Christopher G. Smith Alisha M. Ellis 20241220 1.0 tabular digital data Christopher G. Smith Alisha M. Ellis 20241220 1.0 tabular digital data U.S. Geological Survey data release doi:10.5066/P13BDDHQ St. Petersburg, FL U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center https://doi.org/10.5066/P13BDDHQ Location and elevation data were collected along with peat auger cores during six U.S. Geological Survey (USGS) field activities from 2013-2018 in and around Grand Bay, Mississippi (MS) and Alabama (AL) and used in models described by Smith and others (2024). Peat auger cores were described, photographed, and the thickness of the peat unit was measured with a measuring tape. Following collection, the distance from the core location to various geomorphic boundaries (e.g., upland, marsh shoreline, water edge, etc.) and other metrics (angle and width of marsh) were determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro (version 3.1) using 2015 shorelines from Terrano and others (2018). This dataset includes all the aforementioned metrics along with the angle from the shoreline and upland boundary to the core locations. The cores used in this data release were collected during the following six field activities identified by the following USGS assigned field activity numbers (FANs): 13BIM01, 2014-323-FA (alternate FAN 14CCT01), 2016-331-FA (16CCT03), 2016-358-FA (16CCT07), 2017-315-FA (17CCT02), and 2018-332-FA (18CCT01). Additional marsh and estuarine data from these six field activities (sediment characteristics, loss-on-ignition (LOI), foraminiferal census data, radiochemistry, and site location information) are available in previously published data releases, which are cross-referenced in the metadata of this data release. Downloadable data are available as a comma-separated values text file (.csv) and Federal Geographic Data Committee (FGDC) metadata (.txt and .xml). Dissemination of field collected location data, peat thickness measurements, and ArcGIS Pro measurements used for calculations of angle and distance to the shoreline and upland boundary. Data is associated with six field activity numbers (FANs): 13BIM01, 2014-323-FA (alternate FAN 14CCT01), 2016-331-FA (16CCT03), 2016-358-FA (16CCT07), 2017-315-FA (17CCT02), and 2018-332-FA (18CCT01) in and around Grand Bay and Point aux Chenes marshes, Mississippi and Alabama. To ensure that USGS- St. Petersburg Coastal and Marine Science Center (SPCMSC) data management protocols were followed, all surveys were assigned USGS field activity numbers (FANs). Additional survey details for each FAN are available on the Coastal and Marine Geoscience Data System (CMGDS) and in the following USGS data releases: Marot and others (2018; 2019), Ellis and others (2022), and Smith and others (2020). To view field activity details for any of the datasets included in this data release, the CMGDS can be used to look up USGS FANs, by replacing the FAN in the following URL: https://cmgds.marine.usgs.gov/fan_info.php?fan=2014-323-FA. 20130414 20180718 ground condition Complete As needed -88.43337962 -88.31070549 30.41425474 30.34965288 USGS Metadata Identifier USGS:e5834b32-ccad-464f-b836-0a09bd2a1966 ISO 19115 Topic Category environment location geoscientificInformation elevation USGS Thesaurus rocks and deposits geology unconsolidated deposits stratigraphic thickness datasets field inventory and monitoring field sampling augering core analysis cartography None sediment peat thickness marsh core U.S. Geological Survey USGS U.S. Geological Survey St. Petersburg Coastal and Marine Science Center SPCMSC 13BIM01 14CCT01 16CCT03 16CCT07 17CCT02 18CCT01 None Grand Bay National Estuarine Research Reserve NERR Geographic Names Information System (GNIS) Gulf of Mexico Mississippi Alabama Grand Bay Point Aux Chenes Bayou Cumbest Middle Bay Bayou Heron None Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests that it be acknowledged as the originator of this dataset in any future products or research derived from these data. This metadata record should be reviewed in its entirety. U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center Christopher G. Smith Research Geologist Mailing and physical

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St. Petersburg FL 33701 US (727) 502-8000 cgsmith@usgs.gov Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies in data collection methods. These data are not legal documents and are not to be used as such. Environment as of Metadata Creation: Environment as of Metadata Creation: Virtual Windows Machine run on Apple iMac workstation; Microsoft Excel for Microsoft 365 MSO version 2302; VDatum version 3.6 (https://vdatum.noaa.gov/); NovAtel's GrafNav version 2.3 and newer; Esri ArcGIS Pro version 3.1. Marot, M.E., Kelso, K.W., Osterman, L.E., DeWitt, N.T., and Smith, C.G. 20180713 St. Petersburg, Florida U.S. Geological Survey Contains 13BIM01 site information, sediment physical