Since 2007, the USGS (with NPS and USACE) has been mapping the seafloor and substrate around the Mississippi barrier islands to characterize the near-surface stratigraphy and identify the influence it has on island evolution and fate.

This research is part of the Geologic and Morphologic Evolution of Coastal Margins project.
Coastal Mississippi is protected by a series of barrier islands (Petit Bois, Horn, East Ship, West Ship, and Cat) that comprise the Gulf Islands National Seashore (GUIS). The islands support an ecologically diverse shoreline that provides habitat for wildlife including migratory birds and endangered animals. The majority of GUIS is submerged, and aquatic environments include dynamic tidal inlets, ebb-tide deltas, sandy shorelines, and seagrass beds. The islands are in a state of decline, with land areas severely reduced during the past century by storms, sea-level rise, and anthropogenic alteration. Since the mid-1800s up to 64 percent of GUIS surface area has been lost. Heavy damage is inflicted on the islands by frequent hurricane events, including Hurricane Katrina in 2005, which passed by as a Category 3 storm and battered the islands with winds of more than 160 kilometers per hour and a storm surge up to 9 meters.
Since 2007, the USGS, in collaboration with the National Park Service, has been mapping the seafloor and substrate around the islands as part of the USGS Northern Gulf of Mexico Ecosystem Change and Hazard Susceptibility project (NGOM). The purpose of these investigations is to characterize the near-surface stratigraphy and identify the influence it has on island evolution. Since 2009, this effort provided the basis for a collaborative effort with the U.S. Army Corps of Engineers (USACE) to expand the investigation outside of GUIS boundaries as part of the Mississippi Coastal Improvement Project (MsCIP). The MsCIP program consists of structural, nonstructural, and environmental project elements to restore portions of coastal Mississippi and GUIS affected by storm impacts. In order to mitigate shoreline erosion and breaching, the project includes the placement of sand along the islands, both on the existing beaches and within the littoral zone. This action requires the location and assessment of offshore sediment deposits that can provide suitable material for shoreline renourishment. The geophysical and sample information collected by the USGS through its geologic investigations provides this information. As part of the MsCIP program, the USGS mapped over 500 square kilometers (km2) of seafloor around GUIS between March 2010 and June 2013. Interferometric swath bathymetry, sidescan sonar, and Chirp sub-bottom profiling were used to characterize seafloor elevations, texture, and the underlying stratigraphy. Seafloor and subbottom features identified in the studies include shoals, sandsheets, lowstand valley fill, tidal delta deposits, and abandoned barrier deposits. Understanding the relationships between these features and the physical processes responsible for their formation is important in characterizing the history and evolution of the barrier islands and inner shelf.
Objectives
- Understand the geologic evolution of the inner shelf
- Define the evolutionary relationships between the nearsurface geology and seafloor morphology
- Identify resources for shoreline restoration
Methodology
As part of the USGS NGOM project and the USACE MsCIP Project, extensive geological investigations were conducted along the Mississippi Barrier Islands and offshore between 2008 and 2013. The seafloor within the study area was mapped using single-beam and interferometric swath bathymetric systems and sidescan sonar. Vessel motion was recorded continuously using motion referencing units (for heave, pitch and roll), and differential Global Positioning Systems (navigation). To account for variability in sound velocity due to oceanographic conditions, water density was monitored continuously using a sound mini sound velocity sensor mounted at the swath head, and in profile through the water column through regular casts.
In the subsurface, two-dimensional profiles of the stratigraphy were acquired using seismic reflection (chirp) systems. For complete details on the data acquisition and processing, see DeWitt and others (2012); Twichell and others (2011); Pendleton and others (2010); Forde and others (2011), and Pfeiffer and others (2011).
The offshore geophysical data were collected onboard the Research Vessel (R/V) Tommy Munro, shallow-water surveys were conducted onboard the R/V Gilbert and smaller-draft research vessels. Survey lines for most of the study area were spaced 100 to 150 m apart in waters less than 10 m, and 300 m in deeper waters, parallel to the island shoreline. Tie-lines (shore perpendicular) were acquired 1 km apart. The study area covers 330 km2.
