Oparara Basin facts for kids
The Oparara Basin is a special natural area in the South Island of New Zealand. It's about 20 kilometers north of Karamea in the West Coast Region. This amazing place is part of the Kahurangi National Park.
The Oparara Basin is famous for its huge natural rock arches and a network of caves filled with ancient fossils. It's also home to a beautiful, untouched temperate rainforest. Many unique plants and animals live here, some of which are found nowhere else in the world!
Contents
A Look Back: History of the Oparara Basin
The Oparara Basin has been mostly untouched by people for a long time because it's quite isolated. However, maps from the 1880s already showed where the big natural rock arches were.
Early Logging and Roads
In the late 1800s, people started cutting down native trees here. A sawmill called McCallum's was built. As they cut down more trees, they had to build roads deeper into the rugged forest to reach new areas. Keeping these roads open became very expensive. Eventually, the sawmill closed down. Even after that, some selective logging continued until it was completely stopped in 2002.
Protecting the Basin
When the sawmill closed, a big effort began to protect this special area. People wanted to make sure the basin and its roads were looked after. This led to the creation of the Oparara Valley Project Trust. On October 1, 2004, they bought the land to protect it forever.
Discovering Ancient Secrets in the Caves
Miners and deer hunters often talked about amazing rock formations in the Honeycomb Hill area. But it wasn't until the 1980s that a group called the Buller Caving Group explored the area properly. They found 70 entrances to a huge cave system, with about 13 kilometers of tunnels!
These explorations were very important for science. They found the largest collection of bird fossils ever discovered in New Zealand.
New Paths for Visitors
A big project finished in 2009. It created a 30-kilometer network of walking and mountain biking tracks. This made it much easier for visitors to explore more of the Oparara Basin. Before this, most tourists only visited the Heaphy Track.
Lord of the Rings Place Names
Some places in the Oparara Basin have names inspired by the famous books, The Lord of the Rings! You can find places like Galadriel Creek, Nimrodel Creek, and Moria Gate Arch.
Geology and Climate: How the Basin Was Formed
The Oparara Basin sits on very old granite rock, which is about 350 million years old. About 35 million years ago, a thin layer of limestone (15-60 meters thick) covered this granite. The very top layer of the ground is a blue-grey mudstone.
The Power of Water and Nature
The limestone layer has been greatly shaped by the weather. The area gets a lot of rain every year, sometimes up to 6 meters! The roots of the many plants also help break down the limestone. Earthquakes and changes in sea level over millions of years have also helped create the unique rock formations you see today.
The basin has many features typical of a karst landscape. This means it has lots of impressive rock arches, caves, and places rich in limestone fossils.
Ancient Animals: The Fauna of the Past
The Oparara Basin is famous for its amazing discoveries of ancient animals. The Honeycomb Hill Cave area was found in 1976. By 1982, it was recognized as a globally important site for paleozoology (the study of ancient animals). This is because scientists found bones of many species that died out after humans arrived in New Zealand.
Incredible Fossil Finds
In 1984, the first big search for bones found skeletons of fifty birds. Most of these were extinct species!
The first and most complete bones of the giant Haast's eagle were found here. You can see them on display at the National Museum of New Zealand in Wellington. Other finds included skeletons of the Lyall's wren, New Zealand owlet-nightjar, Aptornis otidiformis, and nine different types of moa. You can even see moa skeletons inside some of the caves! Scientists also found bones of amphibians, lizards, and about 40 different kinds of snails.
Why So Many Bones?
So, why are there so many well-preserved bones and skeletons here? The holes in the limestone acted like traps, catching the bones. The limestone also protected them from heavy rains. The caves have steady temperatures, and the bones are chemically similar to limestone, which helped keep them safe for a very long time. Some intact skeletons found here are more than 20,000 years old!
Protecting Honeycomb Hill Cave
In 2008, the Kahurangi National Park was made 10 hectares larger to fully protect the Honeycomb Hill Cave system. Honeycomb Hill Cave is a special, protected area. You can only enter with a permit. The Oparara Trust offers guided tours to this amazing place.
Today's Amazing Animals and Plants
Today, the Oparara Basin is a vital home for many unique species. Some of these are endangered, and some are found only in this area.
Unique Snails and Spiders
The Oparara Basin is the only place where two types of snails, Powelliphanta marchanti and Powelliphanta annectens, have been found. The Powelliphanta marchanti is strictly protected; you're not even allowed to collect its empty shells! The Powelliphanta annectens has only been found near the Oparara River.
Two types of spiders, Oparara karamea and Oparara vallus, also live only here. The caves are home to the protected Nelson cave spider, glowworms, and the New Zealand greater short-tailed bat.
Rare Birds
The Oparara Basin is also a home for the blue duck and the great spotted kiwi. Both of these birds are endangered. You can also find the unique kea, weka, New Zealand falcon, and paradise shelduck here.
The Forest Floor
Most of the area is covered in a mix of beech and podocarp trees. The forest floor is like a thick carpet of mosses, ferns, and smaller plants. Because the soil can be shallow, these plants often have to push their roots through cracks in the limestone to hold on. This actually helps to slowly break down the limestone even more!
A Special Moss and Red Water
A very rare moss called Epipterygium opararense was named after this area. It grows near the entrances of the arches and caves. Even with careful searching, only about 175 of these tiny plants have been found near a path.
Many plants in the area release natural chemicals called tannins when they break down. These tannins turn the water in the streams and rivers a brown or reddish color, like tea! The color can change depending on the season and how much rain has fallen.