Broken Ridge represents a fragment of the oceanic Kerguelen-Heard platform, constructed at high southern latitudes in the middle Cretaceous and rifted apart during the middle Eocene (43-45 Ma). The approximately 1400-m section of prerift sediments on Broken Ridge preserves a polarity sequence that spans the middle Eocene to Upper Cretaceous (Chrons Cl 8/C20 to C34), including a 500-m continuous...