2026-09-19T11:27:59Z http://geonetwork.d4science.org:80/geonetwork/srv/en/oaipmh

geo_fea_bridges 2017-02-14T11:27:44Z PAIM

geo_fea_bridges 2017-02-14T11:27:44 Bridge geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The bridge geomorphic feature layer represents the spatial extent of the bridges of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Bridge geomorphic features were first described by Gardner and Armstrong (2011) as blocks of material that partially infill the Mariana Trench in four locations, forming a “bridge”across the trench. In this study we have extended Gardner and Armstrong’s (2011) interpretation and applied it to all troughs and trenches and have identified a number of bridge features that appear to partially infill trenches and troughs in the global ocean. otherRestrictions no limitations North 83.11179, South -69.185715, East 178.037108, West -178.462294. dataset WMS WFS WCS

geo_fea_trenches 2017-02-14T11:27:38Z PAIM

geo_fea_trenches 2017-02-14T11:27:38 Trench geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The trench geomorphic feature layer represents the spatial extent of the trenches of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Trenches are “a long narrow, characteristically very deep and asymmetrical depression of the sea floor, with relatively steep sides” (IHO, 2008). Trenches are generally distinguished from troughs by their “V” shape in cross section (in contrast with flat-bottomed troughs). In this study trenches were mapped by selecting closed bathymetric contours that defined basins contained within the trench feature, and then joining the basin segments together by hand digitizing along more elevated sections. In this way, bridge features were also identified (as coinciding with infilled sections of trenches; see section on “bridges”). otherRestrictions no limitations North 55.526452, South -61.062679, East 180.0, West -180.0. dataset WMS WFS WCS

geo_fea_slope 2017-02-09T17:06:31Z PAIM

geo_fea_slope 2017-02-09T17:06:31 Slope geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The slope geomorphic feature layer represents the spatial extent of the slope areas of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). The slope is “the deepening sea floor out from the shelf edge to the upper limit of the continental rise, or the point where there is a general decrease in steepness” (IHO, 2008). In this study, the foot of slope was digitised manually at a nominal spatial scale of 1:500,000 in ArcGIS based on 100 m contours and 3D viewing. ArcGIS was used to highlight zones of abrupt changes in seabed gradient (contour spacing) which suggests the foot of slope in many areas. In areas where marginal plateaus abut the margin, the foot of slope was allowed to extend offshore to encompass the plateau feature, where a clear seaward dipping gradient was apparent. Otherwise the first significant decrease in gradient encountered in a seaward direction from the shelf break was selected as the foot of slope. Note our foot of slope locations are based only on bathymetric data and our interpretation is not intended to define the foot of slope under Article 76 of the 1982 United Nations Convention on the Law of the Sea, particularly in areas of geomorphologically complex, continent-ocean transition. otherRestrictions no limitations North 84.540813, South -76.516483, East 180.0, West -180.0. dataset WMS WFS WCS

geo_fea_plateaus 2017-02-14T11:27:40Z PAIM

geo_fea_plateaus 2017-02-14T11:27:40 Plateau geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The plateau geomorphic feature layer represents the spatial extent of the plateaus of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Plateaus are “flat or nearly flat elevations of considerable areal extent, dropping off abruptly on one or more sides” (IHO, 2008). Plateaus were digitised by hand based on 100 m contours. In areas where plateaus abut the margin, the foot of slope was allowed to flow offshore to encompass the plateau feature, where a clear seaward dipping gradient was apparent. In other locations marginal plateaus are distinctly separate from the continental slope and form isolated, raised platforms. The geomorphic features map of Agapova et al (1979) and the GEBCO Gazetteer of geographic names of undersea features were used to ensure all named features were included. otherRestrictions no limitations North 89.616751, South -73.328578, East 180.0, West -180.0. dataset WMS WFS WCS

geo_fea_shelf_valleys 2017-02-14T11:27:43Z PAIM

geo_fea_shelf_valleys 2017-02-14T11:27:43 Shelf valley geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The shelf valley geomorphic feature layer represents the spatial extent of the shelf valleys of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Valleys incised more than 10 m into the continental shelf were digitised by hand. To qualify for inclusion in this study, shelf valleys had to be greater than 10 km in length and >10 m in depth overall. Only features that had a definite elongate shape were included as valleys, nominally more than 4 times greater in length than width. Features that intersected the shelf break and extended both onto the shelf and down-slope (where they become submarine canyons) were also included. otherRestrictions no limitations North 83.796089, South -78.60166, East 179.999934, West -180.0. dataset WMS WFS WCS

