2026-08-04T23:04:38Z http://geonetwork.d4science.org:80/geonetwork/srv/en/oaipmh

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_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_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_seamounts 2017-02-14T11:27:39Z PAIM

geo_fea_seamounts 2017-02-14T11:27:39 Seamount geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The seamount geomorphic feature layer represents the spatial extent of the seamounts 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). Seamounts are “a discrete (or group of) large isolated elevation(s), greater than 1,000 m in relief above the sea floor, characteristically of conical form” (IHO, 2008). Seamounts are thus defined as peaks that rise over 1,000 m above the seafloor, calculated based on the SRTM30_PLUS model. We adhered strictly to the requirement that seamounts are “of conical form”, thus distinguishing “seamounts” (having a length/with ratio th ratio ≥2). The criterion of a length/with ratio . otherRestrictions no limitations North 77.084697, South -75.23333, East 180.0, West -180.0. dataset WMS WFS WCS

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

geo_fea_fans 2017-02-14T11:27:44 Fan geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The fan geomorphic feature layer represents the spatial extent of the fans 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). Fans are “a relatively smooth, fan-like, depositional feature normally sloping away from the outer termination of a canyon or canyon system” (IHO, 2008). Since submarine fans are sediment deposits, the NGDC map of global ocean sediment thickness (Divins, 2003) was used to assist with identifying them. Fans overlay and comprise part of the continental rise and are located offshore from the base of the continental slope (Curray et al., 2002; Dowdeswell et al., 2008; Covault et al., 2011). Fans are inter-related with submarine canyons and sediment drift deposits; in cases where canyon axes extend across the rise, the canyon-channels may be flanked by sediment drift deposits, which have been grouped with fans in this study. Fans are defined in the present study by 100 m isobaths that form a concentric series exhibiting an expanding spacing in a seaward direction away from the base of the slope, sometimes clearly associated with a canyon mouth, but also comprising low-relief ridges between canyon-channels on the abyssal plain. otherRestrictions no limitations North 84.569183, South -76.421159, East 179.96163, West -176.524275. dataset WMS WFS WCS

geo_fea_rises 2017-02-14T11:27:41Z PAIM

geo_fea_rises 2017-02-14T11:27:41 Rise geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The rise geomorphic feature layer represents the spatial extent of the rises 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 continental rise was digitised by hand at a nominal spatial scale of 1:3,000,000 in ArcGIS based on 100 m contours. A map of global ocean sediment thickness (Divins, 2003) was used to assist with identifying potential rise areas. In general the rise was confined to areas of sediment thickness >300 m. Criteria for identification of continental rises included the occurrence of a smooth sloping seabed as indicated by evenly-spaced, slope-parallel contours (Curray et al., 2002; Dowdeswell et al., 2008; Covault et al., 2011). In this study, the term “Rise” was restricted to features that abut continental margins and does not include the mid-ocean ridge (or “rise”), which was mapped as a separate feature. The GEBCO Gazetteer of geographic names of undersea features (IHO-IOC, 2012) was used to ensure all named features were included. otherRestrictions no limitations North 84.537464, South -76.421159, 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_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

geo_fea_glacial_troughs 2017-02-14T11:27:41Z PAIM

geo_fea_glacial_troughs 2017-02-14T11:27:41 Glacial trough geomorphic feature layer Geology global seafloor, geomorphic features, habitats Downloadable Data The glacial trough geomorphic feature layer represents the spatial extent of the glacial troughs 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). Shelf valleys at high latitudes incised by glacial erosion during the Pleistocene ice ages form elongate troughs, typically trending across the continental shelf and extending inland as fjord complexes (Hambrey, 1994). The largest of these features are glacial troughs, characterised by depths of over 100 m (often exceeding 1,000 m depth) and are distinguished from shelf valleys by an over-deepened longitudinal profile that reaches a maximum depth inboard of the shelf break, thus creating a perched basin on the shelf with an associated sill (Hambrey, 1994). Glacial troughs were digitized by hand based on 50 m contoured data for the Antarctic and 10 m contoured data for other shelf areas. otherRestrictions no limitations North 83.796089, South -78.60166, East 180.0, West -180.0. dataset WMS WFS WCS -oai_dc---1ecga3qkv8gzz-10