Page C. Valentine 20260402 1.0 Vector Digital Dataset (Polyline) data release DOI:10.5066/P13PVHRI Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey, Coastal and Marine Hazards and Resources Program https://doi.org/10.5066/P13PVHRI https://www.sciencebase.gov/catalog/item/65d7c877d34ec3e1801d813e Page C. Valentine VeeAnn A. Cross 2026 1.0 data release DOI:10.5066/P13PVHRI Reston, VA U.S. Geological Survey Suggested citation: Valentine, P.C., and Cross, V.A., 2026, Geospatial datasets of seabed topography, sediment mobility, and the distribution of geologic substrates in quadrangle 3 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: U.S. Geological Survey data release, https://doi.org/10.5066/P13PVHRI. https://doi.org/10.5066/P13PVHRI The U.S. Geological Survey (USGS), in cooperation with the National Marine Sanctuary Program of the National Oceanic and Atmospheric Administration (NOAA), has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The interpretive datasets and source information presented here are for quadrangle 3, which is one of 18 similarly-sized quadrangles that comprise the 3,700 square kilometer (km2) SBNMS region. The seabed of SBNMS is a glaciated terrain that is topographically and texturally diverse. Mapping of quadrangle 3 shows the distribution of substrates on the southeastern part of Stellwagen Bank, on adjacent banks and basins in deeper water to the east, in the eastern part of Race Point Channel to the south of the bank, and on the northern slope of Outer Cape Cod. Water depths range from ~25 m on the bank crest to ~135 m east of South Ninety Bank which lies off the eastern margin of Stellwagen Bank. The data presented here for quadrangle 3 are the foundation for Scientific Investigations Map 3544 (Valentine and Cross, 2026), which presents maps of seabed topography, ruggedness, backscatter intensity, distribution of geologic substrates, sediment mobility, distribution of fine- and coarse-grained sand, and substrate mud content. For the quadrangle 3 interpretation, data from 309 ground validation stations were analyzed, including 279 sediment samples. The geologic substrate maps of quadrangle 3 show the distribution of 21 substrates that represent a wide range of textures, such as rippled sand, immobile sand, immobile muddy sand, sand that partially veneers gravel, and boulder ridges. Not all of these substrates can be mapped as individual polygons as some scattered deposits are not coherent units mappable at the given scale. Substrate types are defined or inferred by sediment grain-size composition, surface morphology, sediment layering, the mobility or immobility of substrate surfaces, and water depth range. Scientific Investigations Map 3544 portrays the major geological elements (substrates, topographic features, processes) of environments within quadrangle 3. It is intended to be a basis for the study of sediment transport processes that affect a shallow, offshore bank and adjacent basins, for the study of the ecological requirements of invertebrate and vertebrate species that use these substrates, and to support seabed management in the region. The purpose of this dataset is to release a portion of the 1-meter (m) contours that are used in quadrangle 3 Stellwagen Bank geologic interpretation maps that aid in interpretation. The 1-m contours indicate the more hummocky relief of the seabed in areas dominated by gravel deposits and small boulder ridges. These contours accentuate low-relief topographic complexity in these areas. The contours represent a close approximation of seabed microtopography, as the resolution of the multibeam echo sounder data used to generate these data is on the order of 1 m. By contrast, 1-m contours are not shown in areas where the seabed is relatively smooth and not dominated by gravel features. Any topographic complexity in these areas is beyond the resolution of the multibeam echosounder (< 1 meter in relief) and cannot be accurately depicted by the 1-m bathymetric contours. Over 50 scientific cruises have been conducted in an effort to map Stellwagen Bank. The bathymetry of Quadrangle 3 on Stellwagen Bank is from the following 5 USGS WHCMSC field activities (ship cruises): 1994-008-FA, 1995-013-FA, 1995-033-FA, 1996-032-FA, 1996-043-FA. More information on each of these activities can be found by replacing the XXXX in the following URL with the cruise ID: https://cmgds.marine.usgs.gov/fan_info.php?fan=XXXX. For example: https://cmgds.marine.usgs.gov/fan_info.php?fan=1994-008-FA. These data have a companion report that provides the additional details and information related to the interpretation and methods. Additionally, the report contains PDF maps of the seabed interpretation. That companion report is Valentine, P.C., and Cross, V.A., 2026, Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 3 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: U.S. Geological Survey Scientific Investigations Map 3544, 8 sheets, scale 1:25,000, 30-p. pamphlet, https://doi.org/10.3133/sim3544. 