Marsden square (original) (raw)

Marsden square mapping or Marsden squares is a system that divides a world map with latitude-longitude gridlines (e.g. plate carrée projection, Mercator or other) between 80°N and 70°S latitudes (or 90°N and 80°S: refer chart at Ocean Teacher’s Ocean Geography page) into grid cells of 10° latitude by 10° longitude, each with a geocode, a unique numeric identifier. The method was devised by William Marsden (b. 1754, d. 1836), when first secretary of the British Admiralty, for collecting and combining geographically-based information about the oceans.