properties, grain-size, gamma spectroscopy, foraminifera, stable isotope, element concentration and core data. https://doi.org/10.5066/F7H70DSZ Marot, M.E., Smith, C.G., McCloskey, T.A., Locker, S.D., Khan, N.S., and Smith, K.E.L. 20190301 St. Petersburg, Florida U.S. Geological Survey Contains 14CCT01, 16CCT03, 16CCT07 and other FAN data not directly associated with this data release. Data types include site information, sediment physical properties, grain-size, gamma and alpha spectroscopy, foraminifera, stable isotope, IPC-AES, radiocarbon, XRF, CTD, and core data. https://doi.org/10.5066/P9FO8R3Y Kathryn E.L. Smith, Joseph F. Terrano, Jonathan Pitchford, Michael Brochard, Joseph M. Vargas, Isabelle D. Atchia, Cheyenne S. Everhart, and Christopher G. Smith 20200713 St. Petersburg, Florida U.S. Geological Survey Contains data from a related NST study in Point aux Chenes areas of the GNDNERR. https://doi.org/10.5066/P9ONI8PS Ellis, A.M., Smith, C.G., Vargas, J.M., and Everhart, C.S. 20220418 St. Petersburg, Florida U.S. Geological Survey Contains data from a related surface sample study in the Middle Bay area of the GNDNERR. https://doi.org/10.5066/P9BLFW2G Smith, C.G., Bernier, J., Ellis, A.M., and Smith, K.E.L. 20241219 Online Elsevier https://doi.org/10.1016/j.acags.2024.100215 Location accuracy for each site/FAN is listed in its original data release, refer to those publication for more information. Peat thickness was measured in the field to the nearest 1-centimeter (cm). This dataset includes site locations, Universal Transverse Mercator (UTM) x and y planar coordinates in meters, orthometric elevations/heights, observed peat thickness, the distance from the core site to both the upland boundary and shoreline, and the angle along the marsh transects, width along the marsh transect, as well as distances (only) for water's edge, Bayou Heron, Middle Bayou, and Bayou Cumbest for the following USGS assigned alternate FANs: 13BIM01, 14CCT01, 16CCT03, 16CCT07, 17CCT02, and 18CCT01. This data release contains peat thickness data collected in Grand Bay, Mississippi and Alabama that has not been previously published in a USGS data release (referenced above). Terrano, J.F., Smith, K.E.L., Pitchford, J., McIlwain, J., and Archer, M. 20180926 2.0 vector digital data St. Petersburg, FL - St. Petersburg Coastal and Marine Science Center https://doi.org/10.5066/P9JMA8WK shapefile 2015 ground condition Terrano and others (2018) Shorelines from 2015 used to determine the distance from the core location to the shoreline and upland boundary in ArcGIS Pro. During the field missions at each site, 50-cm vertical sections of sediment were extracted from the marsh subsurface using a Russian Peat Auger; each section was successively deeper than the previous until the auger met refusal at depth. Each vertical core consisted of half-cylinder sections of marsh subsurface sediment. Each core segment was scaled with a measuring tape, described in the field for basic/visual stratigraphic and sedimentologic characteristics, and photographed in the field. If the peat unit was fully penetrated, the overall thickness of the overlying organic-rich unit was documented and recorded on site. Upon return from the field, photographs of the cores were examined to verify the peat thickness field observation. If the field description and photographed organic-rich unit for each were in agreement, the marsh thickness was included. A total of 57 cores were collected within the Grand Bay study area and are included in this release. 2018 U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center Christopher G. Smith Research Geologist Mailing and physical

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St. Petersburg FL 33701 U.S. (727) 502-8000 cgsmith@usgs.gov Positional data (location and elevation) and the associated methods used to derive the horizontal and vertical positions have been published and described in Marot and others (2018), Marot and others (2019), Ellis and others (2022), and Smith and others (2020). All USGS collected location data utilized a global positioning system (GPS) base station erected on National Geodetic Survey (NGS) permanent identifier (PID) DO5987 (B166) located at the boat ramp at the end of Bayou Heron Road in Grand Bay, MS. A differential GPS (DGPS) rover receiver, with a known measured antenna height, was used in the field to collect positional data with occupation times of 30 minutes. Base station coordinates were established using the NGS On-Line Position User Service (OPUS, https://geodesy.noaa.gov/OPUS/). Location data was processed with NovAtel's GrafNav. Location data collected by the Grand Bay National Estuarine Research Reserve utilized a Trimble R10 GNSS and TSC3 data collector. Vertical and horizontal errors associated with each dataset can be found in the metadata of its associated data release. 2018 U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center Christopher G. Smith Research Geologist Mailing and physical