1994 1996 ground condition of the original bathymetric data acquisition that these contours were derived from Complete None planned -70.222221 -70.033549 42.202860 42.091684 None Woods Hole Coastal and Marine Science Center WHCMSC USGS U.S. Geological Survey National Oceanic and Atmospheric Administration NOAA sea-floor topography Esri polyline shapefile contours Coastal and Marine Hazards and Resources Program CMHRP quadrangle 3 ISO 19115 Topic Category oceans elevation USGS thesaurus geomorphology topography bathymetry sea-floor characteristics marine geology USGS Metadata Identifier USGS:65d7c877d34ec3e1801d813e None United States U.S. east coast Stellwagen Bank National Marine Sanctuary Stellwagen Bank Stellwagen Basin North America Massachusetts Bay Massachusetts Boston, Massachusetts Atlantic Ocean No access constraints. Please see 'Distribution Information' for details. Not to be used for navigation. These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey Page C Valentine Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543 508-548-8700 x2239 508-457-2310 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with the USGS. https://www.sciencebase.gov/catalog/file/get/65d7c877d34ec3e1801d813e?name=q3_1m_contours_browse.png&allowOpen=true Thumbnail image of the portion of 1-meter contours used in the interpretation of quadrangle 3 in Stellwagen Bank National Marine Sanctuary. PNG Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of this information. Environment as of Metadata Creation: Microsoft Windows 10; ArcMap 10.8.1; QGIS 3.167 Page C. Valentine Jessica L. Baker Tanya S. Unger Christopher F. Polloni 1998 vector digital data, raster digital data Open-File Report 98-138 Reston, VA U.S. Geological Survey This publication contains additional data and information in Stellwagen Bank National Marine Sanctuary. In particular this publication was the source of the 5-meter contours that were used to aid the interpretation presented in the q3_geologic_interp shapefile available from the larger work citation. https://doi.org/10.3133/ofr98138 Page C. Valentine Tanya S. Unger Jessica L. Baker Christopher F. Polloni 1999 vector digital data, raster digital data Open-File Report 99-363 Reston, VA U.S. Geological Survey This publication contains additional data and information in Stellwagen Bank National Marine Sanctuary. This publication contains data from all 18 quadrangles, but in an older format (Arc Export Format). https://doi.org/10.3133/ofr99363 Page C. Valentine, editor 2005 raster digital data Scientific Investigations Map 2840 Reston, VA U.S. Geological Survey This publication contains additional data and information in Stellwagen Bank National Marine Sanctuary. In particular this publication contains the sun-illuminated topography raster data, seabed ruggedness raster data, and the combined backscatter intensity/sun-illuminated topography raster data that were used to aid the interpretation presented in the q3_geologic_interp shapefile available from the larger work citation. https://doi.org/10.3133/sim2840 Bradford Butman Page C. Valentine Tammie J. Middleton William W. Danforth 2007 vector digital data, raster data Data Series 99 Reston, VA U.S. Geological Survey This publication contains additional data and information in Stellwagen Bank National Marine Sanctuary. In particular quadrangles 1, 2, and 3 as well as Massachusetts Bay. https://doi.org/10.3133/ds99 Page C. Valentine Leslie B. Gallea Dann S. Blackwood Erin R. Twomey 2010 raster digital data, vector digital data Data Series 469 Reston, VA U.S. Geological Survey This publication contains additional data and information in Stellwagen Bank National Marine Sanctuary. In particular this publication contains seabed photographs and sediment texture analyses that were used to aid the interpretation presented in the q3_geologic_interp shapefile available from the larger work citation. https://doi.org/10.3133/ds469 Page C. Valentine Leslie B. Gallea 2015 raster digital data, vector digital data Scientific Investigations Map 3341 Reston, VA U.S. Geological Survey This publication contains the equivalent information as this data release, but for quadrangle 6. This publication also provides the additional details and information related to the interpretation and methods as well as PDF maps of the seabed interpretation. https://doi.org/10.3133/sim3341 Page C. Valentine VeeAnn A. Cross 2024 data release DOI:10.5066/P9W9BN3S Reston, VA U.S. Geological Survey This data release contains the equivalent information as this data release, but for quadrangle 5. https://doi.org/10.5066/P9W9BN3S Page C. Valentine VeeAnn A. Cross 2024 Scientific Investigations Map 3515 Reston, VA U.S. Geological Survey This report is the companion publication of the data release for quadrangle 5 that provides the additional details and information related to the interpretation and methods. Additionally, the report contains PDF maps of the seabed interpretation. The report also provides additional references related to the work in Stellwagen Bank National Marine Sanctuary. https://doi.org/10.3133/sim3515 Page C. Valentine VeeAnn A. Cross 2024 data release DOI:10.5066/P9UL3LWN Reston, VA U.S. Geological Survey This data release contains the equivalent information as this data release, but for quadrangle 2. https://doi.org/10.5066/P9UL3LWN Page C. Valentine VeeAnn