Interpretation of the seabed geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts based on data collected by the U.S. Geological Survey from 1993-2019

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Title:
Interpretation of the seabed geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts based on data collected by the U.S. Geological Survey from 1993-2019
Abstract:
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 5, which is one of 18 similarly sized segments of the 3,700 square kilometer (km2) SBNMS region. The seabed of the SBNMS region is a glaciated terrain that is topographically and texturally diverse. Quadrangle 5 includes the shallow, rippled, coarse-grained sandy crest and upper eastern and western flanks of southern Stellwagen Bank, its fine-grained sandy lower western flank, and the muddy seabed in Stellwagen Basin. Water depths range from <25 m on the bank crest to ~100 m in the basin. The data presented here for quadrangle 5 are the foundation for Scientific Investigations Map 3515 (Valentine and Cross, 2024), 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. The maps of quadrangle 5 show the distribution of substrates across the southern part of Stellwagen Bank and the adjacent basins. Bathymetric and seabed backscatter imagery, photographs, video, and grain-size analyses were used to create the geologic interpretations presented here and have been reprocessed and released in segments to supports these interpretations. For the quadrangle 5 interpretations, data from 729 stations were analyzed, including 620 sediment samples. The seabed geology map of quadrangle 5 shows the distribution of 20 substrate types ranging from boulder ridges to mobile and rippled sand, to mud. Substrate types are defined or inferred through sediment grain-size composition, surface morphology, sediment layering, the mobility or immobility of substrate surfaces, and water depth range. Scientific Investigations Map 3515 portrays the major geological elements (substrates, topographic features, processes) of environments within quadrangle 5. It is intended to be a basis for the study of sediment transport processes that affect a shallow, offshore bank, for the study of the ecological requirements of invertebrate and vertebrate species that use these substrates, and to support seabed management in the region.
Supplemental_Information:
This interpretation is based on multibeam sonar bathymetry, multibeam backscatter imagery, video, photos, and grain-size analyses of samples collected from the seabed in the time period 1993-2019. Over 50 scientific cruises have been conducted in an effort to map Stellwagen Bank. For this interpretation of Quadrangle 5 on Stellwagen Bank, ground-truth stations on the following 23 USGS WHCMSC field activities have played a vital role: 1993-006-FA, 1993-023-FA, 1993-030-FA, 1994-004-FA, 1994-014-FA, 1995-012-FA, 1995-015-FA, 1995-036-FA, 1996-025-FA, 1996-037-FA, 1996-038-FA, 1998-017-FA, 1998-022-FA, 1998-029-FA, 1999-011-FA, 2013-044-FA, 2014-015-FA, 2014-055-FA, 2014-066-FA, 2015-017-FA, 2015-062-FA, 2016-038-FA, 2019-008-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=1993-023-FA.
  1. How might this data set be cited?
    Valentine, Page C., 20240320, Interpretation of the seabed geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts based on data collected by the U.S. Geological Survey from 1993-2019: data release DOI:10.5066/P9W9BN3S, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Valentine, Page C., and Cross, VeeAnn A., 2024, Geospatial datasets of seabed topography, sediment mobility, and the distribution of geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: data release DOI:10.5066/P9W9BN3S, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2024, Geospatial datasets of seabed topography, sediment mobility, and the distribution of geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: U.S. Geological Survey data release, https://doi.org/10.5066/P9W9BN3S.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.41111
    East_Bounding_Coordinate: -70.22222
    North_Bounding_Coordinate: 42.32222
    South_Bounding_Coordinate: 42.20278
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/63a09167d34e0de3a1f27731?name=q5_substrate_interp_browse.png&allowOpen=true (PNG)
    Thumbnail image showing the interpreted bottom substrates within quadrangle 5 of the Stellwagen Bank National Marine Sanctuary. The image indicates the four different representation of the seabed interpretation including the geologic substrates, the sediment mobility, substrate coarseness, and substrate mud content.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1993
    Ending_Date: 2019
    Currentness_Reference:
    ground condition of original data upon which the interpretation is based
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Vector Digital Dataset (Polygon)
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (73)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_North_American_1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    q5_geol_interp
    Interpreted substrate polygons of quadrangle 5 located in the Stellwagen Bank National Marine Sanctuary region. (Source: U.S. Geological Survey)
    OBJECTID
    Internal feature number. (Source: Esri)
    Range of values
    Minimum:1
    Maximum:73
    Sub_Unit_S
    Substrate Unit Symbol abbreviation corresponding to the geologic substrate ("geo_substr") name. (Source: U.S. Geological Survey)
    ValueDefinition
    A1Abbreviated symbol for A1 r_cgS where r = rippled, cgS = coarse-grained sand
    A3Abbreviated symbol for A3 r_cgS where r = rippled, cgS = coarse-grained sand
    BAbbreviated symbol for B r_cgS / i_cbG where r = rippled, cgS = coarse-grained sand, / = overlying, or partial veener over, i = immobile, c = cobble, b = boulder, G = gravel
    CAbbreviated symbol for C i_cbG where i = immobile, c = cobble, b = boulder, G = gravel
    HAbbreviated symbol for H r_fgS where r = rippled, fgS = fine-grained sand
    IAbbreviated symbol for I i_fgcgS where i = immobile, fgcgS = fine- and coarse-grained sand
    JAbbreviated symbol for J r_cgfgS / i_pcbG where r = rippled, cgfgS = coarase- and fine-grained sand, / = overlying, or partial veener over, i = immobile, p = pebble, c = cobble, b = boulder, G = gravel
    KAbbreviated symbol for K r_cgS where r = rippled, cg = coarse-grained, s = sand
    LAbbreviated symbol for L i_mfgS where i = immobile, m = muddy, fgS = fine-grained sand
    MAbbreviated symbol for M i_mcgS / pcbG where i = immobile, m = muddy, cgS = coarse-grained sand, / = overlying, or partial veener over, p = pebble, c = cobble, b = boulder, G = gravel
    PAbbreviated symbol for P i_mfgS where i = immobile, m = muddy, fgS = fine-grained sand
