Mid North and Iron Triangle
The term Mid North is the popular name of a region which lacks precise boundary definition. The area extends to include the three cities - Port Augusta, Port Pirie and Whyalla - commonly know as the Iron Triangle.
The Mid North has some of the best agricultural and pastoral land in the State. In the nineteenth century it was the heartland of the colony's productivity, and it bears the marks of a long and generally benign European occupation. The damage caused by former widespread soil erosion has largely been repaired.
Although the terrain is varied, it is rugged only in the South Flinders Ranges. On the west is a coastal plain, narrowing north of Port Pirie. East of the plain a series of ridges of sandstones and quartzite run roughly north and south. Between them, on less resistant shales and slates, are wide valleys and flats. There is an intricate pattern of streams, but most flow only after heavy rain. Annual rainfall varies between 350mm and 500 mm, with falls up to 650 mm in a few areas in the Clare hills and South Flinders Ranges.
Abundant outcrops of easily quarried stone provided early settlers with building materials in a region where suitable timber was scarce. Stone was used to build hundreds of farmhouses, scores of grand homesteads, many small churches, and the solid buildings of the closely spaced country towns. The generous sprinkling of ruined farmhouses is the product not of agricultural failure, except on the far northern and eastern margins of the region, but of steady farm consolidation and enlargement.
The most extensive soils are of duplex type, good for wheat growing because their clay subsoils hold water well. The topsoils suffered water erosion until farmers adopted contour banking and other improved farming practices. In 1981, the region produced about 17% of the value of the State's farm output. About 34% of that was wheat, 18% barley, and 30% from sheep and cattle. There are also vineyards and orchards on the hilly slopes between Auburn and the Hutt River, north of Clare, and early vegetables - especially tomatoes and peas - are grown on the western slopes of the Flinders Ranges between Warnertown and Baroota.
The Mid North has long been famous for its merino sheep studs. Many of them survive on residual portions of great freehold estates which were assembled by the 1860s, and partly repurchased and subdivided by the government under closer settlement schemes after 1900. In the Jamestown and Wirrabara districts there are forest plantations of exotic softwoods and indigenous hardwoods which form the basis of a timber industry serving regional needs.
Agricultural settlement in the southern part of the region spread vigorously in the 1850s on the heels of pastoral expansion in the 1840s and the discovery of copper at Burra in 1845. The hills around Burra were cleared of most of their timber for use in the mines and smelters. The plausible resemblance of the landscape to the South African veldt led the South Australian Film Corporation to use the area as the location for the film Breaker Morant.
North-west of the main agricultural district of the Mid North lie Port Augusta, Port Pirie and Whyalla at the head of Spencer Gulf. These are alternatively called the Iron Triangle or the Gulf Cities. Each depends on one or two basic industries for much of its employment. Despite their proximity, the cities have no close economic linkages, each play separate, specialist roles in the State and national economies. In 1981, the three together had a population of 60,000, 4.7% of the State total.
Port Augusta (population 15,254) was developed in the 1860s at the head of Spencer Gulf. It exported wool from the pastoral north and later copper from the Flinders Ranges and grain from the Quorn-Hawker district. It now serves as an operational and administrative base for the Australian National railway, and as a centre for generating electric power using Leigh Creek coal.
Port Pirie (population 14,695) was surveyed in 1871, although there was a settlement at Solomontown as early as 1848. The town owed its growth to the wheat boom of the 1870s and the development of the Broken Hill mines in the 1880s. A narrow-gauge railway was built from Broken Hill via Silverton, Cockburn and Crystal Brook, and in 1889 three smelters opened at Port Pirie to treat the silver-lead ores. Today Broken Hill Associated Smelters Pty Ltd operates one of the world's largest single-unit lead smelters, producing about 10% of the world output of refined lead. The anticipated run-down of mining operations at Broken Hill about the turn of the twentieth century must cast long-term doubts on Port Pirie's future unless alternative sources of ore are found.
Whyalla is the State's largest provincial city. Its peak population of 33,000 in 1976 had declined to 29,962 in 1981. It depends uniquely on the operations of one company, Broken Hills Pty Co Ltd. High quality iron ore was first mined from Iron Knob in 1900 as a flux for use in the Port Pirie smelters. Productions increased from 1915 when the ore was shipped from Whyalla for steel manufacture at Newcastle and later at Port Kembla. Iron ore was discovered in 1920 at Iron Baron in the Middleback Range and mined from 1933. In 1941, the first blast furnace began operating at Whyalla and the city grew rapidly as a shipbuilding and steel-making centre. With the closure of the shipyards in 1976 and reduced demand for steel, there has lately been declining employment and some outward migration. The steelworks have shed some 2400 jobs from a peak of 6900. Recently, about 70% of Whyalla steel has been sold to Australian users, and most of the rest to China.
Changes in the fortunes of the Iron Triangle cities may depend on future resource developments farther afield, such as the Cooper Basin gasfields, the Roxby Downs copper-gold-uranium ores, and possibly the coal deposits in the Arckaringa Basin at Lake Phillipson south of Coober Pedy.