In geology, accretion refers to the process by which material is added to a tectonic plate at convergent boundaries. This material can include sediment, volcanic arcs, and other fragments of crust that are scraped off a subducting plate and attached to the overriding plate, forming an accretionary wedge. Accretion plays a significant role in the growth of continental crust and the formation of mountain ranges.
Source Ballard, Robert D. (1988). Exploring our living planet. National Geographic Book Service., National Geographic Society (U.S.) (Rev. ed.). Washington, D.C.: National Geographic Society. ISBN 0-87044-760-2. OCLC 18325626