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St. Petersburg FL 33701 U.S. (727) 502-8000 cgsmith@usgs.gov All field-collected location data was brought into ArcGIS Pro (v. 3.1) in its native format (varied by FAN and available in the associated metadata files) and converted/projected to a Universal Transverse Mercator (UTM) planar coordinate system (zone 16) to allow for all measurements to be cartesian lengths. Geospatial variables were extracted from the marsh core locations relative to the arcuate-shaped feature of the estuarine-marsh and upland-marsh boundaries in the study area which reflect the antecedent morphology. Using ArcGIS Pro 3.1 (hereafter AGP) with a UTM projected coordinate system, the upland and river boundary from the 2015 shoreline data set used by Terrano and others (2018) were digitized. Additional smoothed, offset boundaries (buffered) were created from the detailed boundaries to reflect the more general arcuate nature of the Middle and Grand Bays using the Buffer tool in AGP and a 50-meter offset. The shoreline boundary line was converted to points with ten-meter spacing using Terrano and others (2018) transects using the AGP 'Intersect' geoprocessing tool. The 'Near Table' geoprocessing tool was used with Geodesic setting and with the core dataset as the input layer and the shoreline point shapefile as the near layer. Core coordinates (original as measured with GPS), Core Site ID (as a static input), near angle, distance, and targeted shoreline point coordinates were produced as part of the tool s results. A temporary point file shapefile (hereafter the target-shoreline point) was created from the Near Table results (approximately 500 points). The near angle computed as core-to-shoreline was transformed to bearing to reflect shoreline-to-core and added to the target-shoreline point file. The Bearing Distance to Line geoprocessing tool was used to construct a new line shapefile with the target-shoreline point as the origin, transformed bearing, and a set distance of 5000 meters. The point intersection (coordinates) between the generated lines and the upland boundary was added to the target-shoreline point file. The lines were then extended to intersect the buffered boundaries using the Extend Line tool in AGP and the distance of the line updated (i.e., distance between the modified boundaries). This distance was added to target-shoreline-point file. The target-shoreline-point file was reduced to one record per core site using the minimum distance between the modified boundaries per core site. Distance to shoreline, distance to upland, and width were computed from the coordinates of each core and the respective near shoreline point and near upland point. Distance of each new line segment (distance from to the upland boundary, distance to the shoreline, and width) along with bearing of near transect was written to the original core point shapefile s attribute table. The closest distance between a core site and nearby major tidal creeks (Bayou Heron, Middle Bayou, and Bayou Cumbest) and the water s edge (closest shoreline location) were measured. The Near tool in AGP was executed with the core point shapefile as input and line shapefile of the thalweg of each major tidal creek. The shortest distance between each core point and three tidal creeks was added to core point shapefile as distance to Bayou Heron, distance to Middle Bayou, and distance to Bayou Cumbest. Similarly, the Near tool was run between the core site and the shoreline shapefile and added to the core point shapefile as distance to water s edge. The resultant point shapefile was exported as a comma-separated values (.csv) file. The CSV file was modified in Microsoft Excel to include the following attributes: altFAN, SiteID, UTMxNAD83, UTMyNAD83, dGPS elevation, peat thickness, base peat, marsh width, bearing of marsh transect, distance to shoreline, distance to upland, distance to water's edge, distance to Bayou Heron, distance to Middle Bayou, and distance to Bayou Cumbest. All distance metrics are in meters. Terrano and others (2018) 2020 PeatThickness_SiteInfo.csv U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center Christopher G. Smith Research Geologist Mailing and physical

