The Cromwell Gorge is a steep gorge cut by the former Clutha River (Māori: Mata-Au) in the Central Otago region of New Zealand's South Island. It winds between the Dunstan and Cairnmuir Mountains, linking the townships of Cromwell and Clyde. It is one of three substantial river gorges in Central Otago, the others being the Kawarau Gorge to the west of Cromwell, and the Roxburgh Gorge south of Alexandra.
Long-associated with gold mining, orchards and the production of stone fruit, the gorge (including part of old Cromwell) was flooded in the early 1990s to form Lake Dunstan behind the hydroelectric Clyde Dam. The former Otago Central Railway which traced the river through the gorge from Clyde was removed, while State Highway 8 was realigned above the newly formed lake.
The Dunstan Trail, a major new cycle route, was opened on the lake's right bank in 2021.
Geography
The Cromwell Gorge formed in response to the uplift of the Dunstan and Cairnmuir Mountains and simultaneous antecedent incision by the Clutha River. At the northern (upstream) entrance to the gorge lies the township of Cromwell, while the township of Clyde lies to the south. To the east, the gorge is bound by the Dunstan Mountains and to the west, the Cairnmuir Mountains. The overall relief from the highest point of the gorge (Leaning Rock, 1647 m) and the floor of the gorge (Lake Dunstan, 194 m) is .
The Cromwell Gorge is the entrance to the Upper Clutha Valley and was historically an important thoroughfare for early Māori moa hunters, and later pastoralists and gold miners in the late nineteenth century. It remains an important access route into Central Otago's interior via State Highway 8 (SH8).
Geology
The Cromwell Gorge is dominated by the characteristic rocky tors and craggy outcrops of the Haast Schist Group; grey quartzofeldspathic metagreywacke interlayered with micaceous meta-argillite and greenschist formed during the Rangitata Orogeny. The schist in Central Otago has a well-defined pervasive schistosity, with shallow dips defining the broad regional-scale warps in schistosity caused during Miocene deformation (the Kaikoura orogeny). The warped geometries are antiformal over mountain ranges and synformal under the intervening basins. Associated reverse faulting (the Otago fault system) along the south-eastern flanks of many Central Otago mountain ranges (i.e. Taieri Ridge, Lammermoor Range, Rock and Pillar Range, Rough Ridge, Raggedy Range, Dunstan Mountains, Pisa Range) gives rise to the basin and range topography of parallel ridges and basins with steep south-eastern limbs and gently-dipping north-western flanks.
The Cromwell Gorge exits the Dunstan and Cairnmuir Mountains immediately to the north of Clyde. Both mountain ranges are controlled to the south-east by large reverse faults; the Dunstan Fault and Earnscleugh Fault, respectively. Investigations have found that geologically-recent deformation associated with the Dunstan Fault has extended south-west towards Clyde, rather than being translated along the southern margin of the Cairnmuir Mountains. The former Clutha River followed several of these faults as it coursed through the Cromwell Gorge. The arrival of humans in Central Otago resulted in particularly extensive changes in vegetation as Māori hunter-gatherers used clearance fires improvidently. Early Māori firing of woody cover from about the thirteenth century have heavily modified the vegetation cover since European settlement. This is further worsened by Central Otago being the driest region in New Zealand. and thyme, all of which flourish. The introduction of thyme to Central Otago is most-often attributed to Jean Desire Feraud, a French goldminer and orchardist who was part of the Otago gold rush.
There is evidence of native plant regeneration (such as kōwhai) in areas where conservation has been put in place, Forests of kōwhai (Sophora microphylla) have recently been postulated to have also been present in the Cromwell Gorge, upon which moa grazed.
