How is a Ria coast formed?

Answer 1

It is formed when lateral erosion erodes the coast due to cavitation, abrasion, attrition and hydraulic action.The ria coast A ria is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Typically, rias have a dendritic, treelike outline although they can be straight and without significant branches. This pattern is inherited from the dendritic drainage pattern of the flooded river valley. The drowning of river valleys along a stretch of coast and formation of rias results in an extremely irregular and indented coastline. Often, there are islands, which are summits of partly submerged, pre-existing hill peaks. A ria coast is a coastline having several parallel rias separated by prominent ridges, extending a distance inland.[1][2][3] The sea level change that caused the submergence of a river valley may be either eustatic(where global sea levels rise), or isostatic (where the local land sinks). The result is often a very large estuary at the mouth of a relatively insignificant river (or else sediments would quickly fill the ria). The Kingsbridge Estuary in Devon, England, is an extreme example of a ria forming an estuary disproportionate to the size of its river; no significant river flows into it at all, only a number of small streams.

Answer 2

A Ria coast is formed through the combination of rising sea levels and erosion of coastal areas by rivers and glaciers. As sea levels rise, valleys are flooded, creating long, narrow inlets that are characteristic of Ria coasts. The remaining landforms become rugged and irregular due to erosion, leading to the formation of steep cliffs and rocky outcrops.