STUDY SITES FOR KARANGAKAHE
There are three study sites suitable for school students:
1
A good site for students to investigate the geology of Karangahake
rocks (see page 24).
2
Have a go at measuring water quality here (see page 25).
3
There is a prominent quartz vein here – making it a good location to
discuss mining. Looking over the river, students will also be able to
see the ‘windows’.
to Paeroa
hall and
parking
2
railway tunnel
Ohinemuri River
Karangahake Reserve
main car park and
toilets
to Waihi
2
2 River Survey
1 Karangahake Rocks
Study
The ‘Windows’ Track
(return the way you came)
Waitewheta River
Karangahake Walkway
(follows river to Waikino Visitor
Centre)
track under
development
3 quartz vein
in cliff
Key:
(short tunnel)
= bridge
= walking track
2
= State Highway 2
Pumphouse
(no access)
N
Please note: this map has
not been drawn to scale.
= tunnel
23
IV. SITE 1 KARANGAHAKE ROCKS
Background Information
Millions of years ago, molten hot rock formed the volcanoes now known as
the Coromandel Ranges. As the rock cooled, it developed cracks and crevices.
Super hot water (230o-280oC) containing metallic minerals rose up from the
hot rock deep below the mountains. As the water cooled it deposited gold,
silver and a range of crystalline minerals including quartz, in these cracks and
crevices - forming quartz ‘veins’. It is in these ‘veins’ that gold, silver and
other minerals can be found.
Where to go
Any accessible stony patch along the Ohinemuri River will give productive
rock hounding. The best area for schools is at the confluence of the
Ohinemuri and Waitawheta Rivers (over the swing bridge and to your left).
Keep conservation in mind and ask students to borrow a small representative
collection (no more than six prized specimens) for observation and
replacement. Look out for quartz crystals, which can also be found in the
Ohinemuri and Waitewheta rivers.
What to do
1.
Collect your rock sample – choose smaller, flatter rocks.
2.
Put on the safety glasses.
3.
Wedge the rock between other rocks to stop rock fragments from
flying off.
4.
Strike the rock with the rock hammer.
5.
Use a 3-D viewer or Waltex magnifier (8x magnification), holding the
viewer close to the eye and the rock close to the end. View the rock in
sun if possible, so you can see crystals sparkling.
6.
Sketch or write down what you see.
What you can expect to see
Andesite and dacite
Karangahake rocks are mainly andesite and dacite volcanic rocks, that erupted
between 10 – 12 million years ago. They are grey with light coloured flexes
through them. When broken, many crystals are seen in the dark grey
background. The crystals, if light coloured (white or colourless) will be quartz
and feldspar. Darker crystals, probably greenish, will be chlorite or pyroxene.
Small shining specks may be pyrites.
The other rocks are the same andecites and dacites but they have been
changed by hydrothermal alteration.
Quartz
Quartz rocks are easy to identify. They are white, cream or pinkish with the
crystals easily seen. An examination with the lens will show the crystal side
shapes and pointed ends especially if holes and crevices in the rock are
examined. When broken to expose a fresh face the quartz, fledspar and
chlorite crystals will give a huge array of colours with good-sized cube crystals
of iron pyrites (fool’s gold).
24
V.
SITE 2 RIVER SURVEY
Background Information
Water pollution from mining
In 1895, the Ohinemuri River was declared a ‘sludge channel’ devoid of all life.
From 1895 to 1952 the Victoria Battery, capable of processing 200 tons of ore
per day, dumped 11 million tons of waste into the river. The waste consisted
predominantly of rock ‘flour’ as well as a wide variety of toxic chemicals. In
addition, waste was also added from the Crown, Talisman and Woodstock
Batteries.
In its heyday, all town and domestic waste was also dumped into the river,
most from specially built platforms.
A highly valued Maori food resource of freshwater fish and eels was
completely destroyed. The degradation continued unabated until mining
ceased in the 1950s.
Floods, so big that water flowed through the railway tunnel, carried the sludge
to the Waihou River at Paeroa and out to the Firth of Thames. Recent
exploration in the Firth has found gold and other minerals in the mud at
Miranda that can be traced to Karangahake.