History
Māori
The first settlers in the region were the Māori as they travelled through Central Otago en route to the West Coast on pounamu expeditions, as well as in search of seasonal food resources. Although the Lindis Pass was the usual route for early Māori to access their summer camps at Lake Hāwea and Lake Wānaka, there is sufficient evidence the Cromwell Gorge was used as an important thoroughfare. Early Māori archaeological sites are concentrated through the gorge, particularly on the true left of the former Clutha River, and include small moa hunter camps with associated moa bones. Four sites have been identified at Rockfall I and II, Italian Creek, Muttontown Gully and Clyde West. that the numerous overhangs within the craggy rock formations of the Central Otago river gorges may have been favoured moa nesting locations. Such locations abound in the Cromwell Gorge and eggshell fragments found in many shelters confirm their usage. accompanied by two Māori guides: Reko, a Ngāi Tahu chief from Tuturau, and Kaikōura, a man who had run away from the Kaikōura ranges.
Chalmers made his trip into Central Otago's interior when no roads or tracks existed, hoping to retrace the steps that his guide, Reko, had made from the Waitaki some twenty years earlier. Horatio Hartley and Christopher Reilly worked the sides of the Cromwell Gorge for three months until they were forced to take the huge hoard of gold they had secretly amassed to the Chief Gold Receiver in Dunedin in August 1862. Hartley and Reilly's discovery caused great excitement as they deposited some of gold, sparking a gold rush to what would become known as Hartley's Beach. Hartley and Reilly, in divulging the location of their rich finds (approximately one mile downstream of the Clutha River's confluence with the Kawarau River), were rewarded with £2000 from the Otago Provincial Government. On 23 September 1862 the Dunstan goldfield was proclaimed, the selection of this name in preference to Hartley's being largely in deference to Reilly, who was 'jealous of the pre-eminence' accorded Hartley as the discoverer. but like the earlier gold rush, the times of the dredges drew to a close only several years later.
Chinese miners
In 1865, the Otago Provincial Council invited Chinese miners working on the Victorian goldfields in Australia, to rework the Otago goldfields. European miners had departed in their droves for more lucrative goldfields in Marlborough and the West Coast, opening the door for Chinese mining immigrants to come directly from China, particularly Guangdong province. although it was intended to link the Lakes District (Kingston/Queenstown) via the Kawerau Gorge and not the Cromwell Gorge at the time. Reference to a railway, presumably through the Cromwell Gorge, linking to the Taieri Railway was also made in 1877, but nothing would come of this for another thirty years.
The railway finally made it as far as Clyde in 1907, with the station's official opening on 2 April 1907 by the prime minister, William Hall-Jones. The Cromwell Railway and Progress League, having been formed in 1906 to influence the extension of the railway through the gorge to Cromwell, set about lobbying the Government with increasing frequency. However, work on the railway line stopped at Clyde until 1914. The lobby group stressed the high cost of transport between Cromwell and Clyde, the impact on the region's farmers and also pointed to the inadequacies of the road:
"Irrigation first", was the Government's reply, This would not stop the representations, however.
An announcement to restart the railway extension was made in March 1914, and works were established in the following months with new surveys taking place. The railway started in earnest in September and by the end of 1916 some of rail had been laid. The line to Cromwell was not completed until July 1921 significantly overrunning the predicted two to three years it would take. When the dam itself was completed, the line to Clyde had little other traffic and the section from Middlemarch to Clyde was closed on 30 April 1990. This made the Cromwell Gorge unique in the region and subsequently it produced some of New Zealand's best fruit.
The Annan's were one of the first families to establish an orchard at the southern end of the gorge on what would become Fruitgrowers Road. In 1901 William Annan cleared his piece of land, built a cob shelter, and planted his fruit trees. Imported from Australia, the first trees Annan planted were a diverse mix to test what would be most suitable for the challenging Central Otago climate and included citrus, almond, walnut, cherry, apricot, apple, pear, peach, nectarine, quince and grape.
The last orchardist to leave the Cromwell Gorge ahead of inundation by Lake Dunstan, was Kevin Jackson, who had run an orchard in the gorge from 19691989. Only a few trees from what was Jackson's orchard () still remain at the edge the lake. but it was not until the 1940s that it began to be a more serious option for power in Otago. An examination of the Clutha River's potential in 1944 culminated in the selection and construction of the Roxburgh Dam with first power being produced in 1956. The impact on existing activities from any scheme was recognised from the outset: