Explore Geology
geology fieldnotes title

Gulf Islands

National Seashore

Mississippi / Florida

cover of park brochure

park geology subheading
close up photo of vegetation on the shore
Gulf Island National Seashore, Mississippi / Forida

Relaxation and recreation.
Whether you're spending an afternoon on the beach or a vacation at one of the campgrounds, these are the gifts offered to you by Gulf Islands National Seashore. Clear blue waters, gentle sloping beaches, coastal marshes, and human history present a backdrop for taking life easy. Here in the northeastern Gulf of Mexico, Congress has set aside a few of the barrier islands for recreation and for their natural and historical resources. The park stretches from West Ship Island in Mississippi 240 kilometers (150 miles) east to the far end of Santa Rosa Island in Florida. None of the park is located in the finger of Alabama that juts between the other two states.

Islands alone do not constitute the national seashore. A few areas on the mainland have also been included. Here you can find

  • old forts;
  • an experimental tree farm begun by John Quincy Adams;
  • archeological traces of the earliest inhabitants; and
  • the plants and wildlife of the estuaries, those arms of the sea where saltwater and freshwater mix.

The barrier islands, however, are the glue that holds this mosaic of land and water together. The source of the brilliant white sand is rock material from the upland areas to the north. Over millenniums, streams and rivers moved the weathered remains of these rocks down to the sea. There are several theories as to how the islands were formed from this sand. All theories involve wave and wind action and fluctuating sea levels shaping the barrier islands that lie parallel to the gulf coast.

These islands are ever-changing, moving constantly to the west. Littoral currents wear away the eastern ends and build up the western ends. Violent storms cause overwash that rearranges large amounts of sand. Constant winds, on a smaller scale, shift and build dunes. Change by the winds is slowed only by the protective covering of grasses and other vegetation growing on the dune line nearest the gulf. The elaborate stem and root system of the sea oat, in particular, is vital to the protection and stabilization of barrier islands. So important in fact, that the picking or disturbing of sea oats and other vegetation is strictly prohibited. Barrier islands are just that, "barriers." They effectively reduce the destructive force of violent storms before reaching the mainland. They provide quiet waters behind them for valuable marine life, and their long stretches of beach invite you to swim, walk, surf, fish, and just relax.

When Europeans first arrived on these shores in the early 1500s, they reported finding a rich native American culture. At Naval Live Oaks in Florida an unusually rich collection of Indian village sites, middens (trash piles), and other remains have been the focus of archeological investigations that continue to add to our understanding of earlier inhabitants and to trace human history in the area. Today the historic sites, whether they be village locations, ruins of 19th-century forts, or concrete gun emplacements, are protected on the barrier islands and the nearby mainland.

Discovery of this part of the New World was followed by a struggle between colonial powers for its control. Both Spain, in the mid-1500s, and France, about 1700, attempted to establish settlements in present-day Mississippi. The rivalry came to a peak in the early 1800s when the young United States cast covetous eyes on this territory. By 1821 the United States had acquired the last of West Florida and the colonial era ended.

The next year the United States began plans to develop Pensacola into a major naval base with protecting fortifications. The only action the forts saw, however, came during the Civil War. Beginning in the last years of the 19th century, fortifications continued to be developed and updated along the coast. They were manned up to the end of World War II, when the concept of coastal fortifications became obsolete.

This then is Gulf Islands National Seashore, a park rich in cultural and natural history opportunities. Whatever you do or however long you stay, we hope that you enjoy your visit.

The Life of a Barrier Island
Barrier islands are special places. They appear permanant and static but in fact are continually changing, moving parallel to the mainland and toward or away from it. They buffer the mainland from storms, but storms may cause a particular island to disappear or split in two. Or storms may push a dune line clear across an island as Hurricane Fredric did in 1979 on parts of Santa Rosa Island.

Despite all these transitory qualities, life grabs hold on these islands as if it meant to hang on forever. Salt is one of several factors determining the kind and abundance of plant life. Near the gulf, plants, such as the sea oats, which are tolerant of high salt levels can grow. Behind the primary dune, shrubs and some trees can be found, but they never grow much higher than the dunes that protect them from the salt spray. Farther back, freshwater collects in marshes among old dunes and supplies trees with water.

Animal life on these barrier islands, too, is limited by the plant life, which provides food and protection. This is a special little world extraordinarily affected by the whims of nature. Behind barrier islands the waters of the sound and bayou are less salty. And nutrients washed down from the mainland support a rich marine life. Here shrimp and fishes valuable to commercial fishermen move through many of their life cycles. Protection is the key word. The barrier islands give shelter to rich plant and animal communities on the islands, in the sound and bayou, and on the mainland itself.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A general photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

selected links subheading

NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

Currently, we do not have a listing for any park-specific geology education programs or activities.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://www.nature.nps.gov/Geology/parks/guis/index.cfm   I  Email: Webmaster
This site is best viewed in Internet Explorer 6.0 or Netscape 7.0