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Bathymeric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
Depth contour lines show the shape of underwater relief. Coloured areas of the sea emphasise shallow water and dangerous underwater obstructions. Depths are measured from the chart datum, which is related to the local sea level. The chart datum varies according to the standard used by each national Hydrographic Office.
Edmond Halley's New and Correct Chart Shewing the Variations of the Compass (1701). The idea of lines that join points of equal value was rediscovered several times. The oldest known isobath (contour line of constant depth) is found on a map dated 1584 of the river Spaarne, near Haarlem, by Dutchman Pieter Bruinsz. [7]
Topographic maps display elevation above ground and are complementary to bathymetric charts. Bathymeric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount ...
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the years it has become a reference map of the bathymetry of the world's oceans for scientists and others.
If the plummet came up clean, it meant the bottom was rock. Nautical charts provide information about the seabed materials at particular locations. [3] Nautical charts also include depth contour lines. It is thus sometimes possible to navigate in poor visibility by noting which contour line one is closest to.
Section of topographical map of Nablus area with contour lines at 100-meter intervals. Heights are colour-coded. Heights are colour-coded. In modern mapping, a topographic map or topographic sheet is a type of map characterized by large- scale detail and quantitative representation of relief features, usually using contour lines (connecting ...
Admiralty charts include information on: depths (chart datum), coastline, buoyage, land and underwater contour lines, seabed composition, hazards, tidal information (indicated by "tidal diamonds"), prominent land features, traffic separation schemes radio direction finding (RDF) information, lights, and other information to assist in navigation ...