A jetty is a structure, usually of wood or stone, built out onto water. The term can refer to a built structure at the entrance to a harbor, or running out into the sea or into a lake, to defend the shore from the action of the waves; a structure built into a river to divert the current in order to prevent erosion or to shape a channel by controlling the deposit of sediment; an outwork of piles or timbers protecting a pier; or the lightly constructed and projecting portion of a more heavily constructed wharf or landing pier. Thus a maritime jetty usually functions as a breakwater, and freshwater jetties are usually structures built parallel to the bank at or near the mouth of a river to control the shape of the channel. The most famous example of this latter use is the series of jetties constructed by James Buchanan Eads in 1879 to create a dependably navigable channel from New Orleans to the Gulf of Mexico. Jetties that serve as breakwaters are usually built in a straight line and more or less perpendicular to the shore. Hence, the name of Robert Smithson’s earthwork Spiral Jetty on the Great Salt Lake must be intended to be paradoxical. However, the matter is really not this simple. Jetty comes from the Old French jetée, which describes the action of throwing something outward. There are a lot of names for structures built out over water. And they are so often used interchangeably; it is a question whether jetty, groyne or groin, mole, wharf, quay, pier, breakwater, and seawall are synonyms, words for distinct structures, or for similar structures with different uses, or whether they have simply meant different things in different times and places. Here’s a Cape Cod jetty from Conrad Aiken’s poem “Letter to Li Po”: “The tide/scales with moon-silver, ﬂoods the marsh, fulﬁls/Payne Creek and Quivett Creek, rises to lift/the ﬁshing boats against a jetty wall.” And here is a North Carolina jetty from Bland Simpson’s Into the Sound Country that is almost a still-life: “Not far from Little River jetty stood a curved-top, rural mailbox on a post in the dunes, a sandy park bench nearby, aimed out to sea.” North Carolina also produced the 1950s and 60s band Homer Briarhopper and the Jetty-jumpers.