In the context of coastal geomorphology and oceanography, which depositional feature forms when longshore drift transports sand across the mouth of a bay, eventually sealing it off entirely from the open sea to create a coastal lagoon?

💡 Solution & Explanation

A baymouth bar is a depositional ridge of sand that completely crosses the mouth of a bay, isolating the inner water body as a coastal lagoon. A spit is a linear ridge of sediment attached to the mainland at one end and terminating in open water. A tombolo is a sand ridge that connects an offshore island or stack to the mainland. Barrier islands are broad, offshore sand ridges running parallel to the coast.