Four strong reflection horizons identified on multichannel seismic-reflection profiles of the U.S. continental margin east of the Carolinas have been traced and contoured (maps A-D). Depths, in kilometers, to the horizons were calculated by the method of Taner and Koehler (1969) using the reflection-time and RMS (root-mean-square) velocities from multichannel velocity analyses. The contoured horizons are continuous traceable reflections on the profiles, indicating that they are surfaces of geological significance. A paleoshelf edge and slope exists on all profiles seaward of the present-day slope. Reflectors cannot be traced from the old shelf into the deep sea, and age estimates for the two areas are derived independently. As a result, the horizons contoured on each map cannot by shown to be synchronous, but they are interpreted to be approximately similar in age. The ages assigned to these horizons under the shelf were determined by projecting reflecting horizons to onshore wells (Brown and others, 1972) and, through a network of seismic profiles, to offshore wells north and south of the map area where units have been dated (Dillon and others, 1979a, b; Schlee, 1981; Paull and Dillon, 1980a) Ages of relectors seaward of the paleoshelf edge were determined by tracing the deep-sea reflecting horizons to DSDP (Deep Sea Drilling Project) wells (Klitgord and Grow, 1980; Tucholke and Mountain, 1979; Paull and Dillon, 1980b).
