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Chp. 1
Mountain Building pg. 13- 17
3 Types of Mountain Building
Note: Mountains result from plate movements.
The 3 types of mountains / mountain building:
1.) Formed by Folding
2.) Formed by Faulting
3.) Formed by Volcanic Activity
Fold Mountains
Folding: is the process that occurs when continental plates
collide causing the crust to bend and buckle (crust looks
like a roller coaster ride).
- The rock layers bend, but do not break.
See fig 1.12 in text  creation of Himalayan Mtns. (tallest
in world)
Compressional forces are at work here.
Anticline: the peak or top of a fold in the rock layers.
Syncline: the trough or bottom part of the fold in the
rock layers.
Fault Mountains
Faulting: is the process that occurs when the crust
fractures or breaks apart.
- Due to compressional and tensional forces.
- Faults may be short or hundreds of kilometers
long.
Four types of faults:
1.) Normal
2.) Reverse
3.) Block
4.) Overthrust
1.) Normal Faults: Caused by tensional forces. When the
land moves apart at a fault line one plate drops down lower
than the other. The land that rises above can form a
mountain.
2.) Reverse Faults: Caused by compressional forces when
plates move together at the fault. The land that rises above
can form a mountain.
3.) Overthrust fault: A fault that has already
undergone “folding”. One set of rock layers has been
pushed up and thrust over other rock layers.
4.) Block fault: Occurs when a piece of the earth’s
crust is moved upwards between two parallel fault
lines. ( Rift Valley occurs when a piece of the earth’s
crust is moved downwards.) Fig. 1.13 in text.
Volcanic Mountains
Volcano: An opening in the Earth’s crust through which
magma, gases, and ash erupt.
Magma: Molten or melted rock found below Earth’s crust.
When magma cools to a solid it forms igneous rocks.
Lava: magma that flows at the Earth’s surface.
Ash : Small pieces of lava that are blasted into the air
during volcanic eruptions.
Vent: The opening through which the volcanic material
flows.
Ash and Cinder Cone
- The simplest type of volcano.
- Symmetrical shape, steep sides, large crater. A single
vent.
- Very explosive. Lava is thick and slow flowing, often
blocking the vent  Boom!
Shield Cone
- Shape is broad and flat.
- The volcano is built of lava, which nearly always flows
from the vent.