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St. Petersburg FL 33701 U.S. (727) 502-8000 cgsmith@usgs.gov Point Point 57 Universal Transverse Mercator 16 0.9996 -87.0 0.0 500000.0 0.0 coordinate pair 0.6096 0.6096 Meter North American Datum 1983 Geodetic Reference System 80 6378137.000000 298.257222101 North American Vertical Datum 1988 0.0001 meters Attribute values PeatThickness_SiteInfo.csv Comma-separated values text file (.csv) including the site locations, Universal Transverse Mercator (UTM) x and y planar coordinates in meters, orthometric elevations/heights, observed peat thickness, the distance from the core site to both the upland boundary and shoreline, and the angle along the marsh transects, width along the marsh transect, as well as distances (only) for water's edge, Bayou Heron, Middle Bayou, and Bayou Cumbest. USGS USGS_Alt_FAN Alternate field activity number assigned by the USGS to the sample collection/survey. USGS Alternate FAN numbers were assigned by the USGS as YYLLLXX, where YY is the 2-digit year, LLL equals either CCT (coastal change and transport) or BIM (barrier island migration), and XX is the trip number. SiteID Site identifier assigned by USGS scientists consisting of GB to indicate Grand Bay and a three-digit number, representing the study site. USGS Alphanumeric site identifier assigned as the following: the site location name abbreviation ('GB' for Grand Bay) followed by a three-digit number. UTMx_NAD83_m Universal Transverse Mercator (UTM, zone 16) horizontal station location, on the x coordinate plane, in meters (North American Datum of 1983). USGS 362322.7915 374027.223 meters UTMy_NAD83_m Universal Transverse Mercator (UTM, zone 16) vertical station location, on the y coordinate plane, in meters (North American Datum of 1983). USGS 3358400.473 3365419.583 meters Orth_Height_m The orthometric height, or land elevation, in meters, of each site relative to the North American Vertical Datum of 1988 (NAVD88) and GEOID12A. USGS -0.026 0.750 meters Obs_PeatThickness_m The observed or measured thickness of the peat layer in the peat auger cores collected in the field, recorded in meters. USGS 0.04 1.69 meters BasePeat_m The estimated elevation of the basal marsh contact, in meters, at each site relative to NAVD88 GEOID12A. USGS -1.114 0.681 meters (m) Bearing_of_MarshTransect_degrees The bearing of the line created from the shoreline, through the core location, extending to the upland boundary, determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro. USGS 38.109197 310.419187 degrees Distance_Upland_m The distance from the core location to the upland boundary as determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with 2015 shorelines, in meters. USGS 2.249366435 3452.165406 meters (m) Distance_Shore_m The distance from the core location to the shoreline as determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with 2015 shorelines, in meters. USGS 0.777162307 2835.353174 meters (m) Marsh_width_m The distance along the line for each site from the upland boundary to the core location, out to the shoreline, as determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with 2015 shorelines, in meters. Also defined as: Dist_Shoreline_2015_m + Dist_Upland_2015_m. USGS 156.3708545 4027.886561 meters (m) Distance_watersedge_m The distance from the core location to the closest shoreline feature. Values determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with 2015 shorelines, in meters. USGS 1.186665625 411.1475323 meters (m) Distance_bayouheron_m The distance from the core location to the closest shoreline feature. Values determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with modified 2015 shoreline of Bayou Heron, in meters. USGS 104.8223491 8081.254984 meters (m) Distance_middlebayou_m The distance from the core location to the closest shoreline feature . Values determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with modified 2015 shoreline of Middle Bayou, in meters. USGS 58.33454547 9362.769929 meters (m) Distance_bayoucumbest_m The distance from the core location to the closest shoreline feature. Values determined using geoprocessing tools from the Data Management and Analysis Toolboxes in ArcGIS Pro with modified 2015 shoreline of Bayou Cumbest, in meters. USGS 103.9393615 9457.296124 meters (m) This data product includes field collected and ArcGIS Pro derived data associated with six USGS FANs. Data includes site locations, Universal Transverse Mercator (UTM) x and y planar coordinates in meters, orthometric elevations/heights, observed peat thickness, the distance from the core site to both the upland boundary and shoreline, and the angle along the marsh transects, width along the marsh transect, as well as distances (only) for water's edge, Bayou Heron, Middle Bayou, and Bayou Cumbest. The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center USGS SPCMSC Data Management mailing and physical

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Saint Petersburg FL 33701 United States 727-502-8000 gs-g-spcmsc_data_inquiries@usgs.gov PeatThickness_SiteInfo.csv Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. comma-delimited text 1.0 WinZip,7-zip Unzip https://coastal.er.usgs.gov/data-release/doi-P13BDDHQ/data/PeatThickness_SiteInfo.zip None None 20241220 U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center USGS SPCMSC Data Management Mailing and physical

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St. Petersburg FL 33701 U.S. (727) 502-8000 gs-g-spcmsc_data_inquiries@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998