AS 91189 Investigate geological processes in a New Zealand locality.

AS 91189 Investigate geological processes in a New Zealand locality.

AS 91189 Investigate geological processes in a New Zealand locality.

AS 91189 Investigate geological processes in a New Zealand.


132,000 years of violent volcanic activity then they built Ash Pit Road (Prezi).

Tephra deposited from multiple eruptions in the Taupo volcanic Zone.The history of the area is written in layers of ash revealed in a cutting on Ash Pit road close to Rerewhakaaitu. 

The land and Lakes Field trip document is a good resource and you should flick through it and highlight sections that deal with basalt, rhyollite, the Taupo and Tarawera eruptions. You will come across a section on the road cutting on Ash Pit road.


Skim read to begin with and don’t get bogged down in detail

The Tarawera eruption.

This is a useful resource on the Tarawera eruption

The Okataina Volcanic Complex

GNS Science, TE PU AO iis a government website with lots of Earth and Geoscience resources

The Okataina Volcanic Complex

The Okataina Volcanic Centre is part of The Taupo Volcanic Zone ( TVZ ).

 Plinian eruptions send huge volumes of ash into the stratosphere and this can have global implications. Individual ash deposits show a fine grained layer at the top indicating that the eruption faded after the initial explosive event

The Okataina Centre includes the large young volcanoes of Tarawera and Haroharo, with others at Mt Edgecumbe, Okareka and Rotoma


New Zealand volcanoes such as Ngauruhoe and White Island, have relatively small eruptions every few months or years.

Eruptions in the Okataina volcanic complex, are 100 to 10,000 times larger than those at White Island or Ngauruhoe. 

Okataina Complex volcanos  have displayed eruption intervals between 700 and 3000 years.

There have been 12 devastating Plinian eruptions in the period between 31 and ∼43 ka. The pyroclastic deposits total 77 km3. The biggest eruptions in the region were extremely destructive burying areas of up to 4,200 km2 to at least a depth of 1 meter.

The Auckland Region covers an area of 4894 km2 . 



The Kaharoa eruption and The Great Famine of 1315-1317



The onset of the Great Famine coincided with the end of the Medieval Warm Period. Between 1310 and 1330, northern Europe saw some of the worst and most sustained periods of bad weather in the entire Middle Ages, characterized by severe winters and rainy and cold summers. The Great Famine may have been precipitated by a volcanic event,[3] perhaps that of Mount Tarawera, New Zealand, which lasted about five years. (Wikipedia)

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Nga Tapuwai o Mataoho, footprints of Mataoho. Mangere Mountain

Mangere Mountain has a number of important features for Auckland Volcanic Field geeks to get excited about.

  • the shape of the scoria cone (steep sided compared with Rangitoto a shield volcano where the molten basalt flowed freely without a high gas content.)
  • major landsape features and processes (explosion crater, large southern cone with a smaller cone to the north)
    Other landscape features including a breach on the eastern side of the southern cone that allowed basalt to flow freely where the football fields are now. Another minor breach that local Maori had to fortify to prevent incursions by unwelcome guests
  • Assorted lava bombs and evidence of fire fountaining as volcanic activity waned
  • Human impact through stone gardens, kumara pits. There was substantial quarying as durable basalt and scoria were removed for building purposes.


The mountain is still there but the Greenbay High School students who went on this trip have now moved onwards upwards and sideways

Mangere Mountain field trip 2011 from john west on Vimeo.

Pupuke an early eruption in the Auckland volcanic field looking towards the youngest, Rangitoto.

Study revision: The Auckland Volcanic field

  • Look at the presentation on the Pupuke eruption in the Auckland volcanic field. It’s a good example of the stages that eruptions generally follow (explosion crater, scoria cones, lava fields). Take time to do this properly. There is no easy shortcut to success at level 2.
  • Ask for help when it doesn’t make sense.
  • Tackle the question on the formation of pupuke ( a large explosion crater, small scoria cones buried under lava flows, lava field that flowed through an ancient forests.
  • Don’t sweat the small stuff, ask for assistance early

How do I answer the Question?

Don’t sweat lots of small stuff. Use NCEA assessment schedules to find what examiners are looking for. The list below consists of phrases and ideas from an an NCEA assessment schedule used with a similar question about the Auckland volcanic field.

Develop  these phrases and ideas into paragraphs. This should at the very least ensure get “achieved” in any question on the Auckland volcanic field. Finally make sure you have a sentence explaing each of the labels on the stylised scoria cone in the presentation.

Adapted from ESS Extreme Events 2012

  • Lake Pupuke formed when the hot basalt came in contact with the cold sea water or wet sedimentary deposits
  • the eruption became very violent forming steam
  • Material blasted out of the volcano upwards and outwards
  • Formation of a tuff ring and a large explosion crater
  • Scoria cones, steep sided. Lumps of hot lava thrown upwards and outwards from volcano in a molten state.
  • Scoria. Gasses trapped in the magma drive the eruption. Fire fountaining.
  • Steep sided scoria cones built up.


Where does the magma come from, lava flows?

  • Hot spots where magma from the mantle rises towards the surface.
  • Basaltic lava forces its way through the overlying crust
  • There is no magma chamber
  • Melted magma has come from great depths
  • Same chemical composition as the mantle.
  • Basalt has low viscosity
  • Low silica content. Silica lends the viscosity component hence basalt has low viscosity
  • Lava flows out over the edge of the tuff ring.


General sequence for Auckland volcanoes

  • Phreatomagmatic explosion
  • Large explosion crater
  • Tuff ring
  • Lava fields as low viscosity basalt pumped up through a vent over the tuff ring


After you have looked at the presentation try the question on the formation of Lake Pupuke.

Rate of Reaction including particle size and catalysts

Homework due Thursday April 7

Read the complete presentation on Rates of Reaction. (concentration, temperature, catalysts and particle size) I strongly advise that you take time to watch the videos on the effects of concentration, temperature and catalysts on the rate of reaction. It is important to have a mental picture of how these investigations are carried out. The video on the effect of catalysts was made by students.

Do the homework worksheet after the presentation



Writing fully balanced chemical equations

Writing fully balanced chemical equations

Look at the presentation then complete the worksheet on fully balanced chemical equations. It is due Thursday next week. See me today at lunch or Wednesday lunch next week for help if you are having difficulties. Use your text book as well.

Previous posts on this achievement standard:

February 26 2016: Atoms, Ions and ionic compounds, how to answer questions on this part of the standard. AS90944

March 1 2016 :Acids and Bases AS90944

March 20 2016: The factors affecting rates of chemical reactions







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