St. Catherines Island is a barrier island on the Georgia coast. The island trends nearly north-south, and is about 16 kilometers (10 miles) long and 5 kilometers (3.1 miles) wide; it is located between latitudes of 31° 42' and 31° 33.5' N. St. Catherines and most other Georgia barrier islands are composed of sediments formed by two shorelines separated in geologic time: the Silver Bluff shoreline, which was during the Pleistocene Epoch, and the modern one. These overlapping shorelines partially control the distribution of modern ecosystems on the island.
Ecosystems on St. Catherines include salt marshes, maritime forests, grasslands, beaches, and freshwater ponds. The climate is temperate to subtropical, with temperatures ranging from an average high of 90°F in the summer to 50° F in the winter, and rarely goes below freezing. Rainfall is about 50 inches/year, with most precipitation during hurricane season (May-September). Hurricanes, however, rarely affect the Georgia coast, with the worst recorded one having been in 1898.
Humans have interacted with St. Catherines ecosystems for a minimum of 4,000 years, starting with Native Americans (the Guale people). The Guale were later succeeded by the Spanish (16th-18th centuries), who established a mission (Mission Santa Catalina de Guale) on the island; the present name “St. Catherines” is the Anglicized version of Santa Catalina. The British took St. Catherines from the Spanish in the early 18th century. Americans occupied the island in the later part of the 18th century. Enslaved Africans were brought to the island during the 18th and 19th centuries as laborers for plantations, and inland ecosystems of St. Catherines were altered considerably by this agriculture.
American businessman Edward J. Noble, who bought the island in 1943, decided to use St. Catherines Island to encourage conservation efforts and scientific research; this research later included archaeology, ecology, geology, and wildlife biology. In 1981, the title of the island was transferred to the St. Catherines Island Foundation, which still supports scientific research and maintains research facilities on the island.