Sediment profiles were collected offshore by the USACE and inshore by the USGS using vibracore systems. The cores were 3 to 6 m in length. Each core was described macroscopically and photographed. Subsamples were collected and analyzed for grain size. The sediment cores provided correlation between the geophysical data and the stratigraphy to ground truth the remote sensing data. Details on the collection and processing of the cores can be found in Kelso and others, (2015).
Data Synthesis
- Bathymetric data were used as the foundation for the seismic, side-scan sonar, and sediment data. After the bathymetry data was processed all data were referenced to the seafloor elevation.
- Seismic data were used to create a 3-dimensional structure of the geology beneath the seafloor. Depositional units were identified and mapped in order to interpret the geologic framework.
- Stratigraphic profiles from the vibracores were used to ground truth the seismic data and to help recreate the depositional environments of each unit identified. Physical descriptions and grain-size analysis were used to characterize the physical properties of the units.
- Using seismic data, areas and volumes were calculated for the four sand units identified in the study, including calculating depth from modern seafloor to the tops of the units.
This research is part of the Geologic and Morphologic Evolution of Coastal Margins project.
This research is part of the Geologic and Morphologic Evolution of Coastal Margins project. Listed below are links to that project and related resarch tasks.
Geologic and Morphologic Evolution of Coastal Margins
Barrier Island Comprehensive Monitoring
Subsidence and Coastal Geomorphic Change in South-Central Louisiana
Integrating Mapping and Modeling to Support the Restoration of Bird Nesting Habitat at Breton Island National Wildlife Refuge
Science Support for the Mississippi Coastal Improvement Project
Geologic Evolution of Cat Island, Mississippi
Below are publications associated with this project.
Near-surface stratigraphy and morphology, Mississippi Inner Shelf, northern Gulf of Mexico
Geologic control on the evolution of the inner shelf morphology offshore of the Mississippi barrier islands, northern Gulf of Mexico, USA
Archive of sediment data from vibracores collected in 2010 offshore of the Mississippi barrier islands
Archive of single beam and swath bathymetry data collected nearshore of the Gulf Islands National Seashore, Mississippi, from West Ship Island, Mississippi, to Dauphin Island, Alabama: Methods and data report for USGS Cruises 08CCT01 and 08CCT02, July 200
Geophysical data from offshore of the Gulf Islands National Seashore, Cat Island to Western Horn Island, Mississippi
The shallow stratigraphy and sand resources offshore of the Mississippi Barrier Islands
Archive of Side Scan Sonar and Swath Bathymetry Data collected during USGS Cruise 10CCT02 Offshore of Petit Bois Island Including Petit Bois Pass, Gulf Islands National Seashore, Mississippi, March 2010
Archive of digital Chirp subbottom profile data collected during USGS cruises 10CCT01, 10CCT02, and 10CCT03, Mississippi and Alabama Gulf Islands, March and April 2010
Below are partners associated with this project.
- Overview
Since 2007, the USGS (with NPS and USACE) has been mapping the seafloor and substrate around the Mississippi barrier islands to characterize the near-surface stratigraphy and identify the influence it has on island evolution and fate.
Sources/Usage: Public Domain. Visit Media to see details.Location of geophysical and sediment core data collected between 2009 and 2013, and used in the Mississippi Coastal Improvement Project (MsCIP) project. (Public domain.) This research is part of the Geologic and Morphologic Evolution of Coastal Margins project.
