Explore Geology
geology fieldnotes title

Cumberland Island

National Seashore

Georgia

cover of park brochure

park geology subheading
Beach photo at Cumberland Island Seashore
Cumberland Island National Seashore, Georgia

Forests so quiet that you can hear yourself breathe, sunlight filtered and diffused through overarching trees and vines, sounds of small animals scurrying in the underbrush, the gentle splash of water moving through the salt marsh, the courting bellow of the alligator, blinding light on water and sand as you emerge from the shadows of the live oak forest, a standing row of slave cabin chimneys, fallow gardens, and crumbling walls of mansions from bygone eras. This is Cumberland Island, Georgia's largest and southernmost barrier island and today a national seashore.

The word "seashore" is misleading, for Cumberland Island is a complex ecological system of interdependent animal and plant communities. Each lends itself to the preservation of the other. A system of foredunes protects the interdune meadow and shrub thickets. A canopy of live oak trees stretches out just beyond the back dunes that provide protection from the salt spray. In the central and northern sections of the island, pine trees tower over mixed hardwood forests. On the western side of the island, saltwater marshes pulse with the tidal flow. Because the previous owners maintained Cumberland Island in its natural state, nature still reigns on this land that bears the imprint of humankind.

Saltwater Marshes
Approaching the island from St. Marys, Georgia, the marshes first come into view. When the tide is out, the marsh appears like a broad plain of tall grasses intricately interwoven with tidal creeks. saltwater marshes Closer examination reveals an array of birds wading through the grass or feeding at the banks of the creeks. Fiddler crabs scurry across the mud flats and eat decaying vegetation and other organic material. Raccoons and other animals come down from the uplands to feed on crabs and to search for shellfish.

When the tide is in, the tops of the grasses sway with the current, making it hard to distinguish between grass and water, the color of one intensifying the color of the other. These tides play a vital role in the life of the marsh, for on their flood cycle they bring the microscopic organisms that many creatures need for nourishment and the water that they need from which to draw oxygen. On their ebb, the tides flush the silt and debris washed into the marsh from the inland rivers out to sea. The marshes buffer the landward side of the island from the twice daily influx of tidal flow and absorb some of the impact of storms. Marshes possess quiet, changeable beauty, and yet they are the most productive land acre per acre on this planet. With their wealth of nutrients, marshlands support large populations of fish, shellfish, plants, and birdlife. They also act as nurseries. Here in the grasses and shallow waters, the young of many species begin their lives protected from predators.

Maritime Forests
As the marshlands become higher and drier, washed only at extremely high tides, the salt tolerant communities give way to freshwater plants and, then, finally, to trees. The most striking maritime forestsfeature of the live oak forest is the solitude. Even the air seems to move noiselessly above the tops of the trees' arching branches. The sounds of an ordinary rainshower are muted by the dense canopy of leaves and vines. Cradled in the branches, Resurrection ferns spring up with this life giving moisture. Draping Spanish moss lends a touch of the exotic as it sways in the breeze. The vivid plumage of painted buntings, summer tanagers, cardinals, and pileated woodpeckers add a splash of color to the somber hues of the forest while the clear notes of yellow-throated warblers and Carolina wrens punctuate the stillness.

Deeper in the forest's shadows at the midday, or in the interdune meadows at dusk, you may catch a fleeting image of the island's numerous whitetail deer. Raccoons, the masked bandits of the forest, are frequently seen as they tour the island on their nightly forays. You may come across a shy and newly arrived resident, the armadillo, first seen on Cumberland in 1974. Sloughs mark the eastern edge of the forest, where trees give way to the realm of dunes and beach. Farther inland, fresh water ponds appear like jewels. Here on a warm spring night you can hear the booming of the bull alligator as it goes through its courtship rites. Rainfall sustains the ponds and in turn the wildlife that are drawn to them, adding yet another dimension to the island.

Beach
Emerging from the darkness of the forest to the brightness of the beach, you momentarily lose your sight, so sudden is the change. On the beach the waters rise and fall twice daily, washing beachback and forth across the sand, shaping, and rearranging. The wind, too, plays a role in this process. Barrier islands appear to be permanent, but actually they are continually in the process of change. In some areas on Cumberland Island, you may notice the dunes covering the shrubs and trees in their path. The plants that grow on the dunes are the stabilizing element. Their root systems are fragile and are affected by the impact of humans and animals. Overgrazing by the island's feral horses may impair the ability of some grasses to reproduce.

Here the shorebirds are given to the spirit of movement. Sandpipers dance before the rhythmic advance and retreat of the water, and gulls soar on the ocean breeze. An osprey may dive into a wave before your eyes and a few seconds later emerge with a mullet in its talons. Loggerhead turtles, ancient reptiles of the sea, lumber ashore on Cumberland's deserted beaches at night. Guided by instinct, they lay their eggs and then return to the sea. Hatchlings emerge about 60 days later and scurry for the protection of the surf. Today tracks of humans, birds, and other animals mark the beach. Tomorrow they will have been swept away, and the beach will take on new configurations.


For thousands of years people have lived on Cumberland Island, but never in such numbers as to permanently alter the character of the landscape.
  • Piles of shells, called middens, provide us with clues to the lives of the Indians who left them.

  • An occasional pot shard indicates that Spanish soldiers and missionaries were here in the mid 1500s.

  • No signs remain of Fort William and Fort St. Andrews, built to protect British interests. Revolutionary War hero General Nathanael Greene purchased land on Cumberland Island in 1783. His widow, Catherine Greene, constructed a four story tabby home that she named Dungeness.

  • In the 1890s, the Settlement was established for black workers. The First African Baptist Church, established in 1893 and rebuilt in the 1930s, is one of the few remaining structures of this community.

  • Thomas Carnegie, brother and partner of steel magnate Andrew Carnegie, began building, with his wife Lucy, on Dungeness's foundations in 1884. The ruins of this mansion remain today.

  • Plum Orchard, an 1898 Georgian Revival style mansion built for son, George, and his wife, Plum HouseMargaret Thaw, was donated to the National Park Foundation by Carnegie family members in 1971. Their contribution as well as funds from supporting foundations, helped win Congressional approval for establishing Cumberland Island National Seashore.


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 geology 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.

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/cuis/index.cfm   I  Email: Webmaster
This site is best viewed in Internet Explorer 6.0 or Netscape 7.0