Looking at the surface of a beach is like reading a history book. The physical processes that shape the beach leave behind all sorts of evidence of their presence.
Currents, the back and forth of the wave “swash” (the water that washes ashore after a wave has broken), wind, and, of course, hurricanes all leave unique and easily identifiable marks.
Those living in the New York-metro area have access to both naturally occurring beaches (including much of the Fire Island National Seashore, some outer Long Island beaches, and Sandy Hook National Seashore in New Jersey) as well as “nourished” — meaning artificially expanded — beaches such as Coney Island, the Rockaways, most of the beaches of Northern New Jersey and many of the beaches on the South Shore of Long Island. When a beach is “nourished,” it means that machinery pumps new sand onto the beach’s surface from the seabed.
Click the photos below to learn about how Irene changed the local beach landscape:
Sandy beaches are often flatter and wider after a storm. Broadening is a way that the beach "saves" itself because the flattening allows the waves to expend their energy over a broadened zone and thus reduce erosion.
Sometimes the waves penetrate through gaps in the dune line and carry sand onto the land behind the shoreline. As a result, the elevation of the island is raised, as happened on Fire Island during the storm.
Sometimes waves coming from a certain direction will add sand or gravel to a beach. This happened during Irene due to winds from the southwest.
AP/J Pat Carter
After a storm, an erosion scarp might appear on the upper beach. A scarp is a small cliff in the sand or sand dunes, usually 1 to 3 feet in height, but sometimes as much as 10 feet high. In 2002, former New Jersey Governor James McGreevey broke his leg after falling off a scarp during a nighttime walk with his wife. This scarp appeared after the hurricane on Long Beach Island in Long Beach Township, N.J.
On developed shorelines the unmistakeable evidence of a storm is the debris on the beach. In a moderate storm, wooden dune walkovers and pier fragments are common. In a big one like Irene, houses collapsed on the beach as in Connecticut and highway fragments on the beach as in North Carolina attest to the past event.
It is common to see marks on the posts supporting houses that indicate where the beach level was before the storm carried sand away. This photo of a collapsed beach house in East Haven, Conn. was taken on Monday, Aug. 29.
MetroFocus is made possible by James and Merryl Tisch, the Cheryl and Philip Milstein Family, Josh and Judy Weston, Jody and John Arnhold, The Shelley & Donald Rubin Foundation, Jean and Ralph Baruch, and The Nissan Foundation. Corporate funding is provided by Mutual of America.