    QAbbreviated symbol for Q i_mfgS / pcbG where i = immobile, m = muddy, fgS = fine-grained sand, / = overlying, or partial veener over, p = pebble, c = cobble, b = boulder, G = gravel
    RAbbreviated symbol for R i_fgsM where i = immobile, fgS = fine-grained sand, M = mud
    SAbbreviated symbol for S i_M where i = immobile, M = mud
    TAbbreviated symbol for T i_mcgS / pcbG where i = immobile, m = muddy, cgS = coarse-grained sand, / = overlying, or partial veener over, p = pebble, c = cobble, b = boulder, G = gravel
    UAbbreviated symbol for U i_pcG where i = immobile, p = pebble, c = cobble, G = gravel
    VAbbreviated symbol for V i_fgsM / cbG where i = immobile, fgS = fine-grained sandy, M = mud, / = overlying, or partial veener over, c = cobble, b = boulder, G = gravel
    geo_substr
    Geologic substrate unit name that designates a unique substrate area on the seabed of quadrangle 5. These definitions include all substrates present in quadrangle 5, including the ones that are not mappable as separate polygons in the shapefile, but are referenced in other definitions so included here. (Source: U.S. Geological Survey)
    ValueDefinition
    A1 r_cgSRippled, coarse-grained sand. Substrate A1 is a mobile, coarse-grained sand deposit that lies on the crest and upper western flank of Stellwagen Bank in quadrangle 5. Substrate A1 is very widespread on the bank. It also occurs on the eastern flank of the bank in quadrangle 6 (Valentine and Gallea, 2015) to the east and on the southwestern and southeastern flanks of the bank in quadrangle 2 and quadrangle 3, respectively. The irregular, digitated margin of the downslope edge of A1 in quadrangle 5 suggests that the substrate there represents a sheet of sand that was transported westward onto the western flank from the bank crest. The nature of transport is not known. Water depth range of the stations is 24 to 53 m and of the mapped substrate 24 to 55 m. Substrate A1 is equivalent to the upper mobile layer of substrate B which lies within the region occupied by substrate A1. Grain-size analyses of all samples identified as substrate A1 were used to calculate the mean weight percents of aggregates and composite grades: mud, less than 1; sand, 94 (fgS, 3; cgS, 90); gravel, 6 (G1, 5; G2, 1). Substrate A1 is dominantly coarse-grained sand and is very low in mud and fine-grained sand content. Its surface is covered with storm-generated sand ripples with wavelengths of 0.5 to 1.0 m, and the orientation of ripple crests varies from N-S to NW-SE. The ripples are symmetrical and well-shaped (sometimes with narrow, sharply-defined crests and sometimes with broad crests hosting secondary ripples) when first formed by storm wave currents, but subsequently are rounded by faunal disturbance and flattened by bottom-tending fishing gear such as dredges and trawls. These relatively large bedforms are not discernible in multibeam topographic imagery. Substrate A1 is similar to substrate A3 in its mud and sand content and lies at similar water depths. However, substrate A3 contains much more fine-grained sand (22 weight percent). Each sample from A3 generally contains 10 weight percent or more of fine-grained sand, mostly as 3 phi sand, and its surface is covered with smaller ripples.
    A3 r_cgSRippled, coarse-grained sand. Substrate A3 is a collection of mobile, coarse-grained sand deposits that lies on the crest and upper western flank of Stellwagen Bank. Water depth range of the stations is 23 to 53 m. Grain-size analyses of all samples identified as A3 were used to calculate the mean weight percents of aggregates and composite grades: mud, less than 1; sand, 98 (fgS, 22; cgS, 76); gravel, 1 (G1, 1; G2 <1). Substrate A3 is similar to substrate A1 in being a coarse-grained sand and having a very low mud content. It differs from A1 in having much more fine-grained sand (22 weight percent), mostly as 3 phi sand, and its surface ripples are much smaller, with wavelengths of 10 to 20 cm. Substrate A3 is also similar to substrate A2, which lies on the far eastern flank of the bank in quadrangle 6 (Valentine and Gallea, 2015). They both contain more fine-grained sand than substrate A1, but A2 is immobile and has less fine-grained sand than A3, and it lies at deeper water depths (53-77 m). In quadrangle 5, substrate A3 occurs in large and small deposits, and most are not mappable as coherent units at the present scale. Some form irregular hummocks that are visible in bathymetric imagery; and deposits of substrate A1 occur between the hummocks. Deposits of substrate A3 also occur intermittently along the deep western edge of substrate A1. Substrate A3 deposits are texturally equivalent to substrate K, which lies at deeper depths, but A3 deposits are geographically separated from substrate K by substrate H. The largest deposit of A3 occurs in an area of hummocky seabed (observed in multibeam topographic imagery) on the bank crest within a provisional, straight-sided polygon. Some stations that represent substrate A1 occur within this A3 polygon.
    B r_cgS / i_cbGRippled, coarse-grained sand; partial veneer on immobile cobble, boulder gravel. Substrate B is a layered substrate of mobile, coarse-grained sand partially overlying the margins of immobile cobble, boulder gravel features (gravel mounds, boulder ridges) in small areas surrounded by substrate A1 on the crest and upper eastern flank of Stellwagen Bank. Sixteen provisional, straight-sided polygons centered on gravel features show the approximate distribution of substrate B. Water depth range of the mapped substrate is 30 to 44 m. The rippled, coarse-grained sand upper layer of substrate B is equivalent to substrate A1. For mean weight percents of aggregates and composite grades of this upper layer of substrate B, see substrate A1. The substrate also occurs on the eastern flank of the bank in adjacent quadrangle 6 (Valentine and Gallea, 2015). The gravel features of substrate B are identified based on multibeam topographic imagery and video and photographic imagery.
    C i_cbGImmobile, cobble, boulder gravel. Substrate C is immobile gravel that forms topographic ridges where cobbles and boulders are piled upon one another and are separated by voids. Water depth range of the mapped substrate is 30 to 65 m. It is identified on the basis of video and photographic images of mapped topographic ridges (Valentine, 2005) and is shown as boulder ridges less than 1 m and ≥1 m high. It is present in three areas in quadrangle 5: on the upper eastern flank and crest of Stellwagen Bank where it occurs with substrate B; on Western Spur where it occurs with substrate L; and on Southwestern Spur where it occurs with substrate Q. Substrate C occurs more commonly in adjacent quadrangle 6 on the eastern flank of Stellwagen Bank and on the tops of the Ninety Meter Banks (Valentine and Gallea, 2015).
