Volcanic adventure in rugged 4WD
Strangely shaped conical hills in Taranaki point to a violent volcanic past, and to a future with real tourism potential, Rob Maetzig, writes.
Those of us aboard the Ford Ranger looked at the strangely shaped grasscovered hill ahead. Perfectly round at its base and with steep sides, the conical mound looked as though it had been formed by a giant pair of hands, just as a child would do with sand on a beach.
Could the Ranger make it to the top?
The model was a flash Wildtrak version with all the luxuries and plenty of grunt via its turbocharged diesel – but it also had 18-inch wheels shod with road-going 265/60 R18 tyres.
We tried. With the big Ford in 4WD Low, and with the electronic rear differential lock activated, we took on the hill. Maybe we got halfway up the strange grassy incline.
We would probably have got to the summit if we’d had fewer than four aboard, proper offroading tyres, or maybe even reduced the amount of air in the existing tyres. But we couldn’t get there. So after trying three times we coasted backwards down the hill, got out and walked to the top instead.
And once we’d got there we were presented with a unique view – a mass of dozens and dozens of similar-shaped conical hills, spreading all the way to the coastline in the distance.
We were in the middle of what is known as the Mt Taranaki volcanic debris avalanche – the remnants of enormous landslides that occurred thousands of years ago and deposited debris at least 30 metres deep over more than 250 square kilometres of the Taranaki ring plain, all the way to the sea up to 40km away.
The geological information about all of this is mind-boggling; as in one side of an entire mountain slipping away.
Experts say that what is officially known as the Egmont Volcano began forming about 70,000 years ago, but that about 50,000 years ago the original cone collapsed and spread massive amounts of debris to the Taranaki coastline.
A second cone then built up, but 23,000 years ago this also completely collapsed, once again sending down an enormous avalanche. By about 17,000 years ago a third cone had built, but it also collapsed, sending a giant lahar down the mountain’s flanks.
Thousands of years later, the results of these gigantic avalanches are all still there to see. Someone once said that large parts of the land surrounding Mt Taranaki are like what happens if a pot of vegetable soup is spilled – once the water drains away, all the debris remains.
And that’s what the conical hills are.
Today they are all covered in lush grass, because the soils of the Taranaki ring plain are fertile, free-draining, deep, volcanic ash soils commonly known as yellow brown loams, perfect for pastoral use, particularly dairy farming.
It’s also great country for fourwheel driving – and that is leading to the potential development of a commercial eco-tourism operation, taking visitors to the best places to see first-hand not only the results of what happened all those tens of thousands of years ago, but to get a rather disturbing insight into what is continuing to happen today.
The Okato Lions Club in northwestern Taranaki has among its membership farmers and business people who own land right in the middle of the path of the volcanic debris avalanche, and the club has begun hosting excursions through the countryside.
Our Ranger was almost ideal for the task. New Zealand’s most popular new vehicle in 2015 and a virtual certainty to again be the top-seller in 2016 – the final new vehicle registration figures for the year are expected to be released about now – it is an outstanding example of what could be described as the gentrification of the one-tonne ute.
These vehicles really are refined. In the case of the Ranger, during 2016 it received improvements including upgrades to its powertrain so it meets Euro V emissions standards, and introduction of Ford’s Sync3 invehicle communications and entertainment platform that is faster and easier to use with enhanced response to voice commands from the driver.
But underneath all these niceties there remains a very capable ute.
Built on an ultra high-strength chassis, the Ranger is powered by a five cylinder 3.2-litre turbocharged diesel that develops 147 kilowatts of power and 470 newton metres of torque. At the Wildtrak level the big Ford is 4WD with High and Low ratios and an elock rear differential which locks the rear wheels during tough going.
The truck also has a 237mm ground clearance and 800mm wading depth, which is sufficient to take on some substantial river and stream crossings.
Steep climbs uphill aside, the Ranger Wildtrak easily took on the remains of the volcanic debris avalanches – the Okato Lionsorganised expedition was designed more for enjoyment and education than for heart-in-themouth offroad work.
Anyone who didn’t feel confident about going up and over any of the conical hills simply drove around them, and river crossings were easy enough.
The expedition culminated in a drive to a place that is a dramatic reminder that if anyone thinks massive erosion isn’t continuing to occur within what is now Egmont National Park, should think again.
On the eastern boundary of the mass of conical hills there is a river called the Stony, which is said to be the fastest-flowing river in New Zealand.
After percolating through Ahukawakawa, a giant sphagnum swamp between the mountain and Pouakai Range, then pouring over Bell’s Falls, the Stony’s water rushes downhill towards the river’s mouth west of Okato.
But near the headquarters of the Stony there is a smaller watercourse called the Pyramid Stream, which flows down the flanks of Mt Taranaki below two features called Little Pyramid and Big Pyramid.
It’s there that massive erosion is currently taking place – cliffs more than 40m high are crumbling, and all of the gravel and sand is flowing downhill towards the Stony.
And when that combines with very heavy rain that occurs on the mountain, then the Stony can flash flood and become extremely dangerous.
Our 4WD expedition crossed paddocks to the upper reaches of a place called Blue Rata Reserve, where we were shown recent results of this erosion and flooding.
In 1998 and again in 2008 the flooding was so severe it blew out several hectares of land and threatened to send the Stony River’s water down a new course, straight towards the township of Okato, population 600.
Will it happen some time in the future? Who knows? But then again, who would have thought an entire mountain could have collapsed?
But it’s all there to see – and that’s what makes the Okato Lions-organised 4WD tours of the Mt Taranaki volcanic debris avalanche so fascinating.
It looks at what has happened in the past, and what has every prospect of happening in the future. It has real potential for development as a unique ecotourism venture.
Our 4WD expedition crossed paddocks to the upper reaches of a place called Blue Rata Reserve, where we were shown recent results of this erosion and flooding.