A. Cross 2024 Scientific Investigations Map 3530 Reston, VA U.S. Geological Survey This report is the companion publication of the data release that provides the additional details and information related to the interpretation and methods for quadrangle 2. Additionally, the report contains PDF maps of the seabed interpretation. The report also provides additional references related to the work in Stellwagen Bank National Marine Sanctuary. https://doi.org/10.3133/sim3530 Page C. Valentine VeeAnn A. Cross 2026 Scientific Investigations Map 3544 Reston, VA U.S. Geological Survey This report is the companion publication of the data release for quadrangle 3 that provides the additional details and information related to the interpretation and methods. Additionally, the report contains PDF maps of the seabed interpretation. The report also provides additional references related to the work in Stellwagen Bank National Marine Sanctuary. https://doi.org/10.3133/sim3544 These 1-m contours are based on unsmoothed bathymetry terrain, and the contours themselves have not been smoothed or generalized. For this reason, these 1-m contours could possibly intersect or cross 5-m contours (Valentine and others, 1998) of the same area that are based on a filtered topography. These contours were originally created in Arc/Info software, so may vary from contours created in other software packages using the same underlying bathymetry grid. This dataset only represents a portion of the 1-m contours present in quadrangle 3 of the Stellwagen Bank survey area. Only the contours necessary to show small features are maintained. The 1-m contours call attention to low-relief topographic complexity in areas of hummocky relief dominated by gravel deposits and small boulder ridges. Microtopography beyond the 1-m contour scale is not captured due to the resolution limitations of the multibeam echo sounder that collected the bathymetric data. Contours have been removed from areas where the seabed is relatively smooth and not dominated by gravel features. In relatively flat areas, 1-m contours produce incoherent patterns that misrepresent topographic complexity of the seabed. Contours that are evenly divisible by 5 that are represented in the previously published 5m contour dataset (Valentine and others, 1998) are also omitted. Bathymetric data from which these contours were derived were navigated with a differential global positioning system (DGPS) with an assumed accuracy within +/- 10 meters. The contours themselves were digitally derived from the bathymetric data gridded at a 13m cell size, which could introduce additional horizontal accuracy issues. Total horizontal accuracy is assumed to be within 10 meters. These data have been corrected for vessel motion (roll, pitch, heave, yaw) and tidal offsets, and referenced to mean lower low water. The manufacturer's reported vertical resolution of the Simrad EM-1000 multibeam echo sounder is 1% of water depth, which is less than 2 m given the depths within the study area (~25 to ~135 m). Data were corrected for tidal elevation using the NOAA Boston tide gauge. The contours were digitally derived from the bathymetric data. Initial data collection and processing is described in Valentine and others 1999, Valentine 2005, and Butman and others, 2007. A summary of that information is presented here. Surveying was conducted aboard the Canadian Hydrographic Service vessel Frederick G. Creed using a hull mounted multibeam echo sounder. These data were collected using a Simrad Subsea EM1000 operating at 95 kHz. SwathEd software (version unknown) developed by the Ocean Mapping Group, University of New Brunswick, was used to process the bathymetric and navigation data. The processing included editing the data to remove spurious points as well as incorporating tidal corrections. Processing took place between 1994 and 1996 by a variety of individuals. 1996 The remaining process steps are a function of incorporating information from the previous publications (noted in cross-references), along with processing notes maintained during data processing. The final SwathEd-produced grid at 10 meters per pixel was converted to an ASCII file using the University of New Brunswick script r4toASCII. The format of the ASCII file is latitude, longitude, and depth. The ASCII file was converted to an ArcInfo ungenerate format using a Perl script. The resulting format is ID, longitude, latitude, and negative depth. Each point has a unique ID value. Using ArcInfo 7.03, the ungenerate format was converted to a coverage format using the 'convert to arc' from 'generate tool' available in ArcTools. The 'build' command with the point option was then used to convert the data to a point coverage. This procedure generates the point locations stored in the ungenerate file but does not incorporate the depth values. To include depth, the ungenerate file - which has location as well as depth - was converted to an ArcInfo table, using 'Tables' in ArcInfo. The structure of the ArcInfo table was defined to include the ID, longitude, latitude, and depth in the appropriate format and size. Longitude and latitude were defined as floating point numbers with six decimal