Sediments that accumulate along sea or lake shores. One type of beach occurs as a sediment strip bordering a rocky or cliffy coast. A second type is the outer margin of a marine plain. The third type consists of narrow sediment barriers stretching for dozens or even hundreds of miles parallel to the general direction of the coast. These barriers separate lagoons from the open sea and generally are dissected by tidal inlets. Certain sediment forelands, such as spits, points, and tombolos (which connect an island with a mainland), occasionally are called beaches.