With today's environmental protection laws such complete destruction of an
ecosystem on such a large-scale would not happen.
Improvements in water quality – the presence of trout
Water quality in both the Ohinemuri and Waitawheta Rivers has improved to
such an extent that the rainbow and brown trout fishery has become one of
the most important to Auckland recreational fishers.
In clear water
conditions, trout can be spotted all along the walkway, particularly from the
bridge over the Ohinemuri River between the Waikino railway station and the
Victoria Battery.
Rainbow trout are common and weigh about 1kg. Anglers occasionally catch
brown trout weighing up to 5kg. Trout are a ‘valued’ introduced species and
are used as indicators of good water quality.
Smaller trout feed mostly on the larvae of freshwater insects such as caddis
and mayfly, whereas the larger fish target smaller fish – probably native species
of the whitebait family.
25
Water level surveys
The Waikato Regional Council (Environment Waikato) regularly surveys
waterways to ensure water quality is maintained. For example there are
permanent rain gauges and water level recorders in the Karangahake area.
Information on accumulated rainfall and river levels can be accessed via the
internet. Visit the Environment Waikato websites given below before or after
your visit – especially if there has been a significant rainfall event.
events are
by
rapid
to lack of
the
river
During the early days of
the
Victoria
Battery
operation, five acres of
forest per day was cut to
feed the kilns used to
process the ore.
Rainfall
www.ew.govt.nz/enviroinfo/riverlevelsandrainfall/rainfallmap
This web address takes you to a map of the Waikato. Click on the yellow
circle above Waihi for the latest rainfall data for the Waitekauri Catchment
(which feeds the Ohinemuri River).
River Levels
www.ew.govt.nz/enviroinfo/riverlevelsandrainfall/riverlevelsmap
On the map of the Waikato on this page – choose the yellow circle located
between Paeroa and Waihi. This will give you the latest river level readings for
the Ohinemuri River.
The graph below shows the relationship between rainfall levels and river levels
for the Ohinemuri River, Karangahake (28 March to 4 April 2001).
Graph showing rainfall and resultant rise in river levels – Karangahake 2001
Rainfall and resultant rise in river levels - Karangahake 2001
300
River level rises in
response to rainfall.
river level
16
14
250
12
150
8
6
100
River Level (m)
10
rainfall
4
50
4 April 3:00am
3 April 6:00pm
3 April 9:00am
3 April 12:00am
2 April 3:00pm
2 April 6:00am
1 April 9:00pm
1 April 12:00pm
1 April 3:00am
0
31 March 6:00pm
31 March 9:00am
31 March 12:00am
30 March 3:00pm
30 March 6:00am
29 March 9:00pm
29 March 12:00pm
29 March 3:00am
0
28 March 9:00am
2
28 March 12:00am
Rainfall (mm)
200
28 March 6:00pm
High rainfall
exacerbated
runoff, due
forest
in
catchment.
Date / Time
26
Now you’re there – Karangahake Reserve
There is a water sampling kit suitable for schools available from Environment
Waikato, Grey Street, Hamilton, Tel: 07-856-7184. Remember to return the
kit as soon as possible after you have finished with it so that it can be used by
other schools. Record your results on the recording sheet on page 29.
What to do:
• Make sure students have a copy of the recording sheet (page 29).
Walk to the beach area downstream from the western end of the car park and
measure:
1.
water temperature,
2.
water clarity, and
3.
look for 'indicators' of good water quality.
1.
Water temperature
Use the thermometer provided in the kit. Hold the bottom of the
thermometer about 10cm below the water surface for 2 minutes. The reading
will be accurate to within two degrees. Check with another person before
recording the temperature.
2.
Water clarity
Follow the instructions in the kit for the water clarity tube and the black disk
equipment. Record both disk and tube readings.
3.
‘Indicators’ of Water Quality - River Animals
Some insects and snails are water quality indicators. Use the nets to sample
several stones, following instructions in the kit. Sort the catch out and record
animals found, using the identification chart. Make a special record of any
mayflies present as the record sheet suggests. All trout observations should be
verified by two other people.
