<P> A ria ( / riːə / or / riə / ) 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 naturally - occurring islands , which are summits of partly submerged , preexisting hill peaks . ( Islands may also be artificial , such as those constructed for the Chesapeake Bay Bridge - Tunnel . ) </P>
<P> A ria ( / riːə / or / riə / ) 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 naturally - occurring islands , which are summits of partly submerged , preexisting hill peaks . ( Islands may also be artificial , such as those constructed for the Chesapeake Bay Bridge - Tunnel . ) </P>
drowned valley forming an inlet of the sea
drowned valley forming an inlet of the sea
ria
ria