    H r_fgSRippled, fine-grained sand. Substrate H is a mobile, fine-grained sand deposit that lies on the lower western flank of Stellwagen Bank in the southern part of quadrangle 5. Water depth range of the stations is 38 to 52 m and of the mapped substrate 35 to 52 m. Mean weight percents of aggregates and composite grades: mud, 2; sand, 98 (fgS, 83; cgS, 15); gravel, less than 1 (G1, <1; G2, 0). Substrate H extends southward into quadrangle 2. The surface of substrate H is characterized by low, long-wavelength (approximately 40 to 50 m) ripples that are visible in bathymetric imagery and as depicted by 1-m contours; shell deposits are present in ripple troughs. Because this rippled, fine-grained sand substrate is bounded upslope to the east by the rippled, coarse-grained sand of substrate A1 (which appears to override it from the east) and downslope to the west by rippled, coarse-grained sand of substrate K; and because substrate H has an irregular southwestern edge where it abuts substrate K; it is likely that substrate H represents a fine-grained sand sheet that has moved downslope and overridden the upslope part of K. Substrate H now separates two coarse-grained sand substrates (A1 and K). This suggests that the long-wavelength ripples that form the surface of substrate H are relict and that the substrate may not be mobile at present. The timing of these postulated mass movements is not known. Part of substrate H is bounded downslope to the west by substrate L, which it resembles in the ratio of fine- to coarse-grained sand content, but H contains less mud L. Some stations that occur in the area occupied by substrate H represent deposits of substrate A1 that are not mappable at the present scale and are shown by a symbol and the number 0.
    I i_fgcgSImmobile, fine- and coarse-grained sand. Substrate I is an immobile fine- and coarse-grained sand deposit. It forms a hummocky surface on the lower western flank of Stellwagen Bank. Water depth range of the stations is 44 to 71 m and of the mapped substrate 40 to 75 m. Mean weight percents of aggregates and composite grades: mud, 7; sand, 92 (fgS, 42; cgS, 49); gravel, 1 (G1, 1; G2, <1). It is bounded to the east in shallower water by substrate A1, to the south by substrates H and L, to the north by substrate L, and to the west by substrate R. Substrate I is similar in grain-size content to the upper layer of substrate J, which it surrounds. The hummocky surface of substrate I is visible in multibeam topographic imagery and as depicted by 1-m contours, and its digitated southwestern margin is similar to the topography of the adjacent western margin of substrate A1. These features suggest that substrate I represents an older coarse-grained sand sheet (not unlike A1) now overlain by a thin layer of fine-grained sand not unlike adjacent substrates H and L.
    J r_cgfgS / i_pcbGRippled, coarse- and fine-grained sand; partial veneer on immobile pebble, cobble, boulder gravel. Substrate J is a layered substrate of mobile, coarse- and fine-grained sand that partially covers immobile pebble, cobble, boulder gravel in a depression surrounded by substrate I on the lower western flank of Stellwagen Bank. Water depth range of the stations is 48 to 55 m and of the mapped substrate 46 to 59. Mean weight percents of aggregates and composite grades of the sediment partial veneer overlying gravel: mud, 4; sand, 92 (fgS, 47; cgS, 45); gravel, 4 (G1, 2; G2, 2). Substrate J lies in an area of multibeam high backscatter values centered on ~42 degrees 15.5 minutes North and ~70 degrees 19.6 minutes West. The upper layer of substrate J is similar to substrate I in mud, sand, and gravel content.
    K r_cgSRippled, coarse-grained sand. Substrate K is a mobile, coarse-grained sand deposit that lies on the lower flank of Stellwagen Bank southeast of the eastern end of Southwestern Spur. Water depth range of the stations is 42 to 50 m and of the mapped substrate 40 to 50 m. Mean weight percents of aggregates and composite grades: mud, 1; sand, 98; (fgS, 24; cgS, 75); gravel, less than 1 (G1, <1; G2, 0). Substrate K is dominantly coarse-grained sand and is low in mud, but it contains an appreciable amount of fine-grained sand (3 phi sand is more abundant than 4 phi sand). It is texturally equivalent to substrate A3. To the northeast and east, substrate K is bounded by substrate H, whose digitated boundary, based on multibeam topographic imagery, suggests it has encroached upon substrate K during a mass movement event. To the west, in deeper water, substrate K is bounded by substrate L. Thus, substrate K, a coarse-grained sand, lies between fine-grained sand substrates H and L, indicating that K was not deposited by present-day sedimentary transport processes, and its depositional history is unclear.
    L i_mfgSImmobile, muddy, fine-grained sand. Substrate L is an immobile, muddy, fine-grained sand deposit that is present in three areas on the lowermost western flank of Stellwagen Bank and on the eastern part of Western Spur. Water depth range of the stations is 50 to 77 m and of the mapped substrate 44 to 77m. Mean weight percents of aggregates and composite grades: mud, 10; sand, 89 (fgS 73; cgS, 17); gravel, 1 (G1, 1; G2, 0). It lies in a region where mud content (range 2-33 weight percent) increases with increase in water depth from bank to basin. Substrate L in quadrangle 5 is texturally equivalent to substrate G1 that occurs off the eastern flank of Stellwagen Bank in quadrangle 6 (Valentine and Gallea, 2015), but substrate G1 lies in much deeper water (85-171 m). Some stations that occur in the areas occupied by substrate L represent substrates that are not mappable at the present scale and are represented on maps by a symbol. See Valentine and Cross, 2024 for additional description of this unit.
    M i_mcgS / pcbGImmobile, muddy, coarse-grained sand; partial veneer on pebble, cobble, boulder gravel. Substrate M is a layered substrate of immobile, muddy, coarse-grained sand that partially covers pebble, cobble, boulder gravel. It forms the hummocky surface of the western part of Western Spur, a westward extension of Stellwagen Bank into Stellwagen Basin. Water depth range of the stations is 59 to 68 m and of the mapped substrate 56 to 69 m. Mean weight percents of aggregates and composite grades of the sediment partial veneer overlying gravel: mud, 22; sand, 73 (fgS, 13; cgS, 60); gravel, 5 (G1, 4; G2, 1). The upper layer of substrate M is dominantly coarse-grained sand with less fine-grained sand (3 phi sand is greater than 4 phi sand) and mud. The irregular surface of the substrate indicates the presence of partially-buried gravel features that are visible in multibeam topographic imagery and as depicted by 1-m contours. The upper layer of substrate M resembles somewhat the upper layer of substrate Q, which forms the hummocky surface of Southwestern Spur to the south. The upper layer of substrate Q has a similar mud content (24 weight percent), but unlike substrate M, it is a muddy, fine-grained sand. Substrate M is bounded in shallower water to the east by substrate L (mud content 10 weight percent) and in deeper water to the west by substrate T (mud content 34 weight percent) on the flank of Western Spur.