Trout
Both rainbow and brown trout live in the river and their presence is an
indicator of good water quality. Spotting from the bank, you will not be able
to identify the species. Trout are easily spotted when the water is clear and
when there is not enough wind to ripple the surface of the water. Any of the
bridges are good spotting places as well as sections of the walkway that gives
views of smooth running water.
Trout are solitary and large (up to 50 cm long, commonly 30 cm) and cruise
slowly upstream. Other fish are smaller (except the odd eel) and may be in a
shoal. Bullies will be darting around the rocks on the bottom.
Common bully
27
Mayfly
Mayflies (Deleatidium species) are used by biologists as indicators of high
quality river water.
Use the nets to catch mayfly nymphs - by placing the net immediately downstream of a (rugby ball sized) stone. Keeping the stone underwater shake it
and wipe off any attached ‘material’, the current will carry the catch into the
net. Empty the contents into the observation tray and sort out the mayfly
using the diagram as a guide. Do this with several stones - always replace
them right side up.
Mayfly nymph
(Deleatidium species)
While keeping the rock
under the water – wipe
off any ‘material’ attached
to the rock.
Hold the net down-stream from a stone
about the size of a rugby ball.
Direction of water flow.
Catch the loose ‘material’ in your net.
Identify Deleatidium from other mayflies (all of the family have three distinct
‘tails’) by their long spiky tails, not feathered like some other species and with
the middle tail often longer than the other two. Compare their abundance
with other animals found and rate them as none, rare, few, common, very
abundant.
28
RIVER SURVEY RECORD: OHINEMURI
School: ______________________________________________________
Teacher: _____________________ Class / Year: ___________________
Date: _______________________ Time: ___________ to ___________
1
Temperature = _________________ oC
(see Environment Waikato kit)
2
Water clarity tube:
at ______________(time)
__________________________
metres
Black disc:
__________________________
(see Environment Waikato kit)
metres
3
Number of trout spotted: _________________________________
(see Environment Waikato kit)
4
Sightings of fish other than trout. A nil result is important to note.
Comments about these: (see notes in this kit)
______________________________________________________
______________________________________________________
5
Abundance of mayfly nymphs:
(see notes in this kit)
T none
T rare
T few
T common
T v. abundant
Notes: ________________________________________________
6
Rainfall in the Waitekauri Catchment over the last 24 hours
(mm). (see notes in this kit).
______________________________________________________
7
River levels at time of visit: ____________________ m
Metres rise/fall in last 24 hours: ________________ m
(look this up on the Environment Waikato website)
29
VI. SITE 3 GOLD MINING AND GOLD
FROM QUARTZ EXTRACTION
The rocks inside Karangahake Mountain and the gorge area are extremely
hard. Miners would find a ‘vein’ of quartz rock that was likely to contain gold
by exploring the exposed rock faces on the mountain. A ‘vein’ is an
accumulation of minerals, usually in quartz, and may range from 5 to 30 cm
across.
They would tunnel into the rock following the vein to create a mine. Because
the rock was so hard they had to drill long holes into the ‘face’, into which
they placed explosives. The force of the ‘shot’ would shatter the rock so they
could use picks and shovels to load rubble onto rail trolleys for transport to
the surface.
The miners would know how much explosives to use so as not to harm the
rest of the mine. Once the ‘ore’ (gold bearing quartz rock) was on the surface
it was transported by horse drawn trolleys along tram rails (or in the case of
the Talisman Mine, aerial tram) to the battery for processing.
The entire area
shown in this
diagram is
termed the ‘lode’.
The horizontal tunnels are also
called drives or adits. They were
usually dug on a slight angle to aid
drainage and transport of ore.
Diagram showing extent of underground mine tunnels in Mount
Karangahake - Karangahake Goldfield in 1913.
Trig Station
stopes
Shafts were dug vertically (or
on a slight angle) into the
rock:
Diagram: S. Frimmel
Over the many years
the Karangahake
goldfield was worked,
up to 1000 tons of ore
was mined and
processed daily.
This cross section gives an idea of the extent of the mining undertaken on Mt
Karangahake. This is a two dimensional view, imagine a three dimensional
model of the same view showing the mine shafts and tunnels.
