Extended Data Figure 4: Atlantic seafloor and radiocarbon distributions.

a, d, Zonally summed seafloor areas as a function of latitude and depth. b, e, Zonally summed incrop areas as a function of latitude and pseudo-depth. c, f, Along-density zonal mean radiocarbon content (Δ¹⁴C) as a function of latitude and pseudo-depth. Notice that the colour scales differ from those in Fig. 3. Panels with a pseudo-depth y axis have density contoured in black every 0.1 kg m⁻³ for γ ≥ 27.5 kg m⁻³. In the western Atlantic (a–c), white curves depict the local northward–southward and diabatic–adiabatic transition levels inferred from the incrop area distribution, as in Fig. 3. In the eastern Atlantic (d–f), whose abyss is not fed from the south but instead through ridge gaps in the vicinity of the Equator, white curves correspond to peak and weak incrop density surfaces based on the total sub-basin incrop profile. Sub-basin masks are shown in Extended Data Fig. 1b.