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  2. Ordnance Survey - Wikipedia

    en.wikipedia.org/wiki/Ordnance_Survey

    The British Geological Survey was founded in 1835 as the Ordnance Geological Survey under Henry De la Beche, and remained a branch of the Ordnance Survey until 1965. At the same time, the uneven quality of the English and Scottish maps was being improved by engravers under Benjamin Baker .

  3. Geologic map - Wikipedia

    en.wikipedia.org/wiki/Geologic_map

    The maps are superimposed over a topographic map base produced by Ordnance Survey (OS), and use symbols to represent fault lines, strike and dip or geological units, boreholes etc. Colors are used to represent different geological units. Explanatory booklets (memoirs) are produced for many sheets at the 1:50,000 scale.

  4. Ordnance datum - Wikipedia

    en.wikipedia.org/wiki/Ordnance_datum

    An ordnance datum (OD) is a vertical datum used by an ordnance survey as the basis for deriving altitudes on maps. A spot height may be expressed as above ordnance datum ( AOD ). Usually mean sea level (MSL) at a particular place is used for the datum.

  5. Benchmark (surveying) - Wikipedia

    en.wikipedia.org/wiki/Benchmark_(surveying)

    An Ordnance Survey cut mark in the UK Occasionally a non-vertical face, and a slightly different mark, was used. The term benchmark, bench mark, or survey benchmark originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle iron could be placed to form a "bench" for a leveling rod, thus ensuring that a leveling rod could be accurately ...

  6. Chart datum - Wikipedia

    en.wikipedia.org/wiki/Chart_datum

    A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [1] Common chart datums are lowest astronomical tide (LAT) [1] and mean lower low water (MLLW).

  7. Vertical datum - Wikipedia

    en.wikipedia.org/wiki/Vertical_datum

    A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [8] Common chart datums are lowest astronomical tide (LAT) [8] and mean lower low water (MLLW).

  8. Ordnance Survey National Grid - Wikipedia

    en.wikipedia.org/wiki/Ordnance_Survey_National_Grid

    The Ordnance Survey National Grid reference system (OSGB), also known as British National Grid (BNG), [1] [2] is a system of geographic grid references, distinct from latitude and longitude, whereby any location in Great Britain can be described in terms of its distance from the origin (0, 0), which lies to the west of the Isles of Scilly.

  9. Ordnance Survey Drawings - Wikipedia

    en.wikipedia.org/wiki/Ordnance_Survey_Drawings

    The Ordnance Survey Drawings are a series of 351 of the original preliminary drawings made by the surveyors of the Ordnance Survey between the 1780s and 1840 in preparation for the publication of the one-inch-to-the-mile "Old Series" of maps of England and Wales.