1. 3.How Mountains are Formed 2 3 It takes millions of years for mountains to form Even though they...
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Transcript of 1. 3.How Mountains are Formed 2 3 It takes millions of years for mountains to form Even though they...
3
It takes millions of years for mountains to form
Even though they rise high above the ground, mountains
begin forming below the surface of the Earth
5
Some mountains are formed when two plates push against
each other (converge)
The pressure causes one plate to bulge out
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Often the bulge is round and is lifted into the shape of a dome
Dome-shaped mountains are usually low mountains
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Vocabulary
Dome-shaped mountains
Mountains formed when two plates push against each other (converge) and one plate bulge
out
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Fold mountains are formed when plates collide head-on
Vocabulary:
Fold mountains
The folding of the Earth’s crust to form peaks when 2 plates
collide head-on
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These broken blocks form fault-block mountains
Mountains, like the Sierra Nevada in North America, are often steeper than other kinds
of mountains
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Vocabulary
Fault-block mountains
Mountains formed by blocks of rock that are pushed up along
fault lines and the rock is broken when the plates collide
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Some mountains begin when one plate is forced down below
another plate.
The rock in the lower plate melts then rises to the surface
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This hot melted rock, or lava, spews out of the ground
Vocabulary:
lava
Hot melted rock spewed onto the surface of the Earth by a
volcano
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As the melted rock cools, it forms a hard layer
More layers are formed as the lava piles up and cools
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In this way, a volcanic mountain is formed
Vocabulary
Volcanic mountain
A mountain formed when layers of lava pile up on the
surface and cools
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Most mountains are formed in a group, or range
Mountains in a range have about the same shape and are usually made of the same kinds
of rock
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The oldest exposed igneous rock in North America is in
Missouri
The St Francios Mountains in eastern Missouri were formed through volcanic and intrusive
activity
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Another series of igneous rock has been exposed near
Eminence
where the Current and Jacks Fork Rivers have formed
Rocky Falls Shut-In
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Missouri has a third are of isolated igneous rock exposed
between Lebanon and Camdenton
It is thought an asteroid hit the area causing the sedimentary
rock to be removed