Britannica Sources used in this answer

Why does surf action remove fine sediment from some continental shelves?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

continental shelf The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin.

Surf action removes fine sediment from continental shelves through a process called winnowing. As a high-energy force, the surf zone erodes and reworks the seafloor as it passes over it. This action effectively separates materials by size, lifting and carrying away finer-than-sand-sized particles while leaving behind coarser material.1

Once these fine-grained materials are winnowed out, they are typically transported away from the shelf area. Depending on the specific environment, this sediment may be deposited back into estuaries or carried across the shelf by advective processes to deeper waters beyond the shelf break. Ultimately, these fine particles may settle through the water column as pelagic sediment, contributing to the formation of the continental rise.12