South Carolina’s coastline contains many beautiful beaches, salt marshes and estuaries, as well as natural ports such as Georgetown and Charleston. An unusual feature of the coastal plain is a large number of Carolina bays, the origins of which are uncertain. The bays tend to be oval, lining up in a northwest to southeast orientation. The terrain is flat and the soil is composed entirely of recent sediments such as sand, silt, and clay. Areas with better drainage make excellent farmland, though some land is swampy.