Akoranga 11 Mahi Tuatahi ^🔗

1. Collect a terms/definitions match-up from the front
2. Cut up the terms/definitions
3. Glue them into your book in the correct order
4. Put all un-crumpled excess paper in the recycling bin

Te Whāinga Ako ^🔗

1. Dome, caldera, cone and shield volcanoes - what each looks like, linked to an example and the type of magma it has.

Head up a new page with the date and te whāinga ako.

Volcanoes in New Zealand ^🔗

• The type of volcano which forms depends on the magma type
• The viscosity of the magma largely dictates the shape of the volcano

^🔗

• There are four main types of volcanoes in New Zealand:
  • Shield volcanoes
  • Caldera volcanoes
  • Lava dome volcanoes
  • Composite cones (stratovolcanos)

Shield Volcanoes (Basalt) ^🔗

• The flattish gently sloping shield volcanoes of Dunedin and Christchurch are built from basalt
• The Dunedin volcano was active 10-13MYA, and the Lyttelton/Akaroa volcanoes 5.8-13MYA
• They form because low viscosity lava can flow a great distance before solidifying into solid rock

• Built of silica-poor basalt magma
• Magma comes from the mantle, about 100km deep - the hot spot. But they can also be formed by subduction sometimes.
• The magma has very little water or dissolved gas, so eruptions are very gentle.
• Eruptions are also gentle because the magma is runny and very hot, therefore it travels a long way before cooling. Therefore the volcanoes build up with very gentle slopes.

Caldera and Dome Volcanoes ^🔗

• Formed from viscous rhyolitic magma which is very viscous because it has a high amount of silica.
• Gas, especially water vapour and carbon dioxide from melted carbonates, gets trapped in the sticky lava which results in very explosive eruptions forming calderas.
• Sometimes the gas escapes so that the magma is still very sticky without trapped gas. This forms dome volcanoes.

Calera Volcanoes (Rhyolite) ^🔗

• Some volcanoes are very wide flat areas which completely collapsed following huge eruptions to form calderas (e.g. Lake Taupō).
• The eruption would have been extremely large and violent.
• Taupō last erupted about 186AD.

Dome Volcanoes ^🔗

• Mt Tarawera also formed through sticky magma being pushed upwards very slowly.
• This upward pressure is due to gas.

Cone Volcanoes (Andesite) ^🔗

• Steep cone volcanoes like Mt Taranake and Mt Ruapehu are formed when alternating layers of slightly sticky andesite lava and ash build up a cone around the vent.

• Typically formed at subduction zones
• Made up of andesitic lava which has an intermediate amount of silica
• The lava is semi-sticky and cooler. This means that it is not so runny and that it cools more quickly.
• The combination of these two factors means that it does not travel as far and forms cone shapes.
• Eruptions can be gentle, erupting lava, or explosive, eruption hot ash.

Rangahau/Research ^🔗

1. Cut out each of the images of the NZ volcanoes. Glue into your book and label - 2 per page
2. Next to/underneath your images, write:

• A description of the general shape of this volcano
• How it forms
• The magma type
• The typical products of the eruptions this volcano has
• Any special features this type of volcano has
• Other examples in NZ

NB: Use your device + textbook pages to help