places, while depth was defined as a floating point number with two decimal places. To add the depth value to the point coverage, ArcInfo 'Tables' was used to join the point attribute table (pat) of the coverage to the newly-generated data table based on the ID value. In order to join the tables, the data table ID field had to be renamed to match the automatically assigned coverage ID field. The projection of the point coverage was defined in ArcInfo with the PROJECTDEFINE command and the following parameters: Projection Geographic; Datum NAD83; Units DD; Spheroid GRS80. This process was performed by Jessica Baker in 1997. Then the coverage was projected to the custom Mercator projection using the ArcInfo PROJECT command with the following options: Projection Mercator; Datum NAD83, Spheroid GRS1980; Units Meters; Longitude of Central Meridian -70degrees 19minutes; Latitude of true scale 41degrees 39minutes; False Easting 0; False northing 0. This process was performed by Jessica Baker in 1997. The final step was to convert the points to a grid. This was accomplished using the ArcInfo 'pointgrid' command. The depth attribute was gridded at a cell-size of 13 m, and the background value was set to nodata. This final processing step was performed in 1997, and is the basis for the subsequent work with contours. However, this process was repeated by Tammie Middleton in 2001 and is the grid presented in this data release. The 13-m cell-size was chosen because it reduced stripe artifacts in the data when processing with the SwathEd software. 1997 The original Mercator grid was projected to a geographic coordinate system using the ArcInfo PROJECT command. Once this was done, the Arc/Info routine lattice contour was used to generate the 1-m contours. Extensive editing was done with ArcEdit to remove contours from areas where the seabed is relatively smooth. Although each quadrangle was contoured independently, the contours were manually edited to remove "boundary faults". All editing work was done by Jessica Baker and Tanya Unger from 1997 to 1999. 1999 The 1-m coverage file was added to ArcMap 9.3.1. This dataset was then exported to a shapefile (arc2ctr1mtr_edt.shp). Portions of contours that were not necessary for the interpretation were deleted from the shapefile. This process step and the subsequent process steps were performed by the same person: VeeAnn A. Cross. 2013 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543 508-548-8700 x2251 508-457-2310 vatnipp@usgs.gov Within ArcGIS 10.8.1, the shapefile was incorporated into a file geodatabase with other datasets developed in this data release and additional trimming of the contours was performed as well as removing 0 value contours or contours with length 0. The geodatabase was in a custom Mercator projection which meant including the contours in that geodatabase required they be reprojected to match that coordinate system. The feature class was then exported as a shapefile in the geographic, NAD83 coordinate system. The attributes associated with the original coverage that were not necessary for the shapefile (such as FNODE, TNODE) were removed. 2023 Within QGIS 3.16.7-Hannover the Dissolve tool was used to combine the features of a given contour value into a single feature making each contour value a multipart polyline. 2023 Vector String 33 0.000001 0.000001 Decimal degrees D_North_American_1983 GRS_1980 6378137.0 298.257222101 Mean lower low water 1 meters Attribute values q3_1m_contours Portion of the 1-meter contours that fall within quadrangle 3 of the Stellwagen Bank study area. U.S. Geological Survey FID Internal feature number. Esri Sequential unique whole numbers that are automatically generated. Shape Feature geometry. Esri Coordinates defining the features. CONTOUR These values represent depth. The more negative the value, the deeper the water. Depths are relative to mean lower low water datum. U.S. Geological Survey -135 -26 meters U.S. Geological Survey - ScienceBase Mailing and Physical

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov The dataset contains the depth contours as a polyline shapefile (q3_1m_contours.shp and the shapefile components), a browse graphic (q3_1m_contours_browse.png) as well as FGDC CSDGM metadata in XML format. 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. Shapefile QGIS 3.16.7-Hannover The zip file contains the data in shapefile format, the browse graphic, and the associated CSDGM metadata. 4 https://www.sciencebase.gov/catalog/file/get/65d7c877d34ec3e1801d813e https://www.sciencebase.gov/catalog/item/65d7c877d34ec3e1801d813e https://doi.org/10.5066/P13PVHRI The first link downloads all data available from the page as a zip file, the second link is to the page containing the data, and the third link is to the data release main landing page. None. These data are available in shapefile format. The user must software capable of reading this format. The data are available for download in zip format. 20260402 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543 508-548-8700 x2251 508-457-2310 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with the USGS. FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998