Gulf Islands National Seashore: Geologic resources inventory report
Schupp CA. 2019. Gulf Islands National Seashore: Geologic resources inventory report. Natural Resource Report. NPS/NRSS/GRD/NRR—2019/1986. National Park Service. Fort Collins, Colorado
Gulf Islands National Seashore (referred to as the “park” throughout this report) is located within the Coastal Plain physiographic province, which extends for more than 3,500 km (2,200 mi) from Cape Cod, Massachusetts, to the Mexican border. The Coastal Plain physiographic province consists of seaward-sloping lowlands and the submerged continental shelf along the Atlantic Ocean and Gulf of Mexico. The park is in the portion of the province known as the East Gulf Coastal Plain. The park encompasses 13 units that consist of barrier islands and mainland areas along the coasts of Mississippi and Florida (National Park Service [NPS] 2018). The park’s purpose is to preserve and interpret an interconnected system of coastal defense fortifications, barrier islands, wilderness, and coastal and marine ecosystems, while providing for public use and enjoyment (NPS 2016a). This report describes the geologic connection to the park’s fundamental resources and values, which were identified in the park’s foundation document (NPS 2016a) and include terrestrial and marine ecosystems, barrier islands, and wilderness. In addition, many of the planning issues and concerns raised in the park’s general management plan (NPS 2014) have geologic considerations that are discussed in this report; these include preserving coastal ecosystems, storm recovery and sustainability, oil and gas development, the Deepwater Horizon oil spill, and climate change. The park hosts a diversity of coastal habitats such as forests, beaches and washover fans, seagrass beds, interior dunes, coastal marshes, interior brackish ponds and creeks, and interior sand flats. These habitats support aquatic and terrestrial plant and animal life, including federally protected species, migratory birds, and turtle nesting sites. The park is relatively young, geologically speaking. The barrier islands were formed within the last 5,000 years. They sit atop sedimentary fluvial, estuarine, and nearshore marine strata deposited during sea level oscillations that took place during the Pliocene, Pleistocene, and Holocene Epochs—a timespan that covers the past 5.3 million years. The modern islands are shaped by the region’s geologic framework and bathymetry, as well as interactions with coastal processes—such as storms, waves, tides, sediment transport, inlet dynamics, and sea level change—and anthropogenic activities—such as inlet dredging and shoreline engineering—that rework the Quaternary (Pleistocene and Holocene) sediments. This report is supported by two GRI GIS data sets (gifl_geology.mxd and gims_geology.mxd) that provide coverage of the Florida and Mississippi portions of the park, excluding the mainland areas; that is, Santa Rosa Island and Perdido Key in Florida and Cat Island, East and West Ship Islands, Horn Island, and Petit Bois Island in Mississippi. Mapping for Sand Island is not included in the GRI GIS data, but figure 7 of this report illustrates ecological habitats and geomorphic features (marsh shrubland, beach dune herbland, water, and bare sand) that make up Sand Island. In addition, the GRI team produced component maps for Cat Island (cati_geology.mxd), Horn Island (hrni_geology. mxd), Petit Bois Island (pebo_geology.mxd), and Ship Island (ship_geology.mxd); these were derived from gims_geology.mxd (the digital geomorphic map for the Mississippi portions of the park). The GRI team created the GRI GIS data using US Geological Survey (USGS) open-file reports. The GRI GIS data delineate the locations of 19 geomorphic map units.
- Type
- Published Report
- Authors
- Schupp, Courtney
- Date of Issue
- 2019-08
- Publisher
- National Park Service
- Units
- GRD , GRI , GUIS , GULN , NRSS , SER
- Keywords
- Abandoned Mineral Lands, Coastal Engineering and Beach Nourishment, Coastal Erosion, Coastal Resource Management and Planning, Coastal Vulnerability and Sea Level Rise, Decline of Seagrass Beds, Dredging of Inlets, Energy Development, Estuarine Sediments, Florida, Geologic Features, Geologic History, Geologic Processes, Geologic Resource Management Issues, Geologic Resources Division, Geologic Resources Inventory, Geomorphic Map Units, GRD, GRI, Groundwater, GUIS, Gulf Islands National Seashore, Hurricane Impacts and Human Responses, Impacts to Wetlands, Inlets, Map Unit Properties Table, Map Units, Mississippi, National Park Service, Nearshore Substrate and Benthic Habitat, NPS, Oceanographic Conditions, Overwash and Island Migration, Paleontological Resource Inventory and Protection, Paleontological Resources, Resource Management, Seagrass, Sediment Budget Data Needs, Sediment Transport Processes, Visitor Safety, Visitor Use Impacts, Water Quality, Wetlands
- Subjects
- Ecological Framework: Geology and Soils | Geomorphology | Coastal/Oceanographic Features and Processes , Ecological Framework: Geology and Soils | Paleontology | Paleontology