An accretionary prism (also called accretionary wedge) is a sedimentary body formed by which ocean floor sediments and trench-fill sediments provided from the land accrete to the landward slope of trench by off-scraping accretion and underplating accretion. Oceanic plate subduction is responsible for such accretion. Slices (thrust sheets) pile next to one another with reverse faults (thrust faults). They are characterized by inward younging in each sheet and overall outward younging.