593
Accessibility: MODERATE
WHAT'S HERE?
Stalactites and columns in Ngarua Cave, Photo Barbara Williams
A tourist cave with lots of interesting features including a great variety of formations as well as a display of moa bones.
LEARN ABOUT IT
Stalactites in Ngarua Cave, Courtesy of Wikimedia
The road over Takaka Hill passes through a karst (weathered limestone or marble) landscape - a magnet for cavers. The area around Ngarua Marble Cave is a dissected plateau at around 650 m pocked by enclosed depressions (dolines) and incised by dry valleys.
Limestone is predominantly made of calcium carbonate, which is susceptible to being dissolved by slight acidity in rainwater and groundwater. Rock solution on Takaka Hill removes an amount equivalent to a thickness of 100±24 mm per 1000 years and, over a long time period, this has led to the opening of cracks (joints and faults) in the bedrock and the creation of passageways and tunnels that are conduits for underground streams.
In places, the dissolved calcium carbonate gets re-deposited by dripping water on the walls and floor of the cave to form a wide variety of formations such as curtains (or shawls), stalactites (hanging down), stalagmites (growing upwards), columns where they have joined together, and straws.
The cave was originally formed by an underground stream that flowed close to the water-table (the top of the water saturated zone in the bedrock), but the modern water table is now about 550 m beneath the cave at the level of Riwaka Spring in the valley below. This indicates that the water table has dropped since the cave was formed. The reason for this is that the cave has been raised by tectonic uplift above the level at which it first formed. The Riwaka Spring also lowered in elevation as its valley incised to keep pace with uplift.
On Mt. Arthur, another marble mountain further south, uplift occurred at a maximum rate of 0.4 m/1000 years. If a similar uplift rate applies to Takaka Hill, then Ngarua Marble Cave could have formed about 1.4 million years ago.
Limestone is predominantly made of calcium carbonate, which is susceptible to being dissolved by slight acidity in rainwater and groundwater. Rock solution on Takaka Hill removes an amount equivalent to a thickness of 100±24 mm per 1000 years and, over a long time period, this has led to the opening of cracks (joints and faults) in the bedrock and the creation of passageways and tunnels that are conduits for underground streams.
In places, the dissolved calcium carbonate gets re-deposited by dripping water on the walls and floor of the cave to form a wide variety of formations such as curtains (or shawls), stalactites (hanging down), stalagmites (growing upwards), columns where they have joined together, and straws.
The cave was originally formed by an underground stream that flowed close to the water-table (the top of the water saturated zone in the bedrock), but the modern water table is now about 550 m beneath the cave at the level of Riwaka Spring in the valley below. This indicates that the water table has dropped since the cave was formed. The reason for this is that the cave has been raised by tectonic uplift above the level at which it first formed. The Riwaka Spring also lowered in elevation as its valley incised to keep pace with uplift.
On Mt. Arthur, another marble mountain further south, uplift occurred at a maximum rate of 0.4 m/1000 years. If a similar uplift rate applies to Takaka Hill, then Ngarua Marble Cave could have formed about 1.4 million years ago.
HAVE A LOOK!
Stalagmite, Ngarua Cave, Courtesy of Wikimedia
All caves have their own character. As well as identifying the typical flowstone (dripstone) cave deposits, it is interesting to see them in their unique combinations and arrangements. There are also some moa bones on display in the cave, which are probably Holocene in age (less than about 10,000 years)
-41.0194293135584
172.900227784412
Directions/Advisory
Situated on the Marble Mountain in the Takaka Hill range, 1/2 hr drive from Motueka on SH 60 towards Takaka and Golden Bay. Sign very easy to see from the road.
Not possible for wheelchairs. Cafe open in summer.
Google Directions
Accessibility:
MODERATE
Price per adult is $30, for children aged between 5-15 it is $10 and under 5s are free. Check the website below for opening hours and tour times. In winter, June to Sept, booking is essential.
Visits are guided and take about 45 minutes. The cave passage is about 300m long.
Features
Sedimentary
Landform
Geological Age
Arthur Marble 2 of the Mount Arthur Group, about 450 million years old. The cave may be about 1.4 million years old
Zealandia Evolution Sequence
Western Province (Paleozoic growth): 500 – 110 million years ago
Links