    N i_mcgSImmobile, muddy, coarse-grained sand. Substrate N is an immobile, muddy, coarse-grained sand deposit that is associated with substrates L and O in an area of hummocky topography east of the scarp that separates the base of Stellwagen Bank from Stellwagen Basin. Water depth range of the stations is 58 to 65 m. Grain-size analyses of all samples identified as N were used to calculate the mean weight percents of aggregates and composite grades: mud, 11; sand, 73 (fgS, 10; cgS, 63); gravel, 15 (G1, 10; G2, 5). See the description of substrate L with which both substrates N and O are associated. Stations identified as deposits of substrate N occur in the area occupied by substrate L, but they are not mappable as a coherent unit at the present scale so not present as a separate polygon.
    O i_mfgcgSImmobile, muddy, fine- and coarse-grained sand. Substrate O is an immobile, muddy, fine- and coarse-grained sand deposit that is associated with substrates L and N in an area of hummocky topography east of the scarp that separates the base of Stellwagen Bank from Stellwagen Basin. Water depth range of the stations is 55 to 64 m. Grain-size analyses of all samples identified as O were used to calculate the mean weight percents of aggregates and composite grades: mud, 15; sand, 82 (fgS, 41; cgS, 41); gravel, 4 (G1, 4; G2, 0). Substrate O likely is a mixture of substrates L and N. See the description of substrate L with which both substrates N and O are associated. Stations identified as deposits of substrate O occur in the area occupied by substrate L, but they are not mappable as a coherent unit at the present scale so not present as a separate polygon.
    P i_mfgSImmobile, muddy, fine-grained sand. Substrate P is an immobile, muddy, fine-grained sand deposit that lies at the base of Stellwagen Bank in two areas of Stellwagen Basin, north and south of Southwestern Spur. Water depth range of the stations and the mapped substrate is 59 to 69 m. Mean weight percents of aggregates and composite grades: mud, 29; sand, 69 (fgS, 60; cgS, 10); gravel, 1 (G1, 1; G2, <1). The two areas of substrate P are separated by substrate Q, a layered, muddy, fine-grained sand that partially covers pebble, cobble, and boulder gravel on Southwestern Spur. Substrate P (mud content 29 weight percent) is very similar texturally to the upper layer of substrate Q (mud content 24 weight percent). Although mud content of both is almost equal, and both are dominated by fine-grained sand, the upper layer of Q overlies gravel and contains more coarse-grained sand than P. Substrate P has a greater mud content than substrate L (10 weight percent) that lies in shallower water to the east but much less than substrate R (58 weight percent) that lies in deeper water to the west. As mud content increases westward from substrates L to P to R (from the base of the bank into the basin), fine-grained sand content decreases, especially the 3-phi sand. The somewhat hummocky surface of substrate P, as observed in multibeam topographic imagery, where it borders Southwestern Spur indicates the presence of buried gravel features that are exposed in substrate Q on the spur.
    Q i_mfgS / pcbGImmobile, muddy, fine-grained sand; partial veneer on pebble, cobble, boulder gravel. Substrate Q is a layered substrate of immobile, muddy, fine-grained sand that partially covers pebble, cobble, boulder gravel. It forms the hummocky surface of Southwestern Spur, an elongate feature that extends northwestward into Stellwagen Basin from the lower southwestern flank of Stellwagen Bank. Water depth range of the stations is 54 to 73 m and the substrate 49 to 81 m. Mean weight percents of aggregates and composite grades of the sediment partial veneer overlying gravel: mud, 24; sand, 69 (fgS, 42; cgS, 26); gravel, 7 (G1, 4; G2, 3). The deeper parts of substrate Q in the west are bounded by mud substrates S (mud content 94 weight percent) and R (mud content 58 weight percent), while the shallower parts in the east are bounded by substrates L (mud content 10 weight percent) and P (mud content 29 weight percent). The upper layer of substrate Q is dominantly fine-grained sand (3 phi sand is greater than 4 phi sand); mud and coarse-grained sand are present in equal amounts. The irregular surface of boulder ridges and of partly-buried gravel features is visible in multibeam topographic imagery and as depicted by 1-m contours.
    R i_fgsMImmobile, fine-grained sandy mud. Substrate R is an immobile, fine-grained sandy mud deposit that occupies two areas in Stellwagen Basin: one adjacent to the southern margin of Southwestern Spur, and the other along the base of the western flank of Stellwagen. Water depth range of the stations is 71 to 88 m and the mapped substrate 67 to 88 m. Substrate R is equivalent to the upper layer of substrate V, which it surrounds. Mean weight percents of aggregates and composite grades of the fine-grained sandy mud: mud, 58; sand, 42 (fgS, 38; cgS, 3); gravel, less than 1 (G1, <1; G2, 0). Substrate R is bounded by sand substrates with lower mud content (I, L, P, and Q) that lie in shallower water on the lower western flank of Stellwagen Bank and on the flanks of Southwestern Spur and Western Spur. It is bounded in a deeper part of Stellwagen Basin by substrate S with a higher mud content. Substrate R is characterized by the presence of fish and crab burrows.
    S i_MImmobile mud. Substrate S is an immobile mud deposit that occupies much of Stellwagen Basin. Water depth range of the stations is 82 to 103 m and the mapped substrate 82 to 105 m. Mean weight percents of aggregates and composite grades: mud, 94; sand, 6 (fgS, 5; cgS 1); gravel, 0. Substrate S is bounded to the east along the basin margin by substrate R (mud content 58 weight percent). Elsewhere, substrate S is bounded to the south by substrate Q (upper layer mud content 24 weight percent) on Southwestern Spur, and to the north by substrate T (upper layer mud content 34 weight percent) on the flanks of Fifteen Bank and Western Spur. Substrate S is characterized by the presence of fish and crab burrows.
    T i_mcgS / pcbGImmobile, muddy, coarse-grained sand; partial veneer on pebble, cobble, boulder gravel. Substrate T is a layered substrate of immobile, muddy, coarse-grained sand that partially covers pebble, cobble, boulder gravel. It forms a somewhat hummocky seabed on the top and flanks of Fifteen Bank and on the westward-facing flank of the adjacent Western Spur. Water depth range of the stations and the mapped substrate is 70 to 103 m. Mean weight percents of aggregates and composite grades of the sediment partial veneer overlying gravel: mud, 34; sand, 52 (fgS, 14; cgS, 37); gravel, 14 (G1, 10; G2, 4). The substrate resembles substrate M, but substrate T has a somewhat higher mud content.
