Caples Sandstone is the dominant rock of the Caples and Greenstone Valleys and the surrounding mountains. This was deposited on the sea floor as layers of mud and sand on top of volcanic rocks about 220-270 million years ago.

The sandstone is tough, erosion resistant rock which has been tilted and now stands more or less on end. A band of blackish serpentine, known as the Greenstone Melange, is wedged between the sandstone. It crosses the lower Caples and Slip Flat area of the lower Greenstone.

The river terraces and flats are made of local glacial and river gravels and outwash.

During the Ice Ages the enormous Hollyford Glacier reached as far as Martins Bay on the west coast. It flowed over Key Summit on the main divide where it branched into the Eglinton Valley and the Greenstone Valley. The Greenstone Valley glacier split into two at the Sly Burn and reached as far as Mavora Lakes in the south and Lake Whakatipu in the east.

Native plants

The forests in the Caples and Greenstone Valleys are southern beech, or Nothofagus spp. Large leaved red beech trees prefer richer soils of alluvial fans at low altitude. Small smooth leaved mountain beech predominates at higher altitudes. Silver beech occurs throughout the valleys. In some summers the bands of different beech trees across the valley sides can be seen.

The forest under storey is characterised by ferns and small shrubs and trees such as the peppery tasting horopito.

The open grassy river flats have always been clear of forest, as frequent frosts in winter stop the forest encroaching onto them.

Since the flats have been farmed the original grasses and tussocks have mostly been replaced by introduced grasses. Despite this there are still some extensive areas of tussock remaining in the mid and upper Greenstone Valley.

Prominent patches of scrubby celery pine and bog pine occur in places on the river flats. Inaka or Dracophyllum, tussocks and stunted beech trees are found on McKellar Saddle.

Native animals

Insect-eating birds such as tomtits/miromiro, fantails/pīwakawaka, rifleman/titipounamu, brown creeper/pipipi and South Island robin/kakaruai thrive in the beech forests which are rich in invertebrate life.

Kākāriki, or parakeet, the rare mōhua, or yellowhead, and kākā can be heard in the forest throughout the Greenstone Valley. Kea are sometimes seen at the upper end of the Caples track, and falcon/käreärea hunt the flats and forest edges.

Whio, or blue duck, are found in fast flowing streams and rivers in the valleys. The noisy paradise ducks/pūtakitaki are conspicuous inhabitants of the river flats.

South Island kōkako, which are considered extinct, kiwi and native bats have been reported from the Caples and Greenstone Valleys, but there have been no recent confirmed sightings.

The Greenstone Valley and the Hollyford Valley were the easiest access routes between the West Coast and Central Otago. They were discovered and widely used by the Waitaha, one of the earliest groups of settlers in the region. They were followed by Kati Mamoe and Ngāi Tahu in succession, travelling from Lake Whakatipu to the West Coast in search of pounamu, or greenstone.

Early West Coast Ngati Wairangi also used the route as they sought pounamu from the Dart Valley. Pounamu was valued as a material for tools, weapons and ornaments. The Otago pounamu was the especially valued pearly grey-green variety, and was made into tools and weapons of great mana (status).

No Māori archaeological sites have been found within the Greenstone and Caples Valleys.  About 20 sites have been found beside the Dart/Te Awa Whakatipu and Rees/Puahere Rivers, and on Pigeon Island/Wāwāhi Waka, opposite the mouth of the Greenstone Valley.

The first Europeans to view the area, in 1862, were Southland runholders David McKellar and George Gunn. In 1863 gold prospector Patrick Caples was the first European to cross from Lake Whakatipu to the West Coast.

For a long time the pack route up the Greenstone Valley was the only land route to the West Coast and the settlement at Martins Bay. The first runholder began farming the Caples Valley in 1880, and the original homestead of Birchdale Station still stands.

During the 1880s both valleys were plagued by rabbits, as was much of New Zealand at that time. The Greenstone Valley and the Pass Burn were used as stock trails for early runholders at the head of Lake Whakatipu.

In the late 1800s Lake Rere was a popular destination for steamer excursions. The steamer would stop at the Elfin Bay wharf while the tourists walked to the lake.

Ngāi Tahu Land Settlement - Kā Whenua Roimata

As part of the Crown’s settlement of Ngāi Tahu’s historic land claims, three high country stations at the head of Lake Whakatipu have been transferred to Te Rūnanga o Ngāi Tahu. Te Runanga are to transfer 4100 hectares of mountain land in the southern Ailsa Mountains and the southern Humboldt Mountains back to the Crown by way of gift to the people of New Zealand. This land is now known as Kā Whenua Roimata, which translates as “the lands of tears”.

Te Rūnanga o Ngāi Tahu are also to lease back to the Crown in perpetuity, as conservation areas, other significant portions of the stations, mainly in the Mararoa catchment. Also, public foot access by means of covenants is available around Lake Rere, to Scott Basin, and through the freehold portions of the properties in the Greenstone and Caples Valleys.