Encyclopedia > Geographic datum

  Article Content

Datum

Redirected from Geographic datum

In geology, geography, cartography, surveying and other disciplines, a datum is a reference surface against which measurements can be made. Datum is also the singular for data.

For instance, sea-level is commonly used as a datum against which height (or depth) of topographic features can be measured. Whilst the use of sea-level as a datum is useful for geologically recent topographic features, it should be remembered that sea-level has not stayed constant throughout geological time (see Vail-curve[?]).

On maps, heights and depths will typically be given in height above datum or depth below datum. Ordnance Survey maps define the Ordnance Survey Datum or OSD which is usually sea-level, but should be checked in the map legend.

External Link



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Bullying

... In Classical Antiquity[?] it did not always have inherently negative implications, it merely designated anyone who assumed power for any period of time without a legitimate ...

 
 
 
This page was created in 87.8 ms