Tuesday, 4 August 2015

Hauraki Rail Trail – The Karangahake Gorge

Before we left Waihi on Monday 20 July, we went to have a look at the Martha open cast mine. This is a huge, impressive pit from which gold- and silver-containing ore is mined. It is 700 m wide and 260 m deep.

Waihi has a long history of gold mining, going back to the discovery of gold in 1878. Until 1952, mining at the Martha Mine was underground. Over those years, seven vertical shafts were sunk, the deepest down to 600 m, and radiating from them was a network of 175 km of tunnels on 15 horizontal levels.

In 1952 the mine was closed, as the price of gold had dropped. But in the 1980s the price picked up again, and since 1987, the Martha Mine has operated as an open pit.

The Martha Open-cast Mine (photo by John)

The other side of the mine (photo by John)

There is a 4 km track around the rim of the mine that is open to the public, and we probably should have biked around the perimeter, as I believe there are interpretation panels that would have provided interesting information about the mine and its activities. However, there appeared to be no actual activity in the mine that we could see, and there were other things we wanted to do that day.

Now that I am writing this up, and have been reading about the history of Waihi and the mining operations, I think we will just have to make a return visit some time, so that we can ride around the rim, take the Mine Tour, and visit the Waihi Museum. 

On the rise between Waihi’s main street and the rim of the mine, stands the historic Cornish Pumphouse. This was built in 1904 to house steam-driven pumping machinery that removed water from the mines until 1914, when electricity took over operation of the pumps.

The historic Cornish Pumphouse (photo by John)

Looking through the pumphouse

After the pumping machinery was removed in 1930, the building became derelict. In 2006 the building – by now protected by the Historic Places Trust – was moved 300 metres, away from land that had become unstable following the collapse of an adjacent mineshaft.

The Pumphouse was moved in 2006 (click to enlarge)

Also nearby was a reconstructed “poppet head” – a construction built over a mine shaft to raise or lower a cage to transport men, materials and ore into and out of the mine.

John by the poppet head

After this visit, we drove to Waikino Station, from where we intended to bike the Karangahake Gorge track. The café in the beautifully restored station building was a charming place to have morning tea. The room was decorated with local memorabilia, and locally made crafts (for sale).

The Waikino Station Café (photo by John)

Old suitcases on the platform give the station an authentic feel (photo by John)

Just as we were getting the bikes out of the car, a couple of railway maintenance people arrived, with a bogie carrying a digger, and an engine pushing goodness-knows-what. Of course we went over for a chat. They had been working on clearing the track, and said that the train would be running later that day. Unfortunately the timing did not fit into our plans.

One of the men also said that the Paeroa to Thames part of the Hauraki Rail Trail, that we had biked the previous day, was the most boring track he had ever biked – being straight and through a flat landscape “with nothing interesting to see”. Luckily we didn’t find it so.

Track maintenance machinery

Leaving the car in the station carpark, we crossed the bridge and carried on up the trail along the river, from where we had got to two days earlier.

The Ohinemuri River (photo by John)

Heading towards the Karangahake Gorge

It was very pleasant riding on a wide smooth gravel track. The scenery was becoming wilder, and soon we arrived at the Karangahake Tunnel, which is approached across a bridge over the Ohinemuri River. The tunnel disappears under the road (SH2).

The bridge over the Ohinemuri River leads straight into the tunnel (photo by John)

The Karangahake Gorge, viewed from the bridge (photo by John)

The long tunnel (1086 m), completed in 1905, was built to transport mining materials and gold in and out of Waihi. Although there are some lights in the tunnel, they are quite widely spaced and do not light it up very well. Our bikes have excellent lights on them, and we had brought good torches, which helped.

Even so, the tunnel caused John some serious problems with his balance, and although he did manage to bike the whole way (rather than getting off and walking), he emerged at the other end looking rather green round the gills. The imbalance makes him feel quite nauseous. And to make things worse for him, there was another high, former railway bridge at the exit of it. “God, that was awful. I’m not going back through there”, he said.

The Karangahake Tunnel is over a kilometre long (photo by John)

Luckily we did not have to go back through the tunnel, as there was a loop track to get us back to Waikino. On the way, though, there was plenty more to see.

The track led us past the remains of the Crown Mines Battery. This was a gold and silver processing plant, the first in the world to use cyanide treatment (sounds like an environmental disaster, doesn’t it), and apparently very successful at the time.

The remains of the Crown Mines Battery

Looking upriver towards the bridge that joins the trail to SH2 (photo by John)

We arrived at the Karangahake junction, where there was access to the trail from SH2, a park and several track options. We followed a sign that pointed towards the Windows Walk. We didn’t know much about that walk, except that I had read that this was something we “should not miss”.

The track led along the bank of the Waitawheta River, and at first it was quite reasonable, but some distance down, it became very narrow, and we had to dismount and walk our bikes along the path.

At first the track along the Waitawheta River was quite manageable … (photo by John)

… but beyond this point it became too narrow to bike (photo by John)

The track was literally carved out of the gorge walls, only barely wide enough for us walking beside our bikes. But we kept going, because the place was so beautiful, and we wanted to know where it would end up. At various places we could peer into mining tunnel entrances.

