Denniston Plateau (technically the Denniston-Stockton Plateau) is an 18 km long, 600–800 m high

coalfield A coalfield is an area of certain uniform characteristics where coal is mined. The criteria for determining the approximate boundary of a coalfield are geographical and cultural, in addition to geological. A coalfield often groups the seams of ...

plateau in the

Papahaua Range The Papahaua Range is a mountain range on the West Coast of New Zealand's South Island east of the town of Westport. It is a geological continuation of the Paparoa Range that is south of the Buller River and it runs north from the Buller Gorge ...

on the West Coast of the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

of New Zealand. A combination of impermeable rock, high rainfall, and shallow acidic soil has created a unique ecosystem of stunted trees and

heath A heath () is a shrubland habitat found mainly on free-draining infertile, acidic soils and is characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great Britain—a coole ...

-like vegetation which is home to numerous

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

and undescribed species of plants and invertebrates. The plateau contains rich seams of high-quality coal, which led to the creation and abandonment of the mining towns of Denniston and Millerton, and the current

Stockton Mine Stockton Mine, on the Stockton Coal Field, is New Zealand's largest opencast mining operation. The entrance to the mine is at the former settlement of Stockton. Extent The coal field is situated between 5 and 10 kilometres linear distance ...

. Plans to create a new open-cast mine on the southern part of the plateau have become an environmental controversy.

Physiography

The Denniston-Stockton Plateau stretches approximately , from Mt Rochfort near Westport in the south to Granity in the north. It is about wide, and above sea level, lower at its northern ( Millerton) and southern ( Denniston) extents, and highest in the middle towards Mount Frederick. It is bisected by the

Waimangaroa River The Waimangaroa River is located on the West Coast of New Zealand. The river passes through tussock, scrub and forested areas before draining into the Karamea Bight in the Tasman Sea. It passes through the town of Waimangaroa and is crossed ...

into Denniston and Stockton plateaus, which are sometimes referred to individually, though the term "Denniston Plateau" is often used to refer to the entire landform and ecosystem.

Geology

The main rock on the surface of the plateau is

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

, which has eroded into coarse and acidic

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

sand. It is sometimes referred to as the "Buller Coal Plateau", because beneath the sandstone are rich seams of high-quality

bituminous coal Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the coal seam, ...

, laid down in swamps 45 million years ago. Partly-decayed plant material was compressed into

peat Peat is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...

42–45 million years ago, then covered over by encroaching ocean and rock, and compressed once again under the ocean into coal 37 million years ago. The plateau was raised to its current altitude within the last 2 million years as part of the rapidly-rising

Southern Alps The Southern Alps (; officially Southern Alps / Kā Tiritiri o te Moana) are a mountain range extending along much of the length of New Zealand, New Zealand's South Island, reaching its greatest elevations near the range's western side. The n ...

The soil on the plateau is thin at best, often infertile and low in organic matter, poorly drained, and acidic; miners in Denniston had to bring all the soil required to create their flower gardens and bowling green up the Denniston Incline. Yet, it supports a diverse ecology. The impermeable layer of sandstone means the ground is frequently waterlogged and there are large expanses of bare, eroded rock with no soil at all. Unique ecologies, or

sky island Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau and has extended to similarly isolated high-elevation forests. The isolation has s ...

s, develop on isolated mountain tops and on the Denniston Plateau, the expanses of frequently waterlogged ground have also contributed to speciation by keeping plants and animals highly isolated. Consequently, the Plateau supports an ecological system that is uniquely associated with the local geology.

Climate

The plateau has a harsh climate: high rainfall, low sunshine hours, cold, wind, and often mist.

Flora

The vegetation of the plateau appears sparse and scrubby, but this is an adaptation to the harsh climate and poor soils: there is a high diversity of plant species, many of which take a miniature form relative to their better-known cousins, and some of the

bonsai Bonsai (; , ) is the Japanese art of Horticulture, growing and shaping miniature trees in containers, with a long documented history of influences and native Japanese development over a thousand years, and with unique aesthetics, cultural hist ...

