South Island High Country Land modifying processes: Glaciation Fluvial erosion Freeze – Thaw action Wind Erosion Mass movement

Land Building Processes Land Modifying Processes Cycle of Landforming Land Building Processes Folding Faulting Volcanism Land Modifying Processes Erosion Weathering Transportation Deposition Causes of erosion Glaciers Rivers Wind Freezing and Thawing

Weathering Copy/summarise the definition for weathering from the Geography on the Edge textbook from page 25. Write 1 sentence to explain expansion and contraction.

Different types of erosion in our environment Fluvial Caused by the action of rivers/water – Mainly where? Glacial Caused by the action glaciers – Mainly where? Freeze-Thaw Caused by the freezing and melting of water in rocks. As water freezes and can cause rocks to shatter. Mainly where? Aeolian Caused by the movement of wind – Mainly where?

Due to high altitudes (and cool temps) Glaciation is an important land-modifying process. Some glacial features that can be seen throughout the High Country are: U-shaped valleys – which form as glaciers advance down the valley. e.g. Deep Finger Lakes - which are in old glacial valleys. e.g. Cirques – bowl/arm chair shaped basins where glaciers begin. e.g Horn Peaks – e.g.

Arête Using the information on page 29 draw a quick (5 min) annotated diagram of how an arête forms. Make sure you give an example from the SAs.

Many of these features were formed during ice ages, the last ice age started about 2 million years ago and ended approx. 10,000 YA. During this time most of the South Island was covered in ice. The glaciers formed in Cirques (hollows at the heads of valleys) and grew larger and heavier, they then travelled down the valleys, eroding the sides and floors of the valley as they travelled.

Helpful diagram to explain present and past glaciation processes Go to page 28 in Geography on the Edge text and combine the During and After Glaciation diagrams to show what’s happening in our region. Make it specific to the SA/EHC HINT – the valley on the left is The Hooker and the valley on the Right is The Tasman If you want to get the scale more correct use the Topo map from page 7 to help.

Medial Lateral Terminal moraine Often when the glacier retreats the terminal moraine at the former nose of the glacier dams the water and forms a finger lake in the U-shaped valley behind

Freeze-thaw The intense cold of the High Country (esp at night) means the peri-glacial process of freezing and thawing is very active. Erosion from freeze-thaw occurs when water seeps into a crack in a rock, at night the freezing of this water causes it to expand as it turns to ice – causing the crack to widen. When thawed water seeps further into the crack – freezes – widens – thaws – seeps This causes rocks to break up, resulting in giant shingle slides which can be 100s of metres high. These are called scree or talus slopes.

Copy the freeze-thaw diagram below

Now add some specific evidence from the following information to your diagram. http://www.slideshare.net/cheergalsal/freeze-thaw-weathering-solution-weathering Finally… http://subscription.echalk.co.uk/Geography/ice/glacialErosion/glacialErosion.html

What particular feature (relief characteristic) does freeze-thaw create? Can you name/locate one in the Eastern High Country?

This can be caused by a number of factors: Steep slopes Mass movement is the slipping of rock and soil down a slope either as rockfalls or landslides or slips. This can be caused by a number of factors: Steep slopes A weak geological structure Earthquakes Prolonged periods of rain – lubricating the soil. 24th Dec 1991 Mount Cook 10m

Read bullet point 2 on page 10. Write one sentence to explain the mass movement process which changed Aoraki in 1991.Include specific evidence. https://www.youtube.com/watch?v=oSAmOhqvVZQ But that’s not all…. http://www.3news.co.nz/environmentsci/video-aoraki-mt-cooks-biggest-landslide-in-20-years-2013012816#axzz3jxmzzkcl

Aeolian (wind) erosion Important where there are strong prevailing winds e.g. in the relatively dry Eastern High Country. Fine particles of dust or unconsolidated soil, loosened by rock-slides, sheep etc are blown down slope towards the east. Some parts on the edges of the Eastern High Country and further East (Canterbury Plains) have been covered in fine grit and dust called Loess, which is blown down by the föhn winds (hot, strong, dry northeast wind that blows down from the Southern Alps). This process is not as active as other erosional forces.

Copy the diagram below - give it a title and any specific evidence you can. Fohn Wind blows unconsolidated soil Zone of wind erosion Canterbury plains Zone of loess deposition South Island High Country

Skills break Use the following slide to create three percentage bar graphs. Apply appropriate conventions.

New Zealand’s Landform Patterns % Mountains % Rough Hill Country % Rolling Hill Country % Plateau % Plains New Zealand 49 25 15 3 8 North Island 18 45 26 6 5 South Island 70 12 9

Glaciers/glaciation processes http://subscription.echalk.co.uk/Geography/ice/glacialErosion/glacialErosion.html Cirques http://subscription.echalk.co.uk/Geography/ice/corrieFormation/corrieFormation.html

Theory of glaciers…. Glaciation full length DOC powerpoint. Watch https://www.youtube.com/watch?v=SROTOaENeHs https://www.youtube.com/watch?v=IScnw7nt2Sw

https://www.youtube.com/watch?v=mspVqx3vgek