Because of this, sediment in the surf zone is transported along the beach in a zig-zag pattern. It is referred to as a longshore current . Ocean currents benefit plant and animal life by bringing in nutrients and oxygen-rich water, and by carrying away wastes. Waves can force water into cracks in rocks along the shoreline, causing water pressure to build up in the cracks. Over time the cracks become larger and the pressure breaks the rocks.
Waves can deposit sediment, in addition to eroding it.
Sediment that is eroded in one area will be deposited in another area. Shoreline Erosion Man-made structures are sometimes built along the shoreline to try to reduce or prevent erosion. Seawalls may be built along the beach to prevent the waves from eroding the shoreline, and to protect homes or other structures built along an eroding beach. Sea wall attempting to prevent coastal erosion, south end of St. Simons Island, GA Groins and jetties are built perpendicular to the coastline in an attempt to trap some of the sand being carried by the longshore current. Sand is deposited and the beach is built outwards on the upcurrent side, but on the downcurrent side of the groin or jetty, erosion occurs.