Ocean Drilling Program (ODP) Site 899, on the Iberia Abyssal Plain, was drilled during Leg 149, an east-west transect of sites, to examine the nature of the ocean/continent transition on the Iberia Margin. Sawyer, Whitmarsh, Klaus, et al., (1994) record shipboard observations made during Leg 149; this volume summarizes the postcruise results and conclusions drawn from the work. Three serpentinite-breccia units, pre-Late Cretaceous to late Barremian in age, form part of Subunit IVA (369.9-484.2 m below seafloor [mbsf]) in Hole 899B, one approximately 95 m thick, and two less than 20 m thick. This account draws on the shipboard description of the breccias (Shipboard Scientific Party, 1994) and discusses several possible origins for the units. We conclude from observational and chemical evidence that the breccias formed as large landslide deposits, probably derived from unstable scarps exposed during extensional faulting during the Early Cretaceous opening of the north Atlantic.