Ōpārara Arch
Interesting facts
- Bones from the nearby Honeycomb Hill caves include the first and most complete remains of Haast's eagle, now displayed at Te Papa museum in Wellington.
- Some intact bird skeletons recovered from the basin's limestone caves are more than 20,000 years old, preserved by steady cave temperatures and the chemistry of the rock.
- The Honeycomb Hill cave system has about 70 entrances and roughly 13 km of passages, inventoried by the Buller Caving Group in the 1980s.
- An old sign at the end of the track gave the arch as 200 m long, 49 m wide and 37 m high, well short of later official measurements.
- Just downstream of the main tunnel stands a shorter but even taller rock arch, about 10 m long and roughly 10 m away from it.
- The rare moss Epipterygium opararense is named after the basin and grows near its cave and arch entrances; only about 175 plants have ever been found.
- The basin is the only known home of the carnivorous land snail Powelliphanta marchanti, so strictly protected that even collecting its empty shells is banned.
- Natural rock arches in the Ōpārara valley were already marked on maps in the 1880s.
- Besides Moria Gate, Lord of the Rings names in the valley include Galadriel Creek and Nimrodel Creek.
- Part of the path near Moria Gate Arch is paved with stones imprinted with the footprints of moa, the extinct giant birds found in the local caves.
Why it is worth it
The Ōpārara River runs straight through a hill of limestone in the rainforest of the northwest South Island of New Zealand, and the tunnel it has carved is big enough to hold a multi-storey building. Ōpārara Arch is the largest natural rock arch in the Southern Hemisphere: by the Department of Conservation's measurements it is about 219 metres long, up to 79 metres wide and 43 metres high. Inside, the river slides beneath the vault stained the colour of strong tea by tannins leached from the surrounding forest, and after rain a small waterfall can spill from the middle of the roof.
The arch lies in the Ōpārara Basin on the edge of Kahurangi National Park. Here a granite basement some 350 million years old is overlain by a relatively thin layer of limestone deposited around 35 million years ago. Rainfall of up to six metres a year, together with the roots of the dense beech and podocarp forest, has dissolved and broken that limestone into a karst landscape of caves, gorges and arches. The walking track follows the river upstream to a viewpoint high inside the arch, from which both entrances and the river below are visible, and where stalactites and stalagmites are beginning to form. Nearby, the smaller Moria Gate Arch — named, like several places in the valley, after The Lord of the Rings — opens over the same river, 19 metres high and 43 metres wide, its ceiling hung with stalactites and roots.
The basin is also a site of global importance for fossils. The cave system of Honeycomb Hill, explored in the 1980s, has yielded the largest collection of bird fossils found in New Zealand, including the most complete remains of the extinct Haast's eagle and nine species of moa. Today the forest is home to great spotted kiwi, blue duck and kea, and to giant carnivorous land snails found nowhere else.
Getting there
The arch is about 20 km north of Karamea on the West Coast of the South Island. A forestry road of about 12 km leaves the main road some 9 km north of Karamea and ends at a car park by the river, from which walking tracks lead to the arches. The nearest airport is Westport Airport (WSZ), about 83 km away in a straight line.
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From the encyclopaedia
The Ōpārara Basin Arches are a number of natural limestone tunnels formed by the Ōpārara River, in the Ōpārara Basin, New Zealand. The two most famous ones are the 'Ōpārara Arch', large enough for a multi-storey house, and the 'Moria Gate Arch', which is smaller in height.
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