The diamond in the desert: the story of the giant Readymix logo on the Nullarbor.

Topographic maps and aeronautic charts of the Nullarbor depict a 3.2km x 1.6km diamond shape 13km northwest of Caiguna, on the Nullarbor Plain, labelled "Readymix", "Readymix sign" or "Aerial landmark". The history of the feature is revealed, and placed in the context of the Eyre Highway, during the sealing of which the diamond was created. A cartobibliography for the diamond is also included.

Dedicated to Allan Hoare (21.11.1936-21.6.1989), who carved the diamond

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Thirteen kilometres north-west of the John Eyre motel, at Caiguna on the Eyre Highway, topographic maps and aeronautical charts depict a mysterious diamond shape, labelled "Readymix sign" or "Aerial landmark". Larger scale topographic maps portray the word 'READYMIX' in capital letters inside the diamond. For twenty years from 1972, Guinness Book of Records listed the word as the world's largest letters. This paper investigates this unique cartographic feature, to determine the history of the diamond: who created it, when and why, using surviving documentary sources and interviews with those involved. A possible controversy over the original purpose of the diamond is analysed and explained, and a cartobibliography of maps and aerial photographs depicting the diamond is included.

EARLY NULLARBOR HISTORY

The vast treeless Nullarbor Plain isolates the inhabited areas of Western Australia from those of South Australia. The plain is generally considered to extend 400km west and 300km east of the Western Australia-South Australia boundary, and up to 250km inland from the Great Australian Bight. McKenzie & Robinson (1987, ix) contains an excellent, if now somewhat dated, bibliography for the Nullarbor.

Formed of limestone, the Nullarbor Plain is fairly porous so that any rainfall drains underground, resulting in no surface watercourses and few distinguishing features (Bolam, 1924, 51). The main vegetation includes saltbush (Atriplex spp.) and bluebush (Kochia/Maireana sedifolia), the former being "of the greatest value as forage, succulent and nutritious food for sheep and cattle in the driest season of the year" (Bolam, 1924, 45), and supporting about one sheep per twelve hectares (Reardon, 1996, 82). In non-drought seasons, these well-spaced subshrubs "almost disappear in a sea of grasses and forbs" (Beard, 1975, 40). The Aboriginal groups Mirning, Kokata and Wirangu lived on the periphery of the plain, which they called by the Mirning name of Gondiri, but only after rain would they venture far into it. The remarkably Aboriginal-sounding name 'Nullarbor', Latin for 'no trees', was given to the plain by South Australian surveyor Edmund Delisser, who explored into it in 1865-66 (Reardon, 1996, 13 & 33; see Delisser, 1867).