    U i_pcGImmobile, pebble, cobble gravel. Substrate U is an immobile, gravel pavement. Video imagery revealed it to be closely-packed pebbles and cobbles with little or no sand veneer that lies on the Western Edge of Stellwagen Bank. Water depth of the single station is 62 m. Weight percents of aggregates and composite grades collected from this station: mud, 10; sand, 44 (fgS, 11; cgS, 33); gravel, 46 (G1, 10; G2, 36). The sample is a mixture of the gravel pavement that forms the seabed (cobbles were observed but not collected) and the underlying sandy sediment. Based on multibeam topographic and backscatter imagery, the substrate extends northward along the Western Edge into the southern part of quadrangle 8. A station identified as a deposit of substrate U (1646, 35 m) in the area occupied by substrate A1 is not mappable as a coherent unit at the present scale; it lies in an area of high backscatter values centered on ~42 degrees 19.3 minutes North and ~70 degrees 18.6 minutes West that likely represents a gravel pavement.
    V i_fgsM / cbGImmobile, fine-grained sandy mud; partial veneer on cobble, boulder gravel. Substrate V is a layered substrate of immobile, fine-grained sandy mud that partially covers cobble, boulder gravel that is surrounded by substrate R in two areas in Stellwagen Basin. Water depth range of the stations and the mapped substrate is 72 to 82 m. The upper layer of substrate V is texturally equivalent to substrate R. Mean weight percents of aggregates and composite grades of the sediment partial veneer overlying gravel: mud, 68; sand, 32 (fgS, 30; cgS, 2); gravel, 0 (G1, 0; G2, 0). The underlying cobbles and boulders represent the tops of almost-buried mounds of gravel that produce a hummocky surface that is visible in multibeam topographic imagery and as depicted by 1-m contours. The cobbles and boulders are exposed in depressions that are interpreted to be formed by the scouring activities of large fish observed to occupy them in video imagery.
    W r_cgS / i_scMRippled, coarse-grained sand; partial veneer on immobile, semiconsolidated mud. Substrate W is a layered substrate of rippled, coarse-grained sand that partially covers outcrops of semiconsolidated mud that occurs in the area occupied by substrate A1. It was observed at 3 locations on the bank crest in quadrangle 5. Water depth range of the stations is 31 to 35 m. Grain-size analyses of all samples identified as W were used to calculate the mean weight percents of aggregates and composite grades of the sediment partial veneer overlying semiconsolidated mud: mud, less than 1; sand, 88 (fgS, 10; cgS, 78); gravel, 12 (G1, 11; G2, 1). Visual analysis of video imagery revealed the lower substrate to be an irregular, burrowed and fragment-strewn surface. It is interpreted to represent an outcrop of semiconsolidated mud that has been burrowed by benthic organisms. The rippled, coarse-grained sand partial upper layer was collected without disturbing the lower clay layer and is texturally very similar to substrates A1 and A3. Stations identified as deposits of substrate W in the area occupied by substrate A1 are not mappable as a coherent unit at the present scale so not present as a separate polygon.
    geo_descr
    Brief text description corresponding to the geologic substrate attribute "geo_substr". (Source: U.S. Geological Survey) Character set (text) not to exceed the 255 character limit of a shapefile attribute.
    substr_mob
    Substrate mobility interpreted unit based on the presence of sand ripples observed in video and photographic imagery. (Source: U.S. Geological Survey)
    ValueDefinition
    boulder ridges <1 meter in heightRidges less than 1 meter in height equivalent to substrate C.
    boulder ridges >=1 meter in heightRidges greater than or =1 meter in height equivalent to substrate C.
    immobile sedimentSand (substrate I), muddy sand (substrates L, N, O and P), sandy mud (substrate R), mud (substrate S), muddy sand partial veneer on gravel (substrates M, Q, and T), sandy mud partial veneer on gravel (substrate V), and gravel pavement (substrate U)
    mobile and immobile sedimentRippled sand partial veneer on immobile pebble, cobble and boulder gravel (substrates B and J), and rippled sand partial veneer on immobile semiconsolidated mud (substrate W)
    mobile sedimentRippled sand; equivalent to substrates A1, A3, H, and K.
    mob_descr
    Text description corresponding to the substrate mobility attribute "substr_mob". (Source: U.S. Geological Survey) Character set (text).
    sub_grain
    Substrate grain size interpreted unit based on the mean weight percent of the sand fraction. (Source: U.S. Geological Survey)
    ValueDefinition
    boulder ridges <1 meter in heightBoulder ridges <1 meter in height equivalent to substrate C.
    boulder ridges >=1 meter in heightBoulder ridges >=1 meter in height equivalent to substrate C.
    dominated by coarse-grained sand in the sand fractionCoarse-grained sand and muddy coarse-grained sand in which coarse-grained sand (0, 1, and 2 phi combined) constitutes the largest portion of the sand fraction; equivalent to substrates A1, A3, B, K, M, N, T and W.
    dominated by fine-grained sand in the sand fractionFine-grained sand, muddy fine-grained sand, and fine-grained sandy mud in which fine-grained sand (3 and 4 phi combined) constitutes the largest portion of the sand fraction; equivalent to substrates H, L, P, Q, R and V.
    dominated by mud with a low weight percent sandSediment which is 94 weight percent mud (>4 phi), 5 percent fine-grained sand, and 1 percent coarse-grained sand; equivalent to substrate S.
    gravel pavementGravel pavement; equivalent to substrate U.
    fine- and coarse-grained sandSediment in which fine- and coarse-grained sand contents differ by <=7 weight percent; equivalent to substrates I, J, and O.
    grain_desc
    Text description corresponding to the substrate grain size "sub_grain". (Source: U.S. Geological Survey) Character set (text).
    substr_mud
    Substrate mud content interpreted unit based on the mean weight percent of mud content. (Source: U.S. Geological Survey)
    ValueDefinition
    < 1Mud content < 1 mean weight percent; equivalent to substrates A1, A3, B and W.
    1 to <5Mud content 1 to less than 5 mean weight percent; equivalent to substrate I.
    5 to <10Mud content 5 to less than 10 mean weight percent, equivalent to substrate I.
    10 to <20Mud content 10 to less than 20 mean weight percent; equivalent to substrates L, N and O.
    20 to <50Mud content 20 to less than 50 mean weight percent; equivalent to substrates M, P, Q and T.
    50 to <90Mud content 50 to less than 90 mean weight percent; equivalent to substrates R and V.
