the most powerful geophysical methods for this purpose. In this paper the characteristics of the magnetic anomalies over some transform fault zones in the North Pacific and in the North Atlantic are discussed. From comparison of the characteristics of these magnetic anomalies over transform fault zones with those of the NE-SW anomaly zone in the Davis Strait, the latter anomaly zone is interpreted not as the expression of a transform fault zone caused by horizontal movement during sea floor spreading but as an anomaly zone caused by basalt and therefore is inferred to be the expression of a fault zone produced by vertical crystal movement during volcanic activities. We discuss here the identification and correlation of linear anomalies in the Davis Strait region, and propose our hypothesis on the spreading history of the Davis Strait. Transform fault delineation is important for determining the direction of plate motion during sea floor spreading. The analysis of marine magnetic anomalies is one of the most powerful geophysical methods for this purpose. In this paper the characteristics of the magnetic anomalies over some transform fault zones in the North Pacific and in the North Atlantic are discussed. From comparison of the characteristics of these magnetic anomalies over transform fault zones with those of the NE-SW anomaly zone in the Davis Strait, the latter anomaly zone is interpreted not as the expression of a transform fault zone caused by horizontal movement during sea floor spreading but as an anomaly zone caused by basalt and therefore is in to to the the expression of a fault zone produced by vertical crystal movement during volcanic activities. We discuss here the identification and correlation of linear anomalies in the Davis Strait region, and propose our hypothesis on the spreading history of the Davis Strait.