Geography- large natural environment Flashcards
Where is the SIHC?
SI of NZ is characterised by steep slopes (over 28 degrees) and high altitude (land above a certain numebr)
What’s the size of the SIHC?
Rectangular shaped region approximately 500km long, which covers approximately 70% of the South Island. It covers 7 regions, Western high country, The southern alps, the eastern high country, Fiordland, The kaikoura ranges, central Otago and North West Nelson.
The story of Ranginui and Papatuanuku
According to the Maori legend, Ranginui and papatuanuku (earth mother and sky father) were forced apart from each other by tanemahuta (as he was frustrated from living in the darkness and wanted light in his life- he tore them apart) This separation gave space for new kinds of life.
The origin of NZ (Aotearoa) - maori legend
The demigod Maoui pulled up a great fish, and how his brothers hate pulled that fish into pieces, carving out valleys, mountains and forming the shape of the land. These stories of powerful primeval forces have parallels in our modern understanding of plate tectonics, which have been around for about 4 billion years, ever since the earth first formed.
The formation of Aotearoa
100 million years ago, the old supercontinent of gonwana and lauraisa, were beginning to be torn to pieces. Africa and North and South America were almost the same as they are today in the modern world. At the bottom, Australia and Antarctica were fused together. (NZ) Was sitting at the eastern edge of Gondwana. Superheated magma rose up against the bottom of the crust, stretching it and opening the deep fissures and fault lines. Sometimes magma reached all the way to the surface forming long chains of volcanoes. Eventually a huge section of land broke away from Gondwana land and went sailing into the pacific ocean, this “continent” was Zealandia. Meanwhile (the dinosaur extinctions and bird domination) the land was still changing. First Zealand got stretched and it sank, which left behind only a scattering of small islands. Then Zealandia, was shoved up against the Australia’s plate and a bit of crust right on the boundary was pushed upwards, land (NZ) rise up from the sea.
New Zealand’s tectonic plates colliding
In the south, we have a trench (one plate goes underneath another plate) the austrailian plate is going underneath the pacific plate for about 200km deep. Along this plate boundary there are many earthquakes. In the central south island the plate collision is mostly taken up by movement across the alpine fault. Much of the earthquake activity on the Alpine fault is sideways movement with some upwards movement. The upwards movement causes a very very strong boundary between Westland and the high peaks of the Southern Alps.
The motion of tectonic plates
Hot rock rises, heated by the earth’s core. Near the surface the rock spreads in two directions and goes sideways. It begins to lose heat and the much cooler rock sinks back down.- This is called a convention current. Through this spreading process, the earth’s crust is very slowly dragged apart and it causes the continents to move. Where the plates collide, the rock on the sea floor, containing carbon from the dead plankton, is carried deep into the earth. As it descends, this layer of rock is heated, so the rock melts, releasing CO2 and gas is returned back into the atmosphere during an eruption (of a volcano)
Plate Boundaries
Plates move as flow as your fingernails grow. Boundaries that converge: come together. Diverge- pull apart/ divide , transform- slide past each other.
When plates converge, they can push up each other and make mountains, or subduction occurs and the volacanos form.
When plates diverge the crust splits apart so it causes the magma to rise from the mantle below, and depending if it happens at the land or on the sea, this process form mid ocean ridges or rift valleys.
When plates transform, they slide and grind. This process is not smooth so the plates will jerk and the break. And in the sudden release these cause violent earthquakes.
The tectonic rock cycle
