The northeastern North Carolina coastal system, from False Cape, Virginia, to Cape Lookout, North Carolina, has been studied by a cooperative research program that mapped the Quaternary geologic framework of the estuaries, barrier islands, and inner continental shelf. This information provides a basis to understand the linkage between geologic framework, physical processes, and coastal evolution at time scales from storm events to millennia. The study area attracts significant tourism to its parks and beaches, contains a number of coastal communities, and supports a local fishing industry, all of which are impacted by coastal change. Knowledge derived from this research program can be used to mitigate hazards and facilitate effective management of this dynamic coastal system.
This regional mapping project produced spatial datasets of high-resolution geophysical (bathymetry, backscatter intensity, and seismic reflection) and sedimentary (core and grab-sample) data. The high-resolution geophysical data were collected during numerous surveys within the back-barrier estuarine system, along the barrier island complex, in the nearshore, and along the inner continental shelf. Sediment cores were taken on the mainland and along the barrier islands, and both cores and grab samples were taken on the inner shelf. Data collection was a collaborative effort between the U.S. Geological Survey (USGS) and several other institutions including East Carolina University (ECU), the North Carolina Geological Survey, and the Virginia Institute of Marine Science (VIMS).
The high-resolution geophysical data of the inner continental shelf were collected during six separate surveys conducted between 1999 and 2004 (four USGS surveys north of Cape Hatteras: 1999-045-FA, 2001-005-FA, 2002-012-FA, 2002-013-FA, and two USGS surveys south of Cape Hatteras: 2003-003-FA and 2004-003-FA) and cover more than 2600 square kilometers of the inner shelf. Single-beam bathymetry data were collected north of Cape Hatteras in 1999 using a Furuno fathometer. Swath bathymetry data were collected on all other inner shelf surveys using a SEA, Ltd. SwathPLUS 234-kHz bathymetric sonar. Chirp seismic data as well as sidescan-sonar data were collected with a Teledyne Benthos (Datasonics) SIS-1000 north of Cape Hatteras along with boomer seismic reflection data (cruises 1999-045-FA, 2001-005-FA, 2002-012-FA and 2002-013-FA). An Edgetech 512i was used to collect chirp seismic data south of Cape Hatteras (cruises 2003-003-FA and 2004-003-FA) along with a Klein 3000 sidescan-sonar system. Sediment samples were collected with a Van Veen grab sampler during four of the USGS surveys (1999-045-FA, 2001-005-FA, 2002-013-FA, and 2004-003-FA). Additional sediment core data along the inner shelf are provided from previously published studies.
A cooperative study, between the North Carolina Geological Survey and the Minerals Management Service (MMS cores), collected vibracores along the inner continental shelf offshore of Nags Head, Kill Devils Hills and Kitty Hawk, North Carolina in 1996. The U.S. Army Corps of Engineers collected vibracores along the inner shelf offshore of Dare County in August 1995 (NDC cores) and July-August 1995 (SNL cores). These cores are curated by the North Carolina Geological Survey and were used as part of the ground validation process in this study.
Nearshore geophysical and core data were collected by the Virginia Institute of Marine Science. The nearshore is defined here as the region between the 10-m isobath and the shoreline. High-resolution bathymetry, backscatter intensity, and chirp seismic data were collected between June 2002 and May 2004. Vibracore samples were collected in May and July 2005.
Shallow subsurface geophysical data were acquired along the Outer Banks barrier islands using a ground-penetrating radar (GPR) system. Data were collected by East Carolina University from 2002 to 2005. Rotasonic cores (OBX cores) from five drilling operations were collected from 2002 to 2006 by the North Carolina Geological Survey as part of the cooperative study with the USGS. These cores are distributed throughout the Outer Banks as well as the mainland.