-like small shrubs are hundreds of years old. The plateau includes alpine plants found at unusually low altitudes and several localised or endemic plants. Denniston Plateau MRD 07

In more sheltered areas and better soils, the vegetation is a low forest consisting of

mānuka Mānuka (; ''Leptospermum scoparium'') is a species of flowering plant in the myrtle family (biology), family Myrtaceae, native to New Zealand (including the Chatham Islands) and south-east Australia. Bees produce mānuka honey from its necta ...

(''Leptospermum scopiarium''), mountain five-finger (''Neopanax colensoi''),

southern rātā ''Metrosideros umbellata'', the southern rātā, is a tree endemic to New Zealand. It grows up to or more tall with a trunk up to or more in diameter. It produces masses of red flowers in summer. Unlike its relative, northern rātā, this spe ...

(''Metrosideros umbellata''), and

mountain flax ''Phormium colensoi'' (syn. ''Phormium cookianum'' – see below), also called mountain flax, or in Māori, is a perennial plant that is endemic to New Zealand. The greenish, yellow or orange flowers are followed by twisted seed pods. It is le ...

(''Phormium colensoi''). In more exposed areas the growing conditions are similar to the

pakihi Pakihi or pākihi is a vegetation association unique to the West Coast of the South Island of New Zealand, characterised by flat boggy land with infertile, waterlogged soil on which only rushes, ferns, moss, and mānuka grow. Name The Māo ...

swampland of lower altitudes, and contains similar species such as mānuka, tangle fern (''Gleischenia dicarpa''), and various rushes. But the more varied topography of the plateau creates greater diversity of habitats and species, including bog pine (''Halocarpus bidwillii''), pygmy pine (''Lepidothamnus laxifolius''), yellow silver pine (''L. intermedius''), and several species of shrubby or stunted ''

Dracophyllum ''Dracophyllum'' is a genus of plants belonging to the family Ericaceae, formerly Epacridaceae. There are 61 species in the genus, mostly shrubs, but also cushion plants and trees, found in New Zealand, Australia, Lord Howe Island and New Caledon ...

''. North towards Millerton the rocky plateau has dwarfed

kāmahi ''Pterophylla racemosa'', commonly known as the kāmahi, is an evergreen tree endemic to New Zealand. It is a member of the Cunoniaceae family of plants, and it is often referred to by its former botanical name ''Weinmannia racemosa.'' Most me ...

(''Weinmannia racemosa''), and both southern and

northern rātā Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a ra ...

(''Metrosideros robusta''). Many small flowers occur on the plateau: gentians, eyebright ('' Euphrasia wettsteiniana''), orchids such as the mauve sun orchid (''Thelymitra decora'') and swamp sun orchid (''T. cyanea''), and in wetter areas carnivorous sundews ('' Drosera spatulata''). Some distinctive species include: * ''

Dracophyllum townsonii ''Dracophyllum townsonii'' is a species of shrub or small tree endemic to the north of New Zealand's South Island. It was first described by Thomas Cheeseman in 1906 and gets the specific epithet ''townsonii'' after the chemist and plant collect ...

,'' restricted to the northern West Coast, and '' D. densum'', found mostly on Denniston Plateau and the

Paparoa Range The Paparoa Range is a mountain range in the West Coast region of New Zealand's South Island. It was the first New Zealand land seen by a European – Abel Tasman in 1642. Part of the range has the country's highest protection as a national par ...

nearby * Four species of ''

Celmisia ''Celmisia'' (New Zealand aster or New Zealand daisy) is a genus of perennial herbs or subshrubs, in the family Asteraceae. Most of the species are endemic to New Zealand; several others are endemic to Australia. ; Species and nothospecies #RED ...

'' daisies that reach their southern limit here or in the Paparoas: mountain daisy (''C. dubia''), scrub daisy (''C. lateralis''), Dall's mountain daisy (''C. dalii''), and ''C. similus.'' * North Westland snow tussock (''

Chionochloa juncea ''Chionochloa'' is a genus of tussock grass in the family Poaceae, found primarily in New Zealand with one known species in New Guinea and another on Lord Howe Island (part of Australia). Some of the species are referred to as snowgrass or snow ...

