1. New Zealand Volcanos
What are Volcanos?
Volcanos are found all over New Zealand. Volcanos are large hills or flat
ground that are made when either two techtonic plates colide or if
there's a weak spot or hot spot in the crust. New Zealand volcanos are
made by the both of these reasons, they have also formed lakes or basins
such as Lake Taupo.
How a Volcano Works?
To form a Volcano a Subduction Zone happens. A Subduction Zone is
when a techtonic plate colides with another or meets with another, which
rattles the earth above. As the techtonic plates moves the ocean crust
heats up forcing into the mantle. Then hot, boiling magma is produced, it
is produced by high pressure and high heat rising higher, once the
magma reaches the vent it turns to lava. The lava explodes and forms a
volcano! New Zealand volcanos used this same process but in some
cases such as Rangitoto, the techtonic plates didn’t move, instead there
was a hot spot in the crust!
What do Volcanos look like?
Volcanoes shape and size depends on the explosion style, some may be
lava flows and lava fields, some fire fountains and some explosive
eruption. All of these explosion styles create a different shape and size.
Lava flows and lava fields form a shield volcano which is a large long hill.
It is usually formed by large lava flows!
New Zealand Volcanos
There are over sixty volcanoes, basins and lakes in New Zealand. All these
volcanos are different some big, some small, some coned shaped, some
shields, there is even a lake. Auckland and Taupo have the largest volcanic
fields in New Zealand, they are either active, dormant or extinct. When a
Volcano is active it is still working, it means that there still could be
another eruption from an active volcano. A dormant volcano is a volcano
that rarely erupts currently but may have erupted long ago in historic
times. An extinct volcano is an volcano that scientists think that are
unlikely to erupt again.
Auckland Volcanic Field
Auckland volcanoes are different to other volcanos in New Zealand. They
form not when techtonic plates colide but when there is a hotspot or
mantle plumes in one of the techtonic plates, once the hotspot appears it

2. could take days for the volcano to actually rise and start the subduction
zone process. Auckland volcanic field is made up of all Monogenetic
volcanoes, a Monogenetic volcano is a volcanic field of small, scattered
vents. The volcanoes have many monogenetic volcanoes inside the vent
which erupts several times from that same vent over a long period of
time. The small, scattered volcanoes are formed from magma bubbles,
every magma bubble will produce another small volcano inside the vent.
Thats why in Auckland there are so many volcanoes.
Rangitoto Volcano
Rangitoto Island is one of New Zealand’s largest volcanoes. The large
eruption started with underwater eruptions building up, then a scoria
cone formed by a fire fountain, later lava filled up and overflowed the
crater and lava spread on the sides creating a shield volcano. Rangitoto’s
explosion was so large it erupted more volcanic material than all the
other Auckland volcanoes put together, it erupted 2,300 million cubic
meters of lava which would fill 468,000 Olympic sized swimming pools
and left 19 million cubic meters of tuff, ash and pyroclastics which would
fill 3,800 Olympic sized swimming pools. Rangitoto Island has a distinct
look, there is a scoria cone and two scoria mounds on the top of the
volcano, also it looks like it has two peaks which it doesn’t. The scoria
cone is so distinctive because the mounds on the scoria cones are from
earlier eruptions and there is a deep crater in the scoria cone. The
surface of Rangitoto is very rough, it is rough because the top layer of
lava hardened but the lava underneath kept moving. Caves were made
when the hot lava drained out which are still visible today.
Rangitoto History
Rangitoto is a big part of Maori history, a lot of people lived on Motutapu
Island before and after the eruption occurred. The name Rangitoto was
shortened from Te Rangi-i-totonga-a-Tama-te-kapua which meant ‘Blood
of Tama-te-Kapua was shed’. He was a chief of Te Arawa canoe, he had
to fight in hotorua, and he lost his life.
Since the eruption Rangitoto and Motutapu Island have come together as
one, it was used for burial, look out in case of war, fishing camps, parrot
reserve and housing. On Rangitoto Island there are many baches as
Rangitoto came a public domain in 1890, people visited for day trips and
picnics. Also money was raised by renting out places on camp sites,
campers would build sheds to store there gear in. Overtime some
changes were made sheds were added to, sheds became holiday baches
and now over 100 privately owned holiday baches are there. Even in the

3. 1920s to 1930s prison labour was introduced to the Island, prisoners we
forced to build roads, a swimming pool, a changing shed, a community
hall, a tennis court and even a jetty.
Plant Life
There are a lot of different plants growing on Rangitoto now, there use
to be no plants growing as it was hard to find soil and water beneath the
hardened lava rocks. Many hundreds of years after the eruption,
pohutukawa trees started growing beneath cracks in the lava rock, then
other plants grew under the pohutukawa. The pohutukawa trees on
Rangitoto are over 200 years old, from then the volcano has grown many
more plants. It has 228 species of native trees and flowering plants, 94
species of mosses, 67 species of liverworts, 54 kinds of fern and 21
species of orchid. On Rangitoto there are many unusual plants growing
such as the pohutukawa and rata have bred together, epiphytes are found
growing on the ground which usually grows on other plants, mangroves
have been growing on lava, but they usually grow on salty mud flats and
the alpine moss is growing by the sea it usually grows on top of
mountains.
Wild Life
Rangitoto is full of wildlife, it is a home to many native and forest birds.
Moreporks, Fantails, Grey Warblers, Silvereyes and are all forest birds,
there are not many forest birds because in Rangitotos condition there
isn't much food for the forest birds to eat. The Moreporks and Fantails
are just some of the native birds living on the island, now that all pests
have been removed from the island it makes it easier for them to
survive. That's why when you come to the island you have to check your
boats, shoes and bags for insects and pests to be most careful, also there
is a strict no pets policy which is obeyed. Rangitoto community and
conservations hope that Rangitoto will be become a wildlife sanctuary to
protect the endangered and native wildlife that live on the island.
Conclusion
Rangitoto is a historic shield volcano that erupted over 600 years ago, it
has two scoria cones and was formed by a hotspot in a techtonic plate.
Over the years plants and trees have grown and the wildlife population
has rose as it is going to try and become an animal sanctuary for
endangered and native wildlife. Rangitoto is important to Auckland and
always will be!