A delta is formed when a river carries sediment to the coast and deposits it beyond the river's mouth. Tidal currents and waves re-work the newly deposited sediments, affecting the shape and form of the resulting feature.
At wave-dominant deltas, waves sort and redistribute sediments delivered to the coast by rivers and remold them into shoreline features such as beaches, barriers, and spits. The morphology of the resulting delta reflects the balance between sediment supply and the rate of wave reworking and redistribution. The northern coast of Alaska is an example of a deltaic coast heavily impacted by wave energy.