''), found only on the Denniston-Stockton Plateau

Fauna

The plateau has

great spotted kiwi The great spotted kiwi, great grey kiwiDavies, S. J. J. F. (2003) or roroa (''Apteryx maxima'') is a species of kiwi endemic to the South Island of New Zealand. The great spotted kiwi, as a member of the ratites, is flightless. It is the large ...

(''Apteryx haastii''), fernbirds (''Poodytes punctatus'') and New Zealand pipits (''Anthus novaeseelandiae''), as well as

weka The weka, also known as the Māori hen or woodhen (''Gallirallus australis'') is a flightless bird species of the rail family. It is endemic to New Zealand. Some authorities consider it as the only extant member of the genus '' Gallirallus''. ...

kea The kea ( ; ; ''Nestor notabilis'') is a species of large parrot in the Family (biology), family Strigopidae that is endemic to the forested and alpine regions of the South Island of New Zealand. About long, it is mostly olive-green, with br ...

, and

riflemen A rifleman is an infantry soldier armed with a rifled long gun. Although the rifleman role had its origin with 16th century hand cannoneers and 17th century musketeers, the term originated in the 18th century with the introduction of the r ...

. Reptiles include speckled skink, coastal green gecko, and forest gecko (which here inhabits scrubland). Several species of large carnivorous ''

Powelliphanta ''Powelliphanta'' is a genus of large, air-breathing land snails, pulmonate gastropods in the family Rhytididae, found only in New Zealand. They are carnivorous, eating invertebrates, mostly native earthworms. Often restricted to very small area ...

'' snail are found on the plateau, and some are endemic to it and threatened by mining. * '' Powelliphanta patrickensis'', found only on coalfields over 750 m between Denniston and Mt Rochfort and in the Millerton area * '' Powelliphanta lignaria'' 'Millerton', found only on a few hectares near Millerton, thought to be extinct, and rediscovered in 2005 * ''

Powelliphanta augusta ''Powelliphanta augusta'' or the Mount Augustus snail, previously provisionally known as ''Powelliphanta'' "Augustus", is a species of large, carnivorous land snail, a terrestrial pulmonate gastropod mollusc in the family Rhytididae. Naturally ...

'', whose 5 ha of habitat on Mount Augustus was destroyed by the mining company

Solid Energy Solid Energy was the largest coal mining company in New Zealand and is a state owned enterprise of the New Zealand Government. The company was formed from the former government department State Coal Mines. It was then established as a state ow ...

. Four thousand snails were relocated, and 2,000 taken into captivity in refrigerated shipping containers in 2006. Attempts to reintroduce the captive snails in the Stockton area were unsuccessful, and nearly 2,000 remain in plastic containers in cold storage, cared for by the

Department of Conservation Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

until they are confident the species can survive in the wild. A refrigeration accident in 2011 killed 800 of the snails. In response to a proposed open-cast coal mine, 150 scientists and volunteers conducted a weekend

bioblitz A BioBlitz, also written without capitals as bioblitz, is an intense period of biological surveying in an attempt to record all the living species within a designated area. Groups of scientists, naturalists, and volunteers conduct an intensive ...

on the plateau in March 2012 and discovered several new species: * a nationally critically endangered day-flying moth, '' Arctesthes avatar'', described in 2019 and named after the movie ''

Avatar Avatar (, ; ) is a concept within Hinduism that in Sanskrit literally means . It signifies the material appearance or incarnation of a powerful deity, or spirit on Earth. The relative verb to "alight, to make one's appearance" is sometimes u ...