The USGS collected seismic data for the Quaternary section within the Albemarle-Pamlico estuarine system between 2001 and 2004 during six surveys (2001-013-FA, 2002-015-FA, 2003-005-FA , 2003-042-FA, 2004-005-FA, and 2004-006-FA). These surveys used Geopulse Boomer and Knudsen Engineering Limited (KEL) 320BR Chirp systems, except cruise 2003-042-FA, which used an Edgetech 424 Chirp and a boomer system. The study area includes Albemarle Sound and selected tributary estuaries such as the South, Pungo, Alligator, and Pasquotank Rivers; Pamlico Sound and trunk estuaries including the Neuse and Pamlico Rivers; and back-barrier sounds including Currituck, Croatan, Roanoke, Core, and Bogue.
A regional survey of the North Carolina Outer Banks simultaneously collected nearshore bathymetry and acoustic backscatter data using an interferometric swath system (Submetrix series 2000) at a frequency of 234 kHz. This system allows interpretation of the spatial relationship of bathymetry to sediment distribution by enabling distinction between acoustic returns of high incident angles from seafloor sediments with high backscatter characteristics, and by eliminating the need to account for towfish layback artifacts. The system was mounted on the bow of an amphibious vehicle (U.S. Army Corps of Engineers Field Research Facility-operated LARC5) and was used in conjunction with a motion sensor (TSSDM05), compass, and real-time kinematic global positioning system to obtain horizontal and vertical precision of about 10 cm.
Acoustic backscatter is displayed as grayscale image where values correspond to the varied strength of the returned beam signal. The intensity of the sound signal received by the sonar tow vehicle is digitally represented as high (light-toned) or low (dark-toned) backscatter. Backscatter signals are influenced by the amount of acoustic signal reflected off of the seafloor. High backscatter indicates a strong signal reflection and symbolizes areas of coarse material. Low backscatter implies a weak signal reflection and marks areas of fine surficial sediment.
Acquisition System: Submetrix 2000 Series Interferometric System
Frequency: 234 kHz
Motion Sensor Information: TSS DM05 (motion); KVH Compass (heading only)
Navigation: Real-Time Kinematic Global Positioning System (RTK-GPS)
Raw Data Format: proprietary binary format *.sxr
Survey Layout: The entire survey area (~40 km alongshore distance) was separated into eight 5 km blocks, Block 1 being the most northern area and Block 8, the farthest south. Approximately 12 lines were planned in each block: 10 shore-parallel and 2 shore-perpendicular. The line closest to shore was line 1 while line 10 was the furthest from shore (~W to E). The spacing between the 5 innermost and outermost lines was 100 m and 150 m respectively. The spacing between the shore-perpendicular lines was ~2.5 km. Not all lines were surveyed depending on time/weather/equipment constraints. The naming convention of the shore-parallel lines is the block# followed by an underscore which is then followed by the line number (blockx_linex). The naming of the shore-perpendicular lines varied, but generally started with the block #, underscore and the whether the line was in the north or south of the survey block (blockx_ntie, etc).
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: sidescan sonar
Theme_Keyword: acoustic backscatter
Theme_Keyword: seafloor mapping
Theme_Keyword: marine geology
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: Coastal and Marine Geology Program
Theme_Keyword: Woods Hole Coastal and Marine Science Center
Theme_Keyword: Virginia Institute of Marine Science
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: sea-floor acoustic reflectivity
Theme_Keyword: image mosaics
Theme_Keyword: interferometric sonar
Theme_Keyword: marine geophysics
Theme_Keyword: geospatial datasets
Place_Keyword: Kill Devil Hills
Place_Keyword: Oregon Inlet
Place_Keyword: North Carolina
Place_Keyword: Outer Banks
Place_Keyword: East Coast
Place_Keyword: United States
Place_Keyword: North America
Place_Keyword: Surf Zone
Place_Keyword: Atlantic Ocean
Public domain data are freely redistributable with proper metadata and source attribution. The USGS asks that Dr. Jesse McNinch from the Virginia Institute of Marine Sciences be referenced as the originator of this dataset in any future products or publications.
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