fluvial (river) sediment, material from cliff erosion and mass movement, material transported by ice, beach nourishment, destructive waves or tides depositing material
open systems receive inputs of materials and energy from other systems outside of their boundaries and lose outputs of materials and energy to other systems
coasts operate on a range of spatial cells (cells within cells) and temporal scales - sediment moves within the cell but doesn't transfer from one sell to another so is considered a closed system