The very narrow path is carved out of the soaring gorge walls (photo by John)

One of the mining tunnels (photo by John)

We went across a suspension bridge, and soon after, we arrived at some steps with a sign pointing up towards the Windows Walk. This is where we decided we had gone far enough with our bikes in hand. We didn’t want to leave the bikes there, although there wasn’t another soul around, and they would have been quite safe. But the Windows Walk involved lots more tunnels, which John was not keen to explore. So we turned around.

John climbed some way up the steps – just for the view (photo by John)

The return trip across the suspension bridge

Soaring canyon walls showing some of the “windows”, behind which lurk the mine tunnels

Back at the Karangahake junction, we followed direction to the Karangahake Tunnel Loop Walk, which we hoped would take us back to Waikino. However we first had to cross a bridge that did not appear to be designed for bikes. We had to carry the bikes up about a dozen steps. A bit of a mission with our quite heavy e-bikes. John managed to carry his bike up (just), but I needed help.

We had to carry our bikes up the steps to get across this bridge over the Waitawheta River
(photo by John)

The remains of the Woodstock Battery (photo by John)

Once across, we found another lot of battery remains, the Woodstock Battery. I had serious misgivings about the suitability of the track for biking – it was narrow, very bumpy with lots of rocks and tree roots, and quite steep in places.

While pushing our bikes up the hill, we were overtaken by a walker who was obviously a local, and I asked him if the track ahead was OK for bikes. He told us that it would be OK further along, so we persisted. I must say that pushing a fairly heavy e-bike uphill on a lumpy track was hard work, even with the walk-assist! (Walk-assist is a feature which propels the bike along at 6 km/hr, making it easier to push it uphill, but with my gammy hand I find it hard to keep a finger on the button that makes it work.)

At one stage, having gone over a hill and come back down to river level again, before heading uphill again, the track became so narrow that we couldn’t even walk beside our bikes for fear of keeling off the edge. We had to carefully manoeuvre them ahead of us. A bit scary!

The track became too narrow to walk beside our bikes (photo by John)

Finally, finally, we arrived at the end of the loop, and we re-joined the main track on the other side of the tunnel. It was then an easy ride back to Waikino.

Back on the track to Waikino (photo by John)

Before going back to the car, we explored the historic Victoria Stamping Battery site.  In 1898, this was the largest quartz crushing plant for gold extraction in Australasia. It processed ore from the Martha Mine. When the mine was closed in 1952, operations continued on a reduced scale, but then ceased in 1955. Now, all that’s left are the foundations and various bits of machinery.

Would this be part of an ore crushing machine?

This link provides a very clear map of the site. The most interesting structure was the remains of the cyanide agitation tanks (No. 7 on the map). It is like a gigantic honeycomb of concrete hexagons with enormous steel funnels coming down into them. I don’t pretend to understand what the process was, but the construction was fascinating. No matter which “window” you looked through, you could always see across and sideways to the other side.

The cyanide agitation tanks complex

One of the huge, magnificently rusty funnels (photo by John)

This shows the hexagonal construction of the “cells”

Somehow, this reminded me a bit of a cathedral’s buttresses

We wandered around the lower part of the site, looking at foundations of buildings and what I think may have been a tail race, to carry water back to the river.

Foundations of buildings (photo by John)

The tail race – I think (photo by John)

Next we climbed up a level to where there is a museum in what was the transformer house. The museum was not open (open Wednesdays and Sundays only). There was a narrow tram track (on which people can have rides on museum days) around the site, and a number of wagons and wheel bases were on display.

The transformer house and various bits of machinery (photo by John)

One of the ore wagons (photo by John)

We climbed still further up the hill to the ore kilns. These are huge holes in the ground where gold-carrying quartz was heated to make it easier to crush. Tunnels ran underneath to collect the rocks, for the next process.

The ore kilns are now under cover to preserve them

A gantry allows people to look down into the kilns (photo by John)

The kilns are lined with bricks, but are now overgrown with mosses and ferns
(photo by John)

An information board explains the process (click to enlarge)

View from the ore kilns site. You can just make out the hexagonal construction of
the cyanide agitation tanks in the middle of the top third of the photo.
Click to enlarge (photo by John)

On our way back down to the bridge to take us back to the car, we went past lots more rusty bits of machinery, scattered about the lower site.

More rusty relics – and I don’t mean John!

In completing the Karangahake Gorge Loop, we did not get to ride all the way to Paeroa, which had been our original plan. We had biked only 17 km, and some of that was not even biking, as we had to walk quite a bit of it. I think we will definitely have to come back and explore this area some more.

But now it was time to head to our next destination – Tauranga or Mount Maunganui, where we intended to spend a day exploring the city's cycle tracks. We stopped at Waihi Beach on the way. Very beautiful, and very popular in the summer, but the place was pretty much dead at this time of the year.

Waihi Beach (photo by John)

We found a motel in Mount Maunganui, and went for a walk near the beach in search of dinner in the evening.

The beach at Mount Maunganui at dusk (photo by John)

Finally, here is a photo of John’s “charging station” at our accommodation – five devices off just two power points: two bike batteries on one power point, and his laptop, iPad, and iPhone on the other.

John’s charging station (photo by John)

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