Wk 10 – 15/7
Grade 5 Science
Changing Earth – Earth's crust
Earth’s structure
Imagine you’re a miner digging for gold or gems. You dig deep into Earth,
maybe 2 or 3 km down. But even at this depth, you’ve barely scratched
Earth’s surface. You’d need to dig down about 6000km to reach the center
of earth! What do you think you’d find at the center? Rock? The whole
Earth seems to be rock, but it isn’t. Earth has 4 layers – the crust, the
mantle, the outer core, and the inner core. The layers are different from
each other.
5-70km. The
crust is the surface
layer of Earth.
Mantle 2885km. The
mantle has 2 parts: the
upper mantle and the
lower mantle.
Inner core 1210km
Outer core 2270km
The inner core is iron
The hot outer core is liquid
and nickel. Even though
iron.
the core is very hot, great
pressure at the center of Earth
keeps the inner core solid.
The inner core is at the center of the Earth.
Earth’s crust is divided into sections, called plates. Plates are blocks of
crust and upper mantle rock that fit together like puzzle pieces. There are
10 major plates. Plates “float” on the softer rock of the mantle. As rock
flows, plates move. At different places, plates move toward each other,
away from each other, or along each other. These movements may cause
changes in Earth’s surface.
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What causes Earth’s plates to move?
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Earthquakes
Press your palms together as hard as you can. If one slips, energy is
released suddenly and your hands move past each other. When two of
earth’s plates move suddenly past each other, energy is also released and
the ground shakes. An earthquake is movement of the ground caused by
sudden release of energy in Earth’s crust. The place in the crust where
energy is released is called the focus. The point on Earth’s surface directly
above the focus is called the epicenter.
Most Earthquakes occur along a fault or break in earth’s crust.
Earthquakes caused by plates or pieces of crust pushing together or sliding
past each other are usually very strong. Earthquakes caused by plates
pulling apart are usually weak.
____
What causes an earthquake?
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Volcanoes
Melted rock under Earth’s surface is called magma. Magma gets pushed up
through the mantle and crust. As magma moves upward, it sometimes
reaches an opening in the crust. Magma that has flowed out of a vent is
called lava. Lava is molten rock that reaches earth’s surface. As more and
more lava flows from a vent, a volcano begins to form. A volcano is a
mountain made of lava, ash, or other materials made from eruptions.
Draw a volcano
Types of Volcanoes
Composite volcanoes are wide with
steep slopes.
Shield volcanoes are broad
with gentle slopes.
Cinder cone volcanoes are tall
and narrow with steep slopes.
Look at these volcanoes erupt!
http://news.discovery.com/v
ideos/earth-top-5-volcanowebcams-and-videos.html
Even though we normally draw and hear about composite volcanoes, there
are other kinds.
How mountains form
Mountains are the tallest landforms on Earth. They form where the crust
is crumpled and pushed upward by the movements of plates.
Many mountains form where plates come together. The edge of one plate is
pushed down and the edge of the other plate is pushed up, forming
mountain ranges for example the Himalayas.Or, they form in the middle of
a plate. Imagine a biscuit, push down on opposite edges, soon it breaks
down the middle with the jagged edges moving up.
See how mountains form!
http://www.youtube.com/wa
tch?v=ngV66m00UvU
How do mountains form?
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My Dictionary
inner core: __________________________________________
outer core: __________________________________________
mantle: _____________________________________________
crust: ______________________________________________
plates: _____________________________________________
earthquake: _________________________________________
epicenter: __________________________________________
fault: _____________________________________________
volcano: ____________________________________________
magma: ____________________________________________
lave: ______________________________________________
mountains: __________________________________________