accretion deposit

Coral islands created by accretion have developed from rubbly reef rock broken off from the reef by storms and waves and mixed with finer reef detritus. The exceptional conditions of cyclonic storms are sometimes sufficient to create reef-top shoals in a single event. Other material accumulates by more regular…

…referred to as (1) lateral accretion deposits, which develop within the channel itself as the river migrates back and forth across the valley bottom, and (2) vertical accretion deposits, which accumulate on the floodplain surface when the river overflows its channel banks.