    >90Mud content greater than 90 mean weight percent; equivalent to substrate S.
    boulder ridges <1 meter in heightBoulder ridges were never sampled due to the nature of the ridges, so are not represented by a measured mud weight percent.
    boulder ridges >=1 meter in heightBoulder ridges were never sampled due to the nature of the ridges, so are not represented by a measured mud weight percent.
    gravel pavementEquivalent to substrate U. The mud content is likely part of the mixed sediment underlying the gravel, and therefore the substrate is mapped as a gravel pavement and is not assigned to a mud content category
    mud_descr
    Text description corresponding to the substrate mud content "substr_mud". (Source: U.S. Geological Survey) Character set (text).
    Area_km2
    The area of the polygon, in square kilometers, calculated using the custom Mercator projection specified in the process step. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.001435
    Maximum:97.424322
    Units:square kilometers
    Entity_and_Attribute_Overview:
    The geo_substr attribute definitions come from the related report (Valentine and Cross, 2024). In the geo_substr attribute, weight percents described in the domain value definitions may not add to 100 due to rounding of values. Also in the geo_substr attributes, the mean weight percents for the units, sand is divided into two composite grades: fine-grained sand (fgS; 0.062 to <0.25 mm) and coarse-grained sand (cgS; 0.25 to <2mm). Gravel is also divided into two composite grades: Gravel1 (G1; 2 to <8 mm) and Gravel2(G2; 8 to <64 mm). This G1 and G2 are not to be confused with the geologic substrate units G1 i_mfgS and G2 i_mfgS in quadrangle 6. These G1 and G2 are presented in the related report (Valentine and Cross, 2024) as subscripts 1 and 2.
    The definitions of the substrate components are fully defined in the related report (Valentine and Cross, 2024) but are also defined here:
    i = immobile
    cgS = coarse-grained sand
    fgS = fine-grained sand
    fgcgS = fine- and coarse-grained sand dominated by fine-grained
    cgfgS = coarse-and fine-grained sand dominated by coarse-grained
    If the S is capitalized, it indicates Sand as a major component. A lower-case s indicates sandy, and not a major component.
    M = mud (as a major component)
    m = muddy
    r = rippled
    p = pebble
    c = cobble (when not immediately followed by g)
    b = boulder
    G = gravel (as a major component)
    g = gravelly
    / = overlying or partial veneer over
    Entity_and_Attribute_Detail_Citation: Page Valentine, U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Page C. Valentine
  2. Who also contributed to the data set?
    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.
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2239 (voice)
    508-457-2310 (FAX)
    whsc_data_contact@usgs.gov
    Contact_Instructions:
    The metadata contact email address is a generic address in the event the person is no longer with the USGS.

Why was the data set created?

This dataset provides comprehensive seabed interpretations of the seafloor within quadrangle 5 of the Stellwagen Bank National Marine Sanctuary. This interpretation includes the geologic substrates, sediment mobility, substrate coarseness, and substrate mud content. The geologic substrates it the primary interpretation with the remaining three representations derivatives of that.

How was the data set created?

  1. From what previous works were the data drawn?
    DS469 (source 1 of 12)
    Valentine, Page C., Gallea, Leslie B., Blackwood, Dann S., and Twomey, Erin R., 2010, Seabed photographs, sediment texture analyses, and sun-illuminated sea floor topography in the Stellwagen Bank National Marine Sanctuary region off Boston, Massachusetts: Data Series 469, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital online
    Source_Contribution:
    Original photographic imagery and sediment grain size analyses were used to interpret the seabed geology of the study area.
    SIM2840 (source 2 of 12)
    Page C. Valentine, editor, 2005, Sea floor image maps showing topography, sun-illuminated topography, backscatter intensity, ruggedness, slope, and the distribution of boulder ridges and bedrock outcrops in the Stellwagen Bank National Marine Sanctuary region off Boston, Massachusetts: Scientific Investigations Map 2840, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: DVD-ROM and online
    Source_Contribution:
    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 of the seabed geology of the study area.
    video (source 3 of 12)
    U.S. Geological Survey, Unpublished Material, Bottom Video.

    Type_of_Source_Media: Hi-8 video tape and digital video (for years 1993 to 2019)
    Source_Contribution:
    Original video imagery of the seabed was used to interpret the seabed geology of the study area. Although the video has not been released due to size constraints, the tracklines of video acquisition are available from numerous releases. Those used in Quadrangle 5 are listed as additional source contributions.
    2013-044-FA video lines (source 4 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2019, Sea-floor Sediment Samples, Seabed Imagery, and CTD Instrument Data Collected on Stellwagen Bank in November, 2013, U.S. Geological Survey Field Activity 2013-044-FA: data release DOI:10.5066/P9N8YJL1, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2019, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in November, 2013, U.S. Geological Survey Field Activity 2013-044-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9N8YJL1.
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset is the location of the video transects from field activity 2013-044-FA (those that fall within quadrangle 5) that were used in the interpretation.
    2014-015-FA video lines (source 5 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Sea-Floor Sediment Samples, Seabed Imagery, and CTD Instrument Data Collected on Stellwagen Bank in May, 2014, U.S. Geological Survey Field Activity 2014-015-FA: data release DOI:10.5066/P93OZR8C, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in May, 2014, U.S. Geological Survey Field Activity 2014-015-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P93OZR8C.
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset is the location of the video transects from field activity 2014-015-FA (those that fall within quadrangle 5) that were used in the interpretation.
    2014-055-FA video lines (source 6 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Sea-Floor Sediment Samples, Seabed Imagery, and CTD Instrument Data Collected on Stellwagen Bank in September, 2014, U.S. Geological Survey Field Activity 2014-055-FA: data release DOI:10.5066/P9NK9AJP, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in September, 2014, U.S. Geological Survey Field Activity 2014-055-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9NK9AJP.
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset is the location of the video transects from field activity 2014-055-FA (those that fall within quadrangle 5) that were used in the interpretation.
    2014-066-FA video lines (source 7 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Sea-Floor Sediment Samples, Seabed Imagery, and CTD Instrument Data Collected on Stellwagen Bank in November, 2014, U.S. Geological Survey Field Activity 2014-066-FA: data release DOI:10.5066/P9EQM8MK, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in November, 2014, U.S. Geological Survey Field Activity 2014-066-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9EQM8MK.
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset is the location of the video transects from field activity 2014-066-FA (those that fall within quadrangle 5) that were used in the interpretation.
    2015-017-FA video lines (source 8 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in May and June, 2015, U.S. Geological Survey Field Activity 2015-017-FA: data release DOI:10.5066/P9BG490P, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in May and June, 2015, U.S. Geological Survey Field Activity 2015-017-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9BG490P .
