This extensive area is centred on the hugely important Consolidated, United and Poldice mines near St. Day. The Scorrier mines (including North Downs) and Wheal Busy form its northern and eastern boundary, whilst the district extends via the Carnon Valley and the mines which flank it to the port of Devoran on the Fal Estuary to the south-east. The district was also linked to the north coast at Portreath, from which much of its copper ores were shipped.

Historically, this was the richest mining district in Cornwall during the late 18^th and early 19^th centuries, and was referred to by contemporary writers as the ‘richest square mile to be found anywhere on the earth’. Here, more than anywhere else in Cornwall, the landscape clearly displays the effects of extensive copper mining.

Most of the mines of this district were relatively shallow, none being deeper than 400 metres below adit. They were, however, extraordinarily rich: for example Treskerby produced 32,000 tons of copper ore, North Treskerby (19,000 tons), Hallenbeagle (30,000 tons), Wheal Damsel (37,000 tons), Wheal Gorland (40,000 tons), Wheal Jewel (58,000 tons), Ting Tang (40,000 tons) were also important concerns, but the really massive producers were Poldice (108,000 tons), Great Wheal Busy (100,000 tons of copper ore and 27,000 tons of arsenic), the Consolidated Mines (442,000 tons) and the United Mines (over 350,000 tons).
 

The champion mines of the district were, without a doubt, those immediately to the south of St Day. Copper production here seems to have begun in about 1757 (at Wheal Virgin). By 1779, Wheal Virgin, West Wheal Virgin, Wheal Maid and Carharrack Mine were being worked by seven Newcomen engines and in the following year they were amalgamated into the Consolidated Mines. Outputs of ore from both these and the neighbouring United Mines were substantial, but both closed in 1805 during a low period for Cornish mines. The United Mines were restarted in 1811, the mine extending over a mile and a half of countryside, with the Consolidated Mines being reopened by John Taylor in 1819. From 1824, the two mines were worked as a single concern under his guidance, with Arthur Woolf as his chief engineer. By 1838, there were 21 steam engines on the mine, which employed 3,196 persons. From 1819-1840, nearly 300,000 tons of ore were raised and over 63 miles of development levels and shafts cut. Lemon’s statistics give some indication of the scale of mining here: in 1836, the Consolidated Mines used 11,817 tons coal, 113,916 lbs candles and 64,000 lbs gunpowder. Over a quarter of the population of Gwennap parish (8,539) worked in this one mine.

Huge fortunes were being made by shareholders, promoters and mineral lords like the Willams family of Scorrier or William Lemon, whose agent gained the nickname ‘guinea a minute’ Daniell.

So impressive was the industry of the district that in 1845, William Francis, Vicar of Gwennap, felt impelled to write a poem in seven cantos about the history and wonders of the parish. Written in the style of Virgil (though sadly Francis was no great shakes as a poet), his oeuvre provides much interesting description of the mines and their working and provides an insight into a period when mining was still viewed with unquestioning optimism.

John Taylor was refused the right to renew his sett agreement with the mineral lords and although the mine was reworked (as Clifford Amalgamated), employing over 2000 people, production was falling and outlay exceeding returns. The mine was abandoned in 1870, the machinery dismantled and many of the buildings demolished for their stone. Numerous other mines of the district had closed not long before.

Probably the most dramatic engineering achievement within the district, indeed in Cornwall as a whole during the period was the construction of what was to become the Great County Adit. Begun in 1748 by John Williams of Scorrier to drain Poldice, this extraordinary drainage system was gradually extended to the other mines of the district, by 1778 having been driven through Wheal Busy to North Downs and on into Wheal Peevor, another branch from Poldice had been cut by 1792 into Wheal Unity and Gorland, whilst Consolidated and United Mines also discharged their water into the system, which eventually reached the outskirts of Redruth and extended to a length of 40 miles. Although parts of the system no longer function, many of the mines of the district still discharge through the adit into the Carnon River.
 

For such a rich mining district, it may at first seem odd that it contains no large settlements. Gwennap is little more than a churchtown; St Day has medieval origins and Chacewater was established during the 18^th century; none of which grew to any great size; Lanner, Carharrack and Devoran, based on rows (terraces) or artisans’ cottages are later creations, yet the parish of Gwennap had a population of over 8,500 in the early 1830s. Historical maps of the area provide the answer. A huge proportion of the current agricultural land in the parish is of recent creation and much of it is made of former miners’ smallholdings. The population, it seems, was dispersed across the parish during the earlier 19^th century, and miners were also by and large small-scale farmers as well. The area still retains much of this character – isolated cottages with here and there a group of terraced cottages set in a landscape of small fields. The railway from Chacewater to Truro passes through a landscape where almost every hedge is planted with oaks of the same variety and age – a strong indication of the planned parcellation of open downland by a single landowner. At Poldice and the Consolidated Mines, in contrast, hectares of bare mine dumps are returning back to heathland.