Coastal Mississippi is protected by a series of barrier islands (Petit Bois, Horn, East Ship, West Ship, and Cat) that comprise the Gulf Islands National Seashore (GUIS). The islands support an ecologically diverse shoreline that provides habitat for wildlife including migratory birds and endangered animals. The majority of GUIS is submerged, and aquatic environments include dynamic tidal inlets, ebb-tide deltas, sandy shorelines, and seagrass beds. The islands are in a state of decline, with land areas severely reduced during the past century by storms, sea-level rise, and anthropogenic alteration. Since the mid-1800s up to 64 percent of GUIS surface area has been lost. Heavy damage is inflicted on the islands by frequent hurricane events, including Hurricane Katrina in 2005, which passed by as a Category 3 storm and battered the islands with winds of more than 160 kilometers per hour and a storm surge up to 9 meters.
Since 2007, the USGS, in collaboration with the National Park Service, has been mapping the seafloor and substrate around the islands as part of the USGS Northern Gulf of Mexico Ecosystem Change and Hazard Susceptibility project (NGOM). The purpose of these investigations is to characterize the near-surface stratigraphy and identify the influence it has on island evolution. Since 2009, this effort provided the basis for a collaborative effort with the U.S. Army Corps of Engineers (USACE) to expand the investigation outside of GUIS boundaries as part of the Mississippi Coastal Improvement Project (MsCIP). The MsCIP program consists of structural, nonstructural, and environmental project elements to restore portions of coastal Mississippi and GUIS affected by storm impacts. In order to mitigate shoreline erosion and breaching, the project includes the placement of sand along the islands, both on the existing beaches and within the littoral zone. This action requires the location and assessment of offshore sediment deposits that can provide suitable material for shoreline renourishment. The geophysical and sample information collected by the USGS through its geologic investigations provides this information. As part of the MsCIP program, the USGS mapped over 500 square kilometers (km2) of seafloor around GUIS between March 2010 and June 2013. Interferometric swath bathymetry, sidescan sonar, and Chirp sub-bottom profiling were used to characterize seafloor elevations, texture, and the underlying stratigraphy. Seafloor and subbottom features identified in the studies include shoals, sandsheets, lowstand valley fill, tidal delta deposits, and abandoned barrier deposits. Understanding the relationships between these features and the physical processes responsible for their formation is important in characterizing the history and evolution of the barrier islands and inner shelf.
Example 2-dimensional chirp profile offshore of the Gulf Islands National Seashore (GUIS) shows many morphologic and subsurface features. Pleistocene lowstand fluvial deposits are overlain by estuarine-marine sediments deposited during subsequent sea-level rise. These sediments are in turn overlain by Late Holocene sandsheets and shoals. (Public domain.) Seafloor and subsurface deposits identified during the Mississippi Coastal Improvement Project (MsCIP) study. The deposits are potential sediment resource candidates for use in island restoration. (Public domain.) Objectives
- Understand the geologic evolution of the inner shelf
- Define the evolutionary relationships between the nearsurface geology and seafloor morphology
- Identify resources for shoreline restoration
Methodology
Side-scan sonar mosaic offshore of Petit Bois Island showing shore-oblique sand ridges trending SE-NW across the study area. The shoals are targeted as possible sand resources for island restoration. (Public domain.) As part of the USGS NGOM project and the USACE MsCIP Project, extensive geological investigations were conducted along the Mississippi Barrier Islands and offshore between 2008 and 2013. The seafloor within the study area was mapped using single-beam and interferometric swath bathymetric systems and sidescan sonar. Vessel motion was recorded continuously using motion referencing units (for heave, pitch and roll), and differential Global Positioning Systems (navigation). To account for variability in sound velocity due to oceanographic conditions, water density was monitored continuously using a sound mini sound velocity sensor mounted at the swath head, and in profile through the water column through regular casts.
In the subsurface, two-dimensional profiles of the stratigraphy were acquired using seismic reflection (chirp) systems. For complete details on the data acquisition and processing, see DeWitt and others (2012); Twichell and others (2011); Pendleton and others (2010); Forde and others (2011), and Pfeiffer and others (2011).
The offshore geophysical data were collected onboard the Research Vessel (R/V) Tommy Munro, shallow-water surveys were conducted onboard the R/V Gilbert and smaller-draft research vessels. Survey lines for most of the study area were spaced 100 to 150 m apart in waters less than 10 m, and 300 m in deeper waters, parallel to the island shoreline. Tie-lines (shore perpendicular) were acquired 1 km apart. The study area covers 330 km2.