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset is the location of the video transects from field activity 2015-017-FA (those that fall within quadrangle 5) that were used in the interpretation.
    2015-062-FA data (source 9 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2017, Sea floor sediment samples, seabed imagery, and CTD data collected in Stellwagen Bank National Marine Sanctuary, MA in 2015, U.S. Geological Survey Field Activity 2015-062-FA: data release DOI:10.5066/F7N015FS, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C. and Cross, V.A., 2017, Sea floor sediment samples, seabed imagery, and CTD data collected in Stellwagen Bank National Marine Sanctuary, MA in 2015, U.S. Geological Survey Field Activity 2015-062-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7N015FS .
    Type_of_Source_Media: digital file (point shapefile and polyline shapefile)
    Source_Contribution:
    This dataset contains the location of the video transects from field activity 2015-062-FA (those that fall within quadrangle 5) that were used in the interpretation. Additionally, the publication has sediment sample information used in the interpretation.
    2016-038-FA video lines (source 10 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Station Information, Seabed and Sample Imagery, and CTD Instrument Data Collected on Stellwagen Bank in September, 2016, U.S. Geological Survey Field Activity 2016-038-FA: data release DOI:10.5066/P91MNNSN, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C. and Cross, V.A., 2017, Station information, seabed and sample imagery, and CTD instrument data collected on Stellwagen Bank in September, 2016, U.S. Geological Survey Field Activity 2016-038-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P91MNNSN .
    Type_of_Source_Media: digital file (point shapefile, polyline shapefile)
    Source_Contribution:
    This dataset contains the location of the video transects from field activity 2016-038-FA (those that fall within quadrangle 5) that were used in the interpretation. One station from this field activity (4554) was used to define Area W.
    2019-008-FA data (source 11 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in July and August, 2019, U.S. Geological Survey Field Activity 2019-008-FA: data release DOI:10.5066/P93ATKSC, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2020, Sea-floor sediment samples, seabed imagery, and CTD instrument data collected on Stellwagen Bank in July and August, 2019, U.S. Geological Survey Field Activity 2019-008-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P93ATKSC .
    Type_of_Source_Media: digital file (point shapefile, vector data)
    Source_Contribution:
    This dataset contains the location of the video transects from field activity 2019-008-FA (those that fall within quadrangle 5) that were used in the interpretation, as well as the sediment samples. One station from this field activity (4929) was used to define Area W.
    2013-2019 sediment samples (source 12 of 12)
    Valentine, Page C., and Cross, VeeAnn A., 2019, Location and analyses of sediment samples collected on Stellwagen Bank off Boston, Massachusetts from November 5, 2013 to April 30, 2019 during U.S. Geological Survey field activities: data release DOI:10.5066/P9FWFLPD, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Valentine, P.C., and Cross, V.A., 2019, Location and analyses of sediment samples collected on Stellwagen Bank off Boston, Massachusetts from November 5, 2013 to April 30, 2019 on U.S. Geological Survey field activities: U.S. Geological Survey data release, https://doi.org/10.5066/P9FWFLPD .
    Type_of_Source_Media: digital file (polyline shapefile)
    Source_Contribution:
    This dataset contains the location and analyses of sediment samples collected on field activities from 2103 to 2019. The samples that fall within quadrangle 5 were used in the interpretation.
  2. How were the data generated, processed, and modified?
    Date: 2022 (process 1 of 6)
    Methodology description of the interpretation with more details available from Valentine, 2019 (available from the cross-references).
    A geologic substrate is a surface or volume of sediment or rock where physical, chemical, and biological processes occur, such as the movement and deposition of sediment, the formation of bedforms, and the attachment, burrowing, feeding, reproduction, and sheltering of organisms. Data sources used to characterize substrates are multibeam sonar bathymetric and backscatter imagery to document seabed topography and patterns of sediment and rock distribution, grain-size analyses of sediment samples to determine substrate composition, and video and photographic imagery of the seabed to aid in the interpretation of multibeam sonar imagery and to provide information on substrate layering and mobility, seabed structures, and sediments and non-sediment materials that cannot be physically sampled. Substrates are characterized and identified by sediment grain-size composition; the distribution, in millimeters, of grain diameters in the sediment; the presence of non-sediments (for example, rock outcrops); substrate mobility based on the presence of sediment ripples; substrate layering (for example, a partial veneer of sand on gravel); and seabed structures. This methodology was applied to the interpretation of the seabed in this data release. The interpretation itself was an iterative process that took place over a number of years, 2015-2022, primarily 2015-2019. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
    Date: 2022 (process 2 of 6)
    Manual process: Interpretations were drawn on paper maps, which displayed the sun-illuminated topography on which were shown the locations of stations where sediment grain size analysis and video/photo stations were available. These paper maps were printed at a scale of 1:25000 on a large format plotter. The interpretation was based on seabed samples to determine sediment grain size distribution, photo and video imagery to identify small seabed features, multibeam sonar data to identify large seabed features and relative reflectivity (hardness and softness) of seabed sediments. The paper interpretations were transferred to ArcGIS visually based on background data layers in the GIS (ArcMap 9.3.1 for initial work, ArcMap 10.6.1 for final iterations). The process was an iterative one, with the interpretation then printed on the paper maps with underlying bathymetry or backscatter, and interpretation lines adjusted based on the other data printed on the maps.
    
    
    The following information was used as guidelines to derive individual units.
    
    
    Individual sediment samples were aggregated into substrate types by comparing their textural composition, with special emphasis placed on:
    (1) mud, sand, and gravel weight percents;
    (2) sand fraction subdivided into a fine-grained sand composite, fgS (3 and 4 phi), and a coarse-grained sand composite, cgS (0, 1, and 2 phi), in weight percents;
    (3) fine-grained sand fraction subdivided into 3 phi sand and 4 phi sand, in weight percents;
    (4) weight percent of phi (φ) grain sizes;
    (5) significant phi grain sizes (≥10 weight percent of the sample);
    (6) gravel fraction (granules and pebbles only) subdivided into G1 (–1, and –2 phi), and G2 (–3, –4, and –5 phi), in weight percents;
    
    
    Gravel pebbles larger than -5 phi (6.4 cm) were not collected in this study, although larger pebbles, cobbles, and boulders were observed in seabed imagery.
    
    
    Mobility of sediments was determined by the presence or absence of sand ripples, as viewed in video and photographic imagery.
    
    
    Substrate layering was determined by the presence of a layer of finer sediment overlying (but not completely covering) coarser sediment, as viewed in video and photographic imagery.
