• Miles of uncrowded white sandy beaches extend to the horizon, separating the clear blue ocean and undulating grass-covered dunes.

    Fire Island

    National Seashore New York

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  • More Park Facilities Reopen During May 2013

    Watch Hill and Sailors Haven marinas open May 10. Limited ferry service from Sayville to Sailors Haven resumes May 13 and ferries from Patchogue to Watch Hill start on May 18. Remaining park facilities to reopen by May 25, 2013. More »

Beaches

White sand beach overwashed with reddish garnet sand.
While Fire Island's white sandy beaches consist mainly of quartz, you may occasionally see layers of a fine reddish-black material: tiny grains of pulverized garnet and magnetite.  See more below!
 
Watch Hill Beach in summer.

The summer beach is typically wider and flatter than the beach in winter.

Fire Island's beaches are composed mainly of white quartz sand of varying grain size. Occasional layers of heavy mineral sands-which include grains of garnet and magnetite-appear as colored bands among the predominantly white sediment. There are also small amounts of feldspar, tourmaline, mica and other minerals. Occasionally, you will find pebbles or fragments of shell on the beach.

The particle size of beach sand is layered, depending on the energy of the depositing waves and wind.

 
Exposed black peat is uncovered on ocean beach.

Hard, black deposits of peat are occasionally uncovered on Fire Island's Atlantic Ocean beach.

The size and shape of the beach is always changing. While sediment is constantly being moved more or less perpendicular to or from shoreline by tidal and wave action, the predominant net movement of sediment along Fire Island's coast is parallel with the shore through the effects of longshore currents. The movement is called longshore sediment transport and its rate is dependent on wave energy and the angle at which waves strike the coast.

 
Footprint in reddish sand.
Take a closer look at what's under your feet on Fire Island's sandy beach.
 

What's Fire Island's sandy beach made of?

Long Island is composed of material left by glaciers thousands of years ago. The South Shore is composed of the finer glacial sediments, reworked by waves and currents to form the coastline we see today.

 
Close-up of sand grains
While Fire Island's beaches are comprised mostly of white quartz sand, you'll see grains of red garnet and black magnetite, and small amounts of feldspar, tourmaline, mica and shell fragments if you look closely at the darker layers of sand. 
NPS Photo/Coffey
 
Coastal Geology Multimedia program cover.

NPS Natural Resource Program Center

For More Information

Learn more about Coastal Geology in our National Parks:

 

Did You Know?

Seal on beach in winter.

Seals occasionally bask on Fire Island beaches in winter. Enjoy watching them from a safe distance. Remember to give these wild mammals plenty of room to retreat if you encounter one during your winter hike! More...