An aeromagnetic survey from the Gulf of Maine to the tip of Florida was conducted in 1964-66. The residual aeromagnetic map shows a continuous magnetic high on or near the continental slope as far south as the 31st parallel. At about the 36th parallel, this anomaly splits into two branches. At the 31st parallel the outer branch swings westward and crosses the coastline near Brunswick, Ga. This continuous magnetic anomaly may result from an igneous intrusive body that parallels the edge of the pre-Paleozoic continental landmass, and suggests that Florida and part of Georgia were added to the paleo-continent in pre-Paleozoic time. Landward from the east-coast anomaly the magnetic field is quite variable, whereas oceanward it has an extremely small gradient. The absence of magnetic anomalieseast of the continental slope suggests that in this region layer 2 may be composed of metamorphosed basalt.