The dark areas show the actual amount of quartz bearing ore removed for
processing. These areas are called ‘stopes’.
30
Processes involved in recovering gold from ore.
Reproduced with permission from: Moore, P. and Ritchie, N. 1996. Coromandel Gold: A
Guide to the Historic Goldfields of Coromandel Peninsula. Dunmore Press, Palmerston
North.
Back at School and While You’re There
What to do
1.
Use the information from the above diagrams and from the signs and
display panels to write a description of the processes used to recover gold
from ore before and after the introduction of the cyanide process.
Information from the Crown Battery will be a source for setting out a clear
(mostly in your own words) step by step order from crushing to bullion, but a
visit to the Victoria Battery Tramway Society’s facility will be the best
information source.
2.
Learn the meanings of these words: quartz, cyanide, bullion, smelting,
precipitation, miner’s phthisis, zinc.
3.
Why was the cyanide treatment process such an important discovery
for the Karangahake gold fields?
Restrict your work to the early days of mining in Karangahake and Waikino.
However, keep in mind later developments that made the work of extraction
more efficient right up until mining activity ceased in the area in 1952.
31
Now you’re there – Karangahake Reserve
What to do
From the car park at the Karangahake Reserve, cross over the swing bridge
(take note it only takes a maximum of 10 people at a time). Over the bridge
there will be a track to your left and a little further a track to the right – go
straight ahead. A 10 minute walk up the ‘true’ left bank of the Waitawheta
River (river banks are named looking down stream) leads to another swing
bridge. Go past the bridge and carry on through the short tunnel and look for
the quartz vein about 20 metres beyond in the face of the cliff. This vein is
the kind of sign that miner's would look for before starting a drive or a mineshaft.
Some of the mine drives that can be seen on the track and the tunnel show
how hard the rock was to mine. The explosion from a dynamite charge
packed into holes bored into the rock, loosened it and large crowbars and
picks were use to break it out of the working face. It really was ‘hard rock’
mining!
VII. HISTORIC STRUCTURES AND
BUILDINGS
Now you’re there – Karangahake Reserve
What to do
Stand by any of the display signs with photographs of the gorge when mining
was in operation (such as the ones located near the Karangahake Reserve car
park). Some photos show the batteries and others the townships. Look at
the photos given on pages 34 - 41 in this kit and refer to the map on page 33 showing the location of the old Karangahake township, the Crown Battery
site, Woodstock Battery site and location of pumphouse, and Talisman Battery
site.
1.
Use the photos and the actual scene before you, to visualise the actual
setting as it was in the early 1900s. Describe this to a friend pointing
out where things were and let them extend your description or
describe other areas.
2.
Describe what the sounds would be like, from the batteries, the
township and the railway and discuss the differences to the sounds
you can hear now.
3.
As you investigate the remains of the previously thriving industry and
township, list what structures have survived and what have not. Give
reasons for this.
4.
How can we make sure that what is left remains for future generations
to discover and enjoy. Make a list of things to be done to ensure this.
Research how iron materials are preserved, engineers will know.
32
5.
One activity that archaeologists working in places like Karangahake and Waikino do, is make detailed drawings of what they see.
could possibly keep to show your own children.
Make your own that you
6.
Choose one of the structures you could draw in detail during 1 hour using pencil or crayon on newsprint. A cardboard or clipboard backing support will
help. It is important you sign and date your work.
The photos on pages 34 to 41 show pictures of the Karangahake township, the
Crown Battery, Woodstock Mine buildings, Woodstock Mine Pumphouse, the
old tramline, and workers outside the No.8 Level portal of the Talisman Mine
(see diagram on page 30).
N
2
Victoria 2
Battery
Site
The Crown Battery
Ohinemuri River
Railway Tunnel
(walkway goes through here)
T
Waikino
Visitor
Centre
Owharoa Falls
2
P
Karangahake Walkway
Karangahake
Reserve
car park
The Woodstock
Mine ‘Pumphouse’
Woodstock Battery
Talisman Battery
Site of old Karangahake
township
Pukekauri Road
Road
Walking Track
Stream
Waitawheta River
Waitawheta Road
0
0.5
T Toilets
P Parking
1km
33