Breakwater: a structure, usually detached from the shoreline, protecting a shore area, harbor, anchorage or basin from waves.

Erosion: the wearing away of land by the action of natural forces. On a beach, the carrying away of beach material by wave action, littoral currents or wind.

Groin: a structure built (usually perpendicular to the shoreline) to trap littoral drift or retard erosion of the shore. Groins on the western shoreline of Lake Michigan are usually placed south of beaches to retain sand drifting from the north.

Jetty: on an open coast, a structure extending into a body of water, and designed to prevent build-up of littoral materials in a channel. Jetties are built at the mouth of harbors or other navigable waterways.

Littoral Drift: the movement of sediments, caused by wave action, along the coastline. On the western shoreline of Lake Michigan, littoral drift carries sediments from the north to the south.

Perched Beach: a sand beach retained above the otherwise normal profile level by an off-shore submerged dike or bulkhead. Perched beaches are constructed where a beach is desired but the water depth is too deep and profile too steep to fill with sand. Examples are the beaches south of Fullerton Avenue.

Rebuild: either dismantle the existing structure and recreate or, if infeasible or impractical, reconstruct at a point further out into the lake (15 feet to 20 feet out).

Repair: selective removal of pieces of a structure and replacement or partial reconstruction.

Revetment: any hardened shoreline to protect softer land behind it. Revetments may be constructed of steel sheet piling, stone, concrete, wood or a combination of these.

Rubble: rough irregular fragments of broken rock.

Sheetpile: interlocking steel piles driven vertically through the sand and into harder clay lake bottom.

Step-Stone: large stone or concrete blocks placed or stacked along the shoreline. Provides convenient pedestrian access.

Submerged Bulkhead: an underwater structure designed to retain sand or landfill to the shore side. The lake bottom on the lake side is deeper. Submerged bulkheads are used to create plateaus or perched beaches.