    
    
    This process was an iterative process that took place over a number of years, 2015-2022, primarily 2015-2019. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Page C. Valentine
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
    Data sources used in this process:
    • DS469
    • SIM2840
    • video
    • 2013-044-FA video lines
    • 2014-015-FA video lines
    • 2014-055-FA video lines
    • 2014-066-FA video lines
    • 2015-017-FA video lines
    • 2015-062-FA data
    • 2019-008-FA data
    • 2013-2019 sediment samples
    Date: 2015 (process 3 of 6)
    Concurrent with the first process step - a file geodatabase was created in ArcCatalog 9.3.1. Within this file geodatabase, a feature dataset was created to contain the datasets associated with the interpretation. The feature dataset was defined with a custom Mercator projection using the following parameters: central longitude -70 degrees 19 minutes; latitude of true scale 41 degrees 39 minutes; false easting and false northing, both 0; datum, NAD 83; linear unit meter. The interpretation of the seabed in the quadrangle extended beyond the quadrangle bounds to help alleviate "boundary faults" when the interpretation is completed in adjacent quadrangles. This is an iterative process taking place from 2015-2022 in conjunction with the work done on the paper maps by Page C. Valentine. The process date represents the initial start of the work and geodatabase creation. This process step and the subsequent steps using were performed by the same person - VeeAnn A. Cross. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 2022 (process 4 of 6)
    In ArcCatalog 10.3.1 a new file geodatabase was created to utilize newer software functionality (modify the field length of a text field). The feature dataset from the ArcGIS 9.3.1 file geodatabase was imported to the new file geodatabase. Topology was created to eliminate overlaps, gaps and slivers. Once the interpretation was completed, the polygon feature class was clipped to the quadrangle boundary published in Valentine and others, 2007. This file geodatabase was subsequently updated with current versions of ArcGIS up to version 10.8.1. These process took place from 2016 to 2022.
    Date: 2022 (process 5 of 6)
    The final modifications to the polygons and clean-up of the polygons and attribute table were performed using ArcMap 10.8.1. This included using XTools Pro 21.1 to calculate the area of each polygon in square kilometers using Table Operations, Calculate Geometry. The spatial reference for the calculation was based on the custom Mercator projection of the file geodatabase.
    Date: 2022 (process 6 of 6)
    The polygon feature class interpretation was exported from the file geodatabase (ArcGIS 10.8.1) to a shapefile using the data frame projection of Geographic, NAD83. Layer files to represent symbolgy were also created to represent the four representations of the seabed to correspond with the maps in the related report (Valentine and Cross, 2024). These layer files are for the geologic substrate (q5_geologic_interp.lyr), sediment mobility (q5_geologic_sediment_mobility.lyr), substrate coarseness (q5_geologic_substrate_coarseness.lyr), and substrate mud content (q5_geologic_substrate_mud_content.lyr).
  3. What similar or related data should the user be aware of?
    Valentine, Page C., and Gallea, Leslie B., 2015, Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 6 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: Scientific Investigations Map 3341, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication contains the equivalent information as this data release, but for quadrangle 6.
    Valentine, Page C., 2019, Sediment classification and the characterization, identification, and mapping of geologic substrates for the glaciated Gulf of Maine seabed and other terrains, providing a physical framework for ecological research and seabed management: Scientific Investigations Report 2019-5073, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This document describes the methodology developed to map the glaciated terrain characterized by geologic substrates that typify a wide range of erosional and depositional sediment environments. This methodology is what was used in this dataset.
    Valentine, Page C., and Cross, VeeAnn A., 2024, Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 5 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: Scientific Investigations Map 3515, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This report is the companion publication of the data release that provides the additional details and information related to the interpretation and methods. Additionally, the report contains PDF map representations of the seabed interpretation. The report also provides additional references related to the work in Stellwagen Bank National Marine Sanctuary.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Navigation for all data upon which the interpretation was based used either differential GPS or GPS. These systems are assumed to have an accuracy better than 10 meters. Some of the data used in the interpretation relied on a towed system. Drift of the towed system was not accounted for. Additional inaccuracies are associated with how the interpretation was drawn in a freehand method. Based on this information, the interpretation is assumed to be accurate to within approximately 40 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This interpretation reflects complete coverage of the study area, quadrangle 5 of the SBNMS region. The data used in compiling maps and the interpretation were collected on scientific cruises conducted by the USGS and sometimes collaborators from NOAA’s Stellwagen Bank National Marine Sanctuary from 1993 to 2019. Many of the project sites were sampled repetitively over this time period and not all data collected was required to compile the maps. The last cruise that provided sediment texture and video data was conducted in November, 2015 (2015-062-FA). Two stations visited at a later date provided data for mapping substrate W. They are: station 4554 (2016-038-FA, September, 2016); and station 4929 (2019-008-FA, July, 2019).
  5. How consistent are the relationships among the observations, including topology?
    The interpretation was carried out by a single person and is consistent throughout the study area, quadrangle 5 of the SBNMS region. There should not be slivers between interpreted polygons, nor should the polygons have overlap. The units are represented by alpha characters. A missing alpha character in the sequence indicates that a unit interpreted elsewhere is not present in this quadrangle. In comparison of other quadrangles that have been interpreted, the primary description of a unit is consistent, but the details of the unit might vary due to specifics in an individual quadrangle. For example, substrate A1 will be a rippled, coarse-grained sand in 2 different quads, but the percentages of mud, sand, or other components can differ slightly in each quad due to some variation in the samples’ mean grain-size distribution.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None.
Use_Constraints The interpretation was completed at a map scale of 1:25,000 and may not be appropriate for use at other scales.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains q5_geol_interp.shp and the shapefile components, the browse graphic (q5_substrate_interp_browse.png), and FGDC CSDGM metadata in XML format. Additionally, the following ArcGIS 10.8.1 layer files are included: q5_geol_interp.lyr, q5_geologic_sediment_mobility.lyr, q5_geologic_substrate_coarseness.lyr, and q5_geologic_substrate_mud_content.lyr. For the LYR files to work correctly, they need to be in the same folder as the shapefile. Downloading the contents of the ScienceBase landing page does not necessarily keep the LYR files in the same folder with the shapefile.
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 20-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: VeeAnn A. Cross
Marine Geologist
384 Woods Hole Road
Woods Hole, MA

508-548-8700 x2251 (voice)
508-457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with the USGS.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9W9BN3S/q5_geologic_interp_meta.faq.html>
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