“…The Moho corresponds to a compressional wave velocity increase from ~6.7 km/s to between 7.6 and 8.6 km/s, typically at ~7 km beneath the oceans. Since the work of Adams and Coker (1906), Adams and Williamson (1923), and Wrinch and Jeffreys (1923), the Moho has generally been regarded as the boundary between crust and mantle; however, an al-IODP Proceedings 2 V o l u m e 3 6 0 ternative model, that the Moho is a hydration front in the mantle (Hess, 1960(Hess, , 1962, has recently gained credence upon the discovery of abundant partially serpentinized peridotite on the seafloor and on the walls of fracture zones. One such location is Atlantis Bank, an 11-13 My old elevated oceanic core complex massif adjacent to the Atlantis II Transform on the Southwest Indian Ridge (SWIR).…”