'', whose plot concerns a mining company destroying a pristine environment * a new genus of

cave wētā Caves or caverns are natural voids under the Earth's surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock sh ...

or tokoriro, '' Occultastella morgana,'' informally dubbed the Denniston white-faced wētā * a beetle, another moth, a wingless wasp, and three spiders File:Powelliphanta-patrickensis-1200.jpg, '' Powelliphanta patrickensis'' File:Powelliphanta-augusta-hero.jpg, ''

'' File:Arctesthes avatar m.jpg, Male '' Arctesthes avatar'' File:Occultastella morgana.jpg, '' Occultastella morgana''

Conservation

The northern part of the plateau has been heavily modified by Solid Energy's large

Stockton mine Stockton Mine, on the Stockton Coal Field, is New Zealand's largest opencast mining operation. The entrance to the mine is at the former settlement of Stockton. Extent The coal field is situated between 5 and 10 kilometres linear distance ...

. In 2011 Australian-based

Bathurst Resources Bathurst Resources, along with a number of subsidiaries, is a coal mining company in New Zealand that was established in 2010. History The company was originally based in Perth, Western Australia, and incorporated on 30 May 2007, listing on the A ...

gained consents for the Escarpment Mine Project in the southern part of the plateau towards Mt Rochfort, which would involve stripping and "relocating" the surface vegetation, removing and stockpiling the sandstone layer, and creating an open-cast mine. The land would supposedly be rehabilitated after mining, but the unique drainage and soil conditions, and thus much of the biodiversity, would be destroyed. This created years of conflict between councils and governments wanting short-term economic relief for the people of the West Coast, and those who valued the unique and delicate ecosystem of the plateau. Environmental groups fought the consents in court for two years but they were upheld by the

Environment Court The Environment Court of New Zealand () is a specialist court for plans, resource consents and Natural environment, environmental issues. It mainly deals with issues arising under the Resource Management Act 1991, Resource Management Act, meani ...

in 2013.

Forest and Bird Forest & Bird (), also known by its formal name as the Royal Forest and Bird Protection Society of New Zealand, is an environmental organisation specialising in the protection and conservation biology, conservation of New Zealand's indigenous F ...

proposed a 5900 ha reserve on the plateau, and organised a bioblitz to learn more about its species diversity. Bathurst was given consent to mine the plateau in 2014 by the

, in exchange for $21.9 million in compensation spread over seven years. During the planning process the price of coal dropped significantly, and the closure of the Holcim cement works at

Cape Foulwind Cape Foulwind is a headland on the West Coast of the South Island of New Zealand, overlooking the Tasman Sea. It is located west of the town of Westport. There is a lighthouse located on a prominent site on the headland. A walkway beginning ...

– the main market for the coal – made the project uneconomic; Bathurst suspended its operation in 2016. Environmentalists proposed national government investment in long-term sustainable economic development of the West Coast Te Tai Poutini to end the peoples reliance on the

boom-and-bust Business cycles are intervals of general expansion followed by recession in economic performance. The changes in economic activity that characterize business cycles have important implications for the welfare of the general population, governmen ...

mining industry, but this has not come to fruition under either Labour or National Coalition governments. Seventy protestors camped on Denniston Plateau in April 2025 and climbed into coal buckets used to transport coal via aerial ropeway from Stockton Mine to

Ngakawau Hector and Ngakawau are two lightly populated settlements located at the mouth of the Ngākawau River in the West Coast region of New Zealand. Both settlements are situated on State Highway 67 between Westport and Karamea. Despite a low popul ...

for loading onto trains. They were protesting the proposal to expand the Escarpment Mine Project under the

Fast-track Approvals Act 2024 The Fast-track Approvals Act 2025 is a New Zealand Act of Parliament that seeks to establish a permanent fast track approvals regime for a range of infrastructure, housing and development projects. The Bill is part of the Sixth National Governme ...

. Bathurst Resources claimed Stockton Mine was nearly depleted, and expanding the mothballed project on Denniston Plateau would extend coking coal production by 20 years, employing 390 people. The protestors claimed the 20 million tonnes of coal produced equated to 56 million tonnes of carbon emissions, and would threaten unique species on the plateau that were found nowhere else.

References

External links

{{Buller District Landforms of the West Coast Region Buller District Plateaus of New Zealand