Sediment profiles were collected offshore by the USACE and inshore by the USGS using vibracore systems. The cores were 3 to 6 m in length. Each core was described macroscopically and photographed. Subsamples were collected and analyzed for grain size. The sediment cores provided correlation between the geophysical data and the stratigraphy to ground truth the remote sensing data. Details on the collection and processing of the cores can be found in Kelso and others, (2015).
Data Synthesis
- Bathymetric data were used as the foundation for the seismic, side-scan sonar, and sediment data. After the bathymetry data was processed all data were referenced to the seafloor elevation.
- Seismic data were used to create a 3-dimensional structure of the geology beneath the seafloor. Depositional units were identified and mapped in order to interpret the geologic framework.
- Stratigraphic profiles from the vibracores were used to ground truth the seismic data and to help recreate the depositional environments of each unit identified. Physical descriptions and grain-size analysis were used to characterize the physical properties of the units.
- Using seismic data, areas and volumes were calculated for the four sand units identified in the study, including calculating depth from modern seafloor to the tops of the units.
This research is part of the Geologic and Morphologic Evolution of Coastal Margins project.
- Science
This research is part of the Geologic and Morphologic Evolution of Coastal Margins project. Listed below are links to that project and related resarch tasks.
Geologic and Morphologic Evolution of Coastal Margins
A combination of geophysics, sediment sampling, and chronology techniques are used to characterize the regional geomorphologic response of coastal systems to environmental changes.Barrier Island Comprehensive Monitoring
Historical and newly acquired data were used to assess and monitor changes in the aerial and subaqueous extent of islands, habitat types, sediment properties, environmental processes, and vegetation composition.Subsidence and Coastal Geomorphic Change in South-Central Louisiana
New methods will investigate coastal subsidence on and around barrier islands before and after restoration.Integrating Mapping and Modeling to Support the Restoration of Bird Nesting Habitat at Breton Island National Wildlife Refuge
In response to storms, reduced sediment supply, and sea-level rise, Breton Island is rapidly deteriorating, impacting the available nesting habitat of endangered seabirds. This study provides critical information regarding the physical environment of the island system.Science Support for the Mississippi Coastal Improvement Project
Since 2007, the USGS (with NPS and USACE) has been mapping the seafloor and substrate around the Mississippi barrier islands to characterize the near-surface stratigraphy and identify the influence it has on island evolution and fate.Geologic Evolution of Cat Island, Mississippi
The geologic evolution of Cat Island has been influenced by deltaic, lagoonal/estuarine, tidal, and oceanographic processes, resulting in a complex stratigraphic record. - Publications
Below are publications associated with this project.
