1. 3.how mountains are formed 2 3 it takes millions of years for mountains to form even though they...
TRANSCRIPT
1
3. How Mountains are Formed
2
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
4
Mountains can be formed when plates that make up Earth’s
crust moveconvergent
divergent
transform
5
Some mountains are formed when two plates push against
each other (converge)
The pressure causes one plate to bulge out
6
Often the bulge is round and is lifted into the shape of a dome
Dome-shaped mountains are usually low mountains
7
Vocabulary
Dome-shaped mountains
Mountains formed when two plates push against each other (converge) and one plate bulge
out
8
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
9
Sometimes when plates collide, the rock breaks into blocks
It is pushed up along fault lines.
10
These broken blocks form fault-block mountains
Mountains, like the Sierra Nevada in North America, are often steeper than other kinds
of mountains
11
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
12
Some mountains begin when one plate is forced down below
another plate.
The rock in the lower plate melts then rises to the surface
13
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
14
As the melted rock cools, it forms a hard layer
More layers are formed as the lava piles up and cools
15
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
16
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
17
The longest range in the world is the Andes in South America
18
The Andes Mountains are found along the edge of the South
American Plate
19
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
20
They are 1.4 billion years old and formed what we call
“Elephant Rocks”
21
Another series of igneous rock has been exposed near
Eminence
where the Current and Jacks Fork Rivers have formed
Rocky Falls Shut-In
22
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
23