Figure F21. Latitudinal transect of Ca mass accumulation rate (MARs) for three time slices: early Oligocene (25–34 Ma), middle Eocene (38–45 Ma), and early Eocene (50–55 Ma). Ca MAR almost exclusively results from the deposition of CaCO₃. The early Oligocene pattern of Ca MAR is the only one that resembles the Neogene in both shape and magnitude. CaCO₃ is essentially absent from middle Eocene sediments along the 56-Ma transect but is present intermittently at the southern end of the transect. The early Eocene Ca MAR is about half of modern flux, and curiously, equatorial Ca MAR is significantly less than the off-axis flux.