New Zealand’s Natural Landscapes How we got what we have

Outline Relief and landforming processes Plate Tectonics Processes to produce landforms Faulting Folding Volcanism Landmodifying processes Erosion

Relief and landforming processes

Plate Tectonics

Processes to produce landforms

Faulting

Folding

Volcanism

Landmodifying processes

Erosion

Relief and landform processes

Plate Tectonics

Theory of Plate Tectonics The surface of the earth is covered by crustal plates which collide or are pulled apart from one another (fig 1) They are driven by convection currents (fig 2) Figure 1: Plate tectonics theory says the earth is made up of interlocking crustal plates Figure 2: Beneath the earth’s crust

The surface of the earth is covered by crustal plates which collide or are pulled apart from one another (fig 1)

They are driven by convection currents (fig 2)

Plate margins – Where the action is! Plate margins are where plates collide, move past, slide past or spread apart There are three types of plate margin Destructive plate margin Fig 1 Constructive plate margin Fig 2 Passive plate margin Fig 3 Figure 1: Destructive plate margin Figure 2: Constructive plate margin (sea floor spreading) Figure 3: Passive plate margin

Plate margins are where plates collide, move past, slide past or spread apart

There are three types of plate margin

Destructive plate margin

Fig 1

Constructive plate margin

Fig 2

Passive plate margin

Fig 3

Destructive plate margins Where plates move towards each other one is forced under the other, called subduction The thinner oceanic plate is forced under the thicker continental plate

Where plates move towards each other one is forced under the other, called subduction

The thinner oceanic plate is forced under the thicker continental plate

Constructive plate margins Where plates are moving apart sea-floor spreading occurs The magma rises into the cracks between the plates, this causes mid-oceanic ridges

Where plates are moving apart sea-floor spreading occurs

The magma rises into the cracks between the plates, this causes mid-oceanic ridges

Passive plate margin Where the plates are moving past one another it is known as a conservative boundary Crustal rock is neither destroyed nor created

Where the plates are moving past one another it is known as a conservative boundary

Crustal rock is neither destroyed nor created

Tectonics of NZ

Processes to produce landforms

Faulting Faulting is the movement of the crust along zones of weakness Generally plate margins As pressure builds old, brittle rocks break and move in blocks The land shifts upwards, downwards or sideways The southern Alps of NZ have been uplifted by faulting

Faulting is the movement of the crust along zones of weakness

Generally plate margins

As pressure builds old, brittle rocks break and move in blocks

The land shifts upwards, downwards or sideways

The southern Alps of NZ have been uplifted by faulting

Folding Folding is the process where sedimentary rock is pushed and squeezed as surrounding hard rock is moved by plate tectonics The soft rock bends and twists This creates more gentle landscapes The North Island hill country has been formed by folding

Folding is the process where sedimentary rock is pushed and squeezed as surrounding hard rock is moved by plate tectonics

The soft rock bends and twists

This creates more gentle landscapes

The North

Island hill

country has

been formed

by folding

Volcanism Subducting oceanic rock melts and then escapes to the surface through a weakness Typical volcanic landforms are lava or ash erupted from volcanoes Calderas, lake Taupo Thick deposits of ash, the Volcanic Plateau Old lava cones, Auckland volcanic field

Subducting oceanic rock melts and then escapes to the surface through a weakness

Typical volcanic landforms are

lava or ash erupted from volcanoes

Calderas, lake Taupo

Thick deposits of ash, the Volcanic Plateau

Old lava cones, Auckland volcanic field

Land modifying processes

Erosion Once land is formed other processes occur to change or modify the landform This wearing down and transportation of the earth’s surface is known as erosion This occurs by Weathering Transportation Deposition

Once land is formed other processes occur to change or modify the landform

This wearing down and transportation of the earth’s surface is known as erosion

This occurs by

Weathering

Transportation

Deposition

Weathering The breaking down and wearing away of the land by chemical processes Some of the these processes are Fluvial erosion Erosion by running water Glacial erosion Periglacial erosion Freeze thaw Aeolian erosion Coastal erosion

The breaking down and wearing away of the land by chemical processes

Some of the these processes are

Fluvial erosion

Erosion by running water

Glacial erosion

Periglacial erosion

Freeze thaw

Aeolian erosion

Coastal erosion

Transportation Once the material has been broken down by one of the chemical processes it is moved from that place Some of the forms of transportation are Fluvial Running water Glacial Aeolian Coastal

Once the material has been broken down by one of the chemical processes it is moved from that place

Some of the forms of transportation are

Fluvial

Running water

Glacial

Aeolian

Coastal

Deposition Once the material has been transported it is put somewhere else This is known as deposition It is deposited somewhere Example A river transports material downstream Where the river is flowing fast it picks up a lot of material in its flow As the speed of the river slows it can’t transport all the material anymore, its not moving fast enough to hold it It then deposits that material

Once the material has been transported it is put somewhere else

This is known as deposition

It is deposited somewhere

Example

A river transports material downstream

Where the river is flowing fast it picks up a lot of material in its flow

As the speed of the river slows it can’t transport all the material anymore, its not moving fast enough to hold it

It then deposits that material