Goyder's Line is a boundary line across South Australia corresponding to a rainfall boundary believed to indicate the edge of the area suitable for agriculture. North of Goyder's Line, the rainfall is not reliable enough, and the land is only suitable for grazing and not cropping. The line traces a distinct change in vegetation. To the south, it is composed mainly of mallee scrub whilst to the north salt-bush. In general Goyder's Line represents the demarcation of a long-term rainfall average of 10 inches (254mm).
With barely 30 years' knowledge of this new country to go on, farmers needed reliable information. In 1865 George Goyder provided it. He discouraged farmers from planting crops north of his line, declaring this land suitable only for light grazing. However farmers were optimistic. 1865 was a year of bumper rains, so many ignored Goyder and headed north, starting farms and planting crops. Just a few years later many had to abandon their farms. Goyder was proven correct and the land was indeed unsuitable for crops. Many farmhouse ruins can still be seen near Goyder's line.
There have been periods of development north of the line, but invariably nature has won out. Entire towns and farms were abandoned when there was a return to longer-term average rainfall. The line has proven remarkably accurate, an amazing feat since it was surveyed in just two months in 1865 by Goyder, then the surveyor-general of South Australia.
Goyder's line starts on the west coast near Ceduna and goes south-east across Eyre Peninsula to strike Spencer Gulf near Arno Bay. It continues from near Moonta north to Crystal Brook and Orroroo then south-east past Peterborough and Burra to the Victorian border near Pinnaroo, crossing the Murray River south of Blanchetown. Much of the land immediately north of the line is covered by saltbush. Agriculture is possible near the Murray River further upstream only because of irrigation using water drawn from the Murray.
It is easy to see Goyder's line when flying over this area. The change in flora is very distinct when one knows what to look for.
Goyder's Line became a National Trust of Australia Heritage Icon in 2003, joining other South Australian icons such as Humphrey B. Bear, brush fencing, Stobie poles and Penfolds Grange Hermitage wine.
- The History Trust of South Australia has a map of Goyder's Line.
- Dust Bowl (semi-arid area of the United States)
- Palliser's Triangle (semi-arid area of Canada)
- Semi-arid climate
- Reader's Digest Illustrated Guide to Australian Places (page 538), ISBN 0-86438-399-1
- D.W. Meinig. On The Margins Of The Good Earth: The South Australian Wheat Frontier, 1869-1884. Rigby, 1970.