Fort Frederica National Monument: Geology and Geodiversity

Fort Frederica National Monument. NPS.

Geodiversity is the full variety of a park's rocks, minerals, sediments, fossils, landforms, soils and the processes that shape them. The Park Service's Geodiversity Atlas, from its Geologic Resources Inventory, supports education, geoconservation and managing the living and non-living parts of each ecosystem together.

The monument

• Where: St. Simons Island on the Georgia coast, about 19 km (12 mi) northeast of Brunswick, in Glynn County.
• Authorized: May 26, 1936, to preserve and interpret colonial Fort Frederica. After a 2019 expansion it covers about 123 hectares (305 acres) in two units: the main fort on the Frederica River, and the Battle of Bloody Marsh site about 8 km (5 mi) south.
• History: General James Edward Oglethorpe founded Frederica in 1736 as a British fort and town, to claim the region and guard the new colony's southern edge against the Spanish in Florida. Two battles were fought on the island in 1742; the British victory at Bloody Marsh ended Spain's claim to Georgia and the Carolinas.

The ground beneath

Fort Frederica lies in the Sea Island Section of the Atlantic Coastal Plain.

• Marine terraces: the region is built of Quaternary terraces recording old shorelines. They step down in age and elevation toward the Atlantic, formed from the Pleistocene to today as sea level rose and fell with the ice ages.
• The park's two deposits:
• 1. Pleistocene Sandy Bluff Shoreline Complex — loose beach sand;
  2. Holocene shoreline complex — loose, fine-grained sediment, including salt-marsh mud churned by burrowing animals and beach to nearshore sand.

The fort on the Frederica River. NPS.

Maps and reports

The Geologic Resources Inventory makes digital geologic maps and reports for more than 270 natural resource parks. Fort Frederica's products — scoping summaries, GIS maps, reports, posters and project listings — are on the NPS DataStore. A Soil Resources Inventory has been completed (DataStore).

More: Fort Frederica, the Park Service's regional geology pages, and the Georgia Geologic Survey.

Sources

Based on "NPS Geodiversity Atlas—Fort Frederica National Monument, Georgia," National Park Service, citing the National Park Service (2016) and Scott and others (1986); a work of the United States government in the public domain.