Download EES 202 - Geological processes powerpoint

Science for living
Us 18982
Demonstrate a Knowledge of Earth
Science
2 credits
Element 1: Describe the structure of
the Earth.
• Features of the Earth include the mantle, core,
crust and plates.
• THE STRUCTURE OF THE EARTH
crust
mantle
Outer
core
Inner core
1
Think about?
• What moves when there is an Earthquake?
• What comes out of volcanoes?
• What is the pumice that you find around
Taupo Lake?
• Which section is the hottest?
• Which section contains liquid metal?
• Which section contains solid metal?
LAYERS OF THE EARTHwhat’s it made up of?
• Crust – thin, solid rock. Broken into about 20
plates.
• Mantle – molten rock (magma), heated from
the core and moving in convection currents
which moves the plates.
• Outer core – mainly molten iron and nickel.
• Inner core – solid iron due to immense
pressure.
NB: as you move deeper into earth pressure and
heat increases.
Movement of plates caused this
Tectonic plates
• Crust is divided into plates which move
around on the moving magma below.
• They can collide or pull away.
• They cause volcanic activity.
• They cause Earthquakes as the plates collide
and rocks break.
• Ring of Fire is the edges of the pacific plate –
the collisions cause a lot of volcanic activity.
THE MAJOR TECTONIC PLATES
PLATE TECTONICS
• Earth’s crust is made of around 11 large tectonic
plates and several smaller ones.
• Convection currents in the Mantle cause the plates
to move slowly.
• Plate tectonics (movement) cause Earthquakes and
volcanic activity.
• Plates consist of continental crust and oceanic crust.
• NZ lies on the boundaries of the Pacific and
Australian plates.
San Andreas Fault – Tectonic Plates colliding – North American
Plate and Pacific Plate.
COLLISION OF THE AUSTRALIAN
AND PACIFIC PLATES
New Zealand's deep
earthquakes from
1990-1994
become deeper from
east to west
THREE GROUPS OF ROCK MAKE UP THE
EARTH’S CRUST
Igneous – formed when magma cools and solidifies, in
an around volcanoes.
Sedimentary – formed from sediment (sand, pebbles,
shells) at bottom of a body of water, eg, lake, river,
sea, swamp.
Metamorphic – formed when other rocks are heated
and compressed deep within the Earth’s crust,
often near magma.
Sedimentary Rocks
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Sediment wash down into the ocean.
They may contain shells or fossils.
Layered.
Sediments are cemented together.
They are pushed up out of the water by
tectonic plate movement.
• Eg, Sandstone, Limestone
Sandstone
• Sedimentary.
• Formed on the
beach from
sediments of sand.
• Soft, grainy.
• Mudstone is also a
sedimentary rock
with fine particles.
• Predominant in
Marlborough as
Greywacke.
Limestone
• Limestone is found in
cliffs.
• It has fossil shell remains
in it because it was
formed on the beach
which has shellfish on it.
• A hard sedimentary rock
which is often the last to
erode.
Limestone of Cathedral Caves
Sawcut gorge
davidwallphoto.com
Igneous Rocks
• Rocks are pushed down into the mantle and
become molten.
• Molten rock cools in the crust to form solid,
igneous rocks.
• Or, the magma comes out of the Earth
through a Volcano and cools and solidifies.
• It will cool fast if it comes out (extrusive) and
will have small or no crystals, eg, Basalt.
• Slow cooling inside the crust (intrusive) will
produce larger crystals, eg, granite.
Basalt
• Fast cooling
Magma.
• Small crystals.
• Dark coloured.
Granite
Granite
• Magma cools slowly, often in cracks in the
crust.
• Gives time for mineral crystals to form in the
rocks.
• Pretty.
Metamorphic
• Rocks are pushed down near the mantle or
under mountains.
• Intense heat from the mantle and/or pressure
from above cause the rocks to change.
• They become very hard and pretty.
• Eg, Pounamu (jade), Marble.
Pounamu
• Metamorphic.
• Formed by heat and
pressure.
Marble
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Metamorphic.
Formed in the same way as jade.
Formed from limestone.
Often used to make benches and
ornaments.
Marble
The rock cycle – how rocks change