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Students are mapping out the routes of the early explorers, sealers and

surveyors of Doubtful Sound and Lake Manapouri. Their legacy is

everywhere - in the names of coves, mountain peaks, rivers and

fiords, fascinating survey pegs of history on a topographic map.

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While the Cook and Malaspina expeditions with their wind dependent

sailing ships didn't go very far into the Doubtful Sound, in case there was

no wind to blow them out again, the steamship Acheron could travel more

freely as the pinned out flags show.

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Turning a 3D mountain into a 2D map - decoding contours...

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Slicing up a mountain to turn it into contour code...

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Recreating the last Ice Age by reading contour clues...

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Cirques, arétes, pyramidal peaks and horns, truncated spurs and hanging

valleys, U- and V-shaped valleys, tarns, moraines and more...

Survey Pegs and Doubtful Ghosts

The senior students are preparing for a camp in Doubtful Sound. The South West coast of New Zealand is remote, wild and mountainous and lies directly in the pathway of the Roaring 40's westerly air stream.

These prevailing westerly winds presented a problem for early explorers in their sailing ships. Once blown inside the mountainous fiords they were very "doubtful" they could get back out again. They needed a wind

to blow from the east to catch their sails. Even with an easterly wing, the narrow fiords lay thousands of metres below the mountain tops, completely sheltered from the wind by the giant mountain walls.

Doubtful Sound is full of place names linked to the first explorers. By matching each place name to the explorer who gave it, students discovered that place names are like survey pegs of the past and set in stone

(or bays or islands) permanent reminders of ships, their crews, their home towns, family members and important people in their countries at the time.

Students also discovered that names were often chosen to describe topographical features, useful to other mariners before areas were properly surveyed and maps were imprecise.

Doubtful Sound Explorers:

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britain flag cook
Spanish ensign
seals
acheron

Captain James Cook

British Explorer

Ship: Endeavour

1770

Alessandro Malaspina

Spanish Explorer

Ship: Descubierta and Atrevida

1793

Captain John Grono

Australian Sealer

Ship: Governor Bligh

1809

John Lort Stokes

Surveyor - Hydrographer

Ship: Acheron

1851

Spanish Translation Challenge: Translate Malaspina's map and an interesting extract from his Expedition Journal...

It's not as difficult as it looks. The English and Spanish languages have Latin roots and words look very similar...

" La expedición Malaspina tuvo por misión realizar una serie de experimentos....."

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marcaciones point plaque

A plaque marks Marcaciones Point which is the exact spot where the first European,

Don Felipe Bauza landed in Doubtful Sound on 26th February 1793. He took observations

from Marcaciones Point. ‘Marcaciones’ is Spanish for markings. Bauza was a cartographer,

a member of the only Spanish expedition to New Zealand.

The Perfect School Camp - An Ancient Landscape Carved by Ice, Shaken by Earthquakes, Battered by Wind and Drowned by Rain...

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Doubtful Sound or Doubtful Fiord?

Fiordland’s West Coast is deeply indented by 14 fiords spanning 215km of coastline.

Its steep, spectacular mountains rise up almost immediately from the ocean.

Early European explorers gave the names of Sounds to these dramatic valleys, however

a true ‘sound’ is a river valley that has been flooded due to the land sinking below sea level.

Fiords are created by glacial action that produces U-shaped valleys with steep cliffs.

Fiords are also characterised by shallow entrances that slope quickly seaward to deep water.

So Doubtful Fiord is more accurate.


tectonic plates

Beneath New Zealand two pieces of the Earth’s crust are in collision.

The Indo-Australian plate is being driven alongside and under the Pacific plate,

creating the Fiordland Massif (group of mountains). The two plates crash into each

other forcing rocks upwards which form the Southern Alps.

Ancient rock layers have been mangled and shattered, and rocks formed millions of

years apart are now jumbled together.


The mountains of Fiordland are made from some of the hardest, oldest rocks in

New Zealand. These rocks formed on an ancient seabed some 400 million years ago,

long before the islands of New Zealand existed.


Originally deposited as rock sediments washed off the edge of the ancient landmass of

Gondwanaland, the original chemistry of these sediments was altered under huge

pressure, morphing into the interesting metamorphic rocks you pick up in Deep Cove

today.


rainfall ans southern alps

Doubtful Weather - A very wet mix of wind, sea and land.


In Fiordland an average of about 7 metres of rain falls per year, over an average of

200 rain-days per year.

This huge rainfall is due the ‘Roaring Forties’ westerly air streams.

The strong west-to-east air currents are caused by the combination of air being

displaced from the Equator towards the South Pole and the Earth's rotation.

There are few landmasses to serve as windbreaks.

These westerly winds pick up moisture as they cross the Tasman Sea and

are pushed up against the mountains. The rising air cools.

The water vapour in the air, evaporated by the wind from the Tasman Sea,

condenses and falls as heavy rain and snow at high levels.

The condensation process releases heat and the descending air warms

and results in the dry, warm nor'westers which blow across the Canterbury

Plains.



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A Westerly air stream hits Doubtful Sound

As the clouds are pushed up higher by the mountain peaks,

water vapour condenses and falls as sheeting rain


"It rained and rained and rained and rained,

The average fall was well maintained,

And when the tracks were simply bogs

It started raining cats and dogs.

After a drought of half an hour

we had a most refreshing shower,

then the most curious thing of all:

a gentle rain began to fall.

Next day was also fairly dry

save for the deluge from the sky

which wet the party to the skin:

and after that, the rain set in."

- Anon

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A Landscape formed by Ice and Snow

The landscape of Fiordland was created during the last ice age, between 75,000

and 15,000 years ago . Glaciers scoured the landscape to create the coastal fiords

and inland lakes.

