The Arahura River, 35 miles in length, rises in the Southern Alps at Browning Pass and flows west, then north, then west again to reach the Westland lowland just north of Lake Kaniere, whence it flows north-west to the sea, 5 miles north of Hokitika. Major tributaries in the mountains are Harman River, Newton Creek, Olderog Creek, and Wainihinihi River and, near the coast, Kaiwaka Creek. In common with the larger Westland rivers it has been glaciated during the Pleistocene age, and moraines and associated glacial landforms extend on to the coastal lowlands. An overflow of the Arahura Glacier extended down the Styx River from the upper valley via Styx Saddle. The lower reaches of the Arahura Valley, particularly from Humphreys Gully to the sea, have been extensively sluiced and later dredged for gold. This area was a major producer in the past, but is now worked out.
This valley appears to have been the major source of greenstone (nephrite) formerly recovered from gravels during gold-working operations, but now confined to the river bed between Milltown and the lower reaches of Olderog Creek. This area contains the only known reserves of greenstone.
During the latter part of the nineteenth century a route up the Styx River and upper Arahura Valley, over Browning Pass (4,750 ft) to Canterbury via the Wilberforce River, was much used by prospectors, and the first sheep in Westland were driven over it. The formed track is still open over much of the route.
Some authorities consider that the name Arahura was given by Ngahue, the companion of Kupe, the navigator. It is said to be properly Ara'ura, which is the ancient name of Aitutaki , a legendary homeland of the Maoris.
by Alan Copland Beck, M.SC., New Zealand Geological Survey, Christchurch.