geo_fea_canyons 2017-02-14T11:27:40Z PAIM

geo_fea_canyons 2017-02-14T11:27:40 Canyon geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The canyon geomorphic feature layer represents the spatial extent of the canyons of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Submarine canyons are defined as “steep-walled, sinuous valleys with V-shaped cross sections, axes sloping outward as continuously as river-cut land canyons and relief comparable to even the largest of land canyons”(Shepard, 1963). “Large”canyons were mapped in this study based on the definition of Harris and Whiteway (2011), which requires canyons to extend over a depth range of at least 1,000 m and to be incised at least 100 m into the slope at some point along their thalweg. Canyon mapping in this study was based on a combination of automated and expert interpretation of the SRTM30PLUS model. otherRestrictions no limitations North 89.66331, South -76.540347, East 180.0, West -179.999984. dataset WMS WFS WCS

geo_fea_abyss 2017-02-09T17:06:26Z PAIM

geo_fea_abyss 2017-02-09T17:06:26 Abyss geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The abyss geomorphic feature layer represents the spatial extent of the abyssal areas of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). The abyss is the area of seafloor located at depths below the foot of the continental slope and above the depth of the hadal zone (defined as deeper than 6,000 m). The abyss feature layer was created by clipping a layer representing the ocean with the shelf, slope and hadal layers. otherRestrictions no limitations North 90.0, South -76.421159, East 180.0, West -180.0. dataset WMS WFS WCS

geo_fea_ridges 2017-02-14T11:27:42Z PAIM

geo_fea_ridges 2017-02-14T11:27:42 Ridge geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The ridge geomorphic feature layer represents the spatial extent of the ridges of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Ridges in this study are confined to “an isolated (or group of) elongated narrow elevation(s) of varying complexity having steep sides, often separating basin features” (IHO 2008). In this study “ridges” were confined to features greater than 1,000 m in relief and do not include the mid-ocean ridges, which was mapped as a separate feature. otherRestrictions no limitations North 89.550058, South -72.400312, East 180.0, West -180.0. dataset WMS WFS WCS

geo_fea_rift_valleys 2017-02-14T11:27:39Z PAIM

geo_fea_rift_valleys 2017-02-14T11:27:39 Rift valley geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The rift valley geomorphic feature layer represents the spatial extent of the rift valleys of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Rift valleys were mapped as separate features in the present study where they are clearly evident in SRTM30_PLUS bathymetric data. Rift valleys are confined to the central axis of mid-ocean spreading ridges; they are elongate, local depressions flanked generally on both sides by ridges (Macdonald, 2001). They were mapped by hand based on 100 m contours. otherRestrictions no limitations North 87.067827, South -67.844881, East 177.685141, West -178.939175. dataset WMS WFS WCS

geo_fea_guyots 2017-02-14T11:27:43Z PAIM

geo_fea_guyots 2017-02-14T11:27:43 Guyot geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The guyot geomorphic feature layer represents the spatial extent of the guyots of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Guyots are “an isolated (or group of) seamount (s) having a comparatively smooth flat top. Also called tablemount(s)” (IHO, 2008). In this study the seamount base layer was used to mask the SRTM30_PLUS model. The gradient of the resulting grid was calculated (ArcGIS 10->DEM Surface Tools (Jenness 2012)->Slope, Slope computation method = 4-cell method). The gradient was classified into areas >2 degrees and areas 2) they were flagged as possible guyots. These possible guyots were then visually checked and either classified as a guyot or a seamount. Additionally the remaining seamounts were visually checked to see whether any with flat tops had been missed in the classification process. The geomorphic features map of Agapova et al (1979) was used in addition to the GEBCO Gazetteer of geographic names of undersea features (IHO-IOC, 2012), to ensure all previously mapped features were assessed for inclusion in our map. otherRestrictions no limitations North 57.641469, South -69.01585, East 178.557317, West -179.947213. dataset WMS WFS WCS -oai_dc---j9c9yccyhemb-10