During the last ice age in Fiordland, huge amounts of snow accumulated in the

mountains. The snow was compressed under newer snow until it melted and refroze

melted and refroze to form glacial ice.

At the base of these glaciers, ice melted under pressure and the whole mass

began to move.

Ice itself cannot cut or erode rock - rocks imbedded in the glacier did the carving

and caused the erosion, reshaping shallower V-shaped valleys worn by rivers into

the dramatic U-shaped valleys we see in Doubtful Sound today.


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5,000 years ago the Ice Age ended and the glaciers melted leaving behind a very

interesting landscape. The mountains at the edge of the glacier's path have been

ground away leaving steep truncated spurs which drop 400metres down to the bottom

of Doubtful Sound. Waterfalls cascade over the edge of almost perpendicular rocks in

hanging valleys fed by lakes of rain and melted snow.

The lakes are found in hollows made by ancient cirques. The cirques mark the top

of the glacier where the mass of snow and ice accumulates before it begins to flow.

From the Wilmot Pass Road, as you look down to Doubtful Sound on a clear day

you can spot horns, arêtes, hanging valleys and former glacier troughs.


u-shape valley

Landscape clues to a frozen past...

A U-shaped valley in Doubtful Sound formed by a tributary glacier.

Glaciers can erode rock from the sides of a valley as quickly as they erode rock

from the floor of the valley. This gives glacial valleys their U shape.

Streams create V shaped valleys because they are constantly seeking base level

and erode more rapidly on the valley floor than sediment can be eroded from the

valley walls.The steeper the river falls, the more quickly it cuts through the valley

floor and the more sharply angled the V shape.


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Here, the wall of the main fiord meets a valley carved by a much smaller tributary

glacier.

During the Ice Ages the main Doubtful Sound glacier shaved off the smaller one

leaving a clear U shaped valley high on the mountainside. Now the ice has retreated,

melting snow and rain form a stream which now pours over the edge of the truncated

valley. These waterfalls are called Hanging Valleys. You can see them all along the

mountain peaks lining Doubtful Sound.


Understanding Topographic Maps




Topographic maps allow you to see a 3D landscape on a 2D surface - a flat map.

Topography means the shape of the land's surface.

These maps show the land's contours (curves) elevations, (heights) mountains,

valleys, bodies of water, vegetation and more.

Co­ntour li­nes are the greatest distinguishing feature of a topographic map.

Contour lines follow lines in the landscape that are the same elevation.

How to read contour lines
contour lines

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Finding Ice Age Clues on a Topographic Map





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Source: http://www.bbc.co.uk

Glacial troughs, spurs, cirques, arêtes and hanging valleys on a topographic map.


freshwater layer

brachiopods

Brachiopods
Source: http://www.ianskipworth.com

Beneath the Reflections

New Zealand’s fiords are like no other marine environment in the world.

Doubtful Sound's very heavy rainfall results in a permanent layer of fresh water sitting

on top of the denser salt water. This freshwater is stained brown by harmless plant

chemicals called tannins, washed out of the vegetation on the forest floor which cut

down the amount of sunlight that penetrates the water.

This darkened environment restricts almost all marine life to the top 40 metres of water.

Species normally found in deep water can be found just 5 metres below the surface.

The fiords support the world’s biggest population of black coral trees some of them up to

200 years old. In other parts of the world, Black Coral is found at 75m - beyond a diver's

range.There are also brachiopods, a primitive clam-like animal which have remained

unchanged for over 300 million years.



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Brittle Snake Star on Black Coral (it's the dead coral's skeleton that is black)Source: http://www.ianskipworth.com


Click HERE for a gallery of underwater species found in the 40 metre band.

Experiment: The Freshwater Layer

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Step 1: Make the sea water and the freshwater layer.

Sea water: Dissolve heaps of salt to some warm water - your

aim is to make a super-saturated solution.

Freshwater layer: Make a quantity of very strong tea.

Step 2: The jar is the fjord, the salty water is the sea and the

tea is the rainwater stained with leaf tannins.

Gently pour the rainwater into the sea down the side of the

fjord. The less dense rainwater with settle in a layer on the

denser salty sea water.

Step 3: The torch is the sunlight.

There has been heavy rain and

water has poured over the forest

floor, down the mountain side an

into the fjord. Shine your torch to

see how the tannins in the freshwater

filter out the light.

The arrows mark the colour of the light passing through the

water. On the left the light beam passsing through the salt

water is bright without the tannin stained freshwater above.

On the right the light beam becomes darker as it passes

through the tannins. Any bottom dwelling animals are

tricked into thinking they are lower down in the fjord than

they actually are and make their homes closer to the surface.

Manapouri Power Station


Hydroelectric Power is made from the energy of falling water...

Lake Manapouri is 179 metres higher than Doubtful Sound on the West Coast.

It is this difference in height that makes Manapouri a perfect site for generating hydroelectric power.

  • The water, falling through a pipe called a ‘penstock’, is used to spin a turbine.

  • These turbines look like large wheels with wide spokes.

  • The water hits the blades and pushes them to make the turbine spin.

  • The spinning turbine spins the generator, which generates the electricity.

  • This spinning therefore ‘changes’ the force of falling water into electricity.

It's not possible to store large amounts of electricity. But it is possible to store water in dams or lakes.


The water is stored in Lakes Te Anau and Manapouri which are joined by the Waiau River.

The amount of water flowing down the river is controlled by gates.

When the water level on Lake Manapouri gets too low, the gates are opened to allow water from

Te Anau to flow down the river.

When the water level on Lake Manapouri is too high, the gates are closed and the water drains out

of Manapouri by opening another set of gates at the end of the lower Waiau River.

The water has to be controlled carefully to avoid drowning or drying out the shoreline around

Lake Manapouri which would damage the forests and plants along the lake's edge.