Introducing the Oparara
Tucked away in a corner of Kahurangi National Park, the Oparara has a magic all of its own, born of a million years of undisturbed isolation.
The Oparara’s affinity with Tolkien’s mystical forests is today reflected in the Lord of the Rings names now scattered throughout the Basin.
Rich unspoiled rainforest stretching across a broad valley floor, three magnificent arches sculpted by the Oparara River, bush-fringed streams stained the colour of billy tea from the humic acids washing down through the soil, and an underground treasure hidden away in a highly complex cave system, combine to make this remarkable area one of immense national and international significance.
The Honeycomb Hill Caves...
Are situated in the 'Honeycomb Hill Caves Specially Protected Area' in the Oparara Basin, Karamea, in the Kahurangi National Park.
The Honeycomb Hill caves lie some 300 m above sea level in the Oparara Valley, a broad shallow valley at the head of the Oparara River just north of Karamea. The Basin itself is relatively sheltered.. Some six metres of rain pour into the area each year.
The area was certainly known to our early mapmakers, and the “natural bridges” or arches are marked on old Karamea maps dating back to the 1880s.
Goldminers and deerstalkers roaming the Oparara came back with some pretty tall tales of this remarkable country, until Forest Service staff Norman Stopforth and Barry Chalmers, working in the area in the late 1970s, stumbled across the entrance to Honeyflow Stream.
Subsequent investigation by the Buller Caving Group in the 1980s led to international scientific interest and National Museum involvement, when it was revealed that the caves had the most varied collection of subfossil bird bones ever found in New Zealand tucked away in their depths.
Since Forest Service days a guiding concession has been run by private operators, until purchased by the Oparara Valley Project Trust on October 1 of 2004.
The Oparara Basin is formed from a bed of 350 million year old Karamea granite overlaid by a narrow belt of limestone, with a layer of blue-grey mudstone (or papa) on top.
The Honeycomb Hill Caves tunnel system was formed over the last million years, while the limestone itself, from 15 to 60 m. thick, is approximately 35 million years old, formed from deposits of shell debris when the area lay under the sea.
Wrinkling, bending, faulting and glaciation, combined with changes in sea level and erosion, have left us with the geological structure we know today. It is the easily eroded limestone which gives the valley so many of its spectacular features and the caves their cathedral-like passages.
Formations & fossils
This extensive subterranean wonderland of conventional dripstone and flowstone formations also includes a profusion of very beautiful and delicate rarer features known variously to cavers as cave coral, petals, pearls, rimstone pools, elephants feet, moonmilk, and even shawls and straws, depending on how they were formed.
Moa bones in the Honeycomb Hill CavesThe caves are also home to the largest and most varied collection of subfossil bird bones ever found in New Zealand. More than 50 bird species, many of them extinct, have been recorded.
These include nine different moa species, the giant flightless goose, Finsch’s duck, the giant NZ eagle, the giant flightless rail, the flightless coot, the NZ owlet-nightjar and Stephen’s Island wren, as well as other rare NZ birds such as the kakapo, kokako, takahe, and yellowhead.
Petrel and shearwater remains show that these seabirds also once nested in the valley.
Many of the bones were washed into the caves as carcasses by rivers and streams, while others such as moas fell through holes in the cave roofs.
As limestone and bones are very similar in their chemistry, and the temperature inside the caves steady, many of the bones are perfectly preserved, adding to the significance of their discovery, since many date back some 20,000 years.
There are also the bones of native frogs and lizards, and the remains of 40 different land snail species, finds of immense scientific value in the study of the evolution of more advanced species.
Fauna & flora of the Oparara
Underground but very much alive is NZ’s largest spider, (hunky but harmless), Spelungula cavernicola, a brown furry body sprouting legs that give it an overall size of up to 15cm. Spelungula find their prey by vibration - cave weta mostly, while their egg sacs hang from the ceiling like miniature golf balls.
Glowworms, with origins dating back 80 million years, light up the eternal darkness, attracting prey with their luminescence, while tiny ant-like troglobites with suction pads on their feet shimmy across the wet walls.
The twilight cave entrances are fringed and draped with delicate mosses and algae. The area surrounding the caves is heavily forested with a stunning mixture of beech/podocarp forest, thickly coated in moss, and it is this beech forest that generates the humic acids that stain the streams a billt tea colour, and also creates high acidity.
The diverse forest types support a wide range of native birdlife, protected under the Conservation Act of 1987, including the great spotted kiwi, the rare blue duck, kaka, NZ falcon, kea, weka, pigeon, robin, fantail, parakeet, paradise duck, and tomtit, to name a just a few, while it is thought that the kokako may still be present in the area.
The rare lesser short-tailed bat has also been recorded in the vicinity, while the large carnivorous land snail, Powelliphanta annectens is found throughout, but in greater numbers in and adjacent to the areas of limestone.
The snails are in turn eaten by wekas, keas, rats and even possums, and damaged shells are common. Again, both snails and shells are protected.