Near-surface stratigraphy and morphology, Mississippi Inner Shelf, northern Gulf of Mexico
Over the past decade, the Mississippi Barrier Islands have been the focus of a comprehensive geologic investigation by the U.S. Geological Survey (USGS), in collaboration with the U.S. Army Corps of Engineers (USACE) and the National Park Service (NPS). The islands (Dauphin, Petite Bois, Horn, East Ship, West Ship, and Cat) are part of the Gulf Islands National Seashore (GUIS), and provide a diverAuthorsJames G. Flocks, Jack Kindinger, Kyle W. Kelso, Julie Bernier, Nancy T. DeWitt, Michael FitzHarrisGeologic control on the evolution of the inner shelf morphology offshore of the Mississippi barrier islands, northern Gulf of Mexico, USA
Between 2008 and 2013, high-resolution geophysical surveys were conducted around the Mississippi barrier islands and offshore. The sonar surveys included swath and single-beam bathymetry, sidescan, and chirp subbottom data collection. The geophysical data were groundtruthed using vibracore sediment collection. The results provide insight into the evolution of the inner shelf and the relationship bAuthorsJames G. Flocks, Jack L. Kindinger, Kyle W. KelsoArchive of sediment data from vibracores collected in 2010 offshore of the Mississippi barrier islands
In 2010, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center collected sediment cores from coastal waters offshore of the Mississippi barrier islands. With funding support from the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility project, 65 subaqueous sediment cores were collected over an area of 480 square kilometers (km2), from ShAuthorsKyle W. Kelso, James G. FlocksArchive of single beam and swath bathymetry data collected nearshore of the Gulf Islands National Seashore, Mississippi, from West Ship Island, Mississippi, to Dauphin Island, Alabama: Methods and data report for USGS Cruises 08CCT01 and 08CCT02, July 200
During the summers of 2008 and 2009 the USGS conducted bathymetric surveys from West Ship Island, Miss., to Dauphin Island, Ala., as part of the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility project. The survey area extended from the shoreline out to approximately 2 kilometers and included the adjacent passes (fig. 1). The bathymetry was primarily used to create a topAuthorsNancy T. DeWitt, James G. Flocks, Elizabeth A. Pendleton, Mark E. Hansen, B.J. Reynolds, Kyle W. Kelso, Dana S. Wiese, Charles R. WorleyGeophysical data from offshore of the Gulf Islands National Seashore, Cat Island to Western Horn Island, Mississippi
This report contains the geophysical and geospatial data that were collected along the western offshore side of the Gulf Islands of Mississippi on the research vessel Tommy Munro during two cruises in 2010. Geophysical data were collected by the U.S. Geological Survey in Woods Hole, Massachusetts, and St. Petersburg, Forida, in cooperation with the U.S. Army Corps of Engineers Mobile District. BatAuthorsE.A. Pendleton, W. E. Baldwin, W. W. Danforth, N. T. DeWitt, A.S. Forde, D. S. Foster, K.W. Kelso, W.R. Pfeiffer, A.M. Turecek, J. G. Flocks, D. C. TwichellThe shallow stratigraphy and sand resources offshore of the Mississippi Barrier Islands
Coastal Mississippi is protected by a series of barrier islands ranging in length from 10-25 kilometers that are less than 2 kilometers wide. The majority of these islands comprise the Gulf Islands National Seashore (GUIS), an ecologically diverse shoreline that provides habitat for wildlife including migratory birds and endangered animals. The majority of GUIS is submerged, and aquatic environmenAuthorsDavid Twichell, Elizabeth A. Pendleton, Wayne Baldwin, David Foster, James Flocks, Kyle Kelso, Nancy DeWitt, William Pfeiffer, Arnell Forde, Jason Krick, John BaehrArchive of Side Scan Sonar and Swath Bathymetry Data collected during USGS Cruise 10CCT02 Offshore of Petit Bois Island Including Petit Bois Pass, Gulf Islands National Seashore, Mississippi, March 2010
In March of 2010, the U.S. Geological Survey (USGS) conducted geophysical surveys offshore of Petit Bois Island, Mississippi, and Dauphin Island, Alabama (fig. 1). These efforts were part of the USGS Gulf of Mexico Science Coordination partnership with the U.S. Army Corps of Engineers (USACE) to assist the Mississippi Coastal Improvements Program (MsCIP) and the Northern Gulf of Mexico (NGOM) EcosAuthorsWilliam R. Pfeiffer, James G. Flocks, Nancy T. DeWitt, Arnell S. Forde, Kyle Kelso, Phillip R. Thompson, Dana S. WieseArchive of digital Chirp subbottom profile data collected during USGS cruises 10CCT01, 10CCT02, and 10CCT03, Mississippi and Alabama Gulf Islands, March and April 2010
This Digital Versatile Disc (DVD) publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological SurvAuthorsArnell S. Forde, Shawn V. Dadisman, James G. Flocks, Dana S. Wiese, Nancy T. DeWitt, William R. Pfeiffer, Kyle W. Kelso, Phillip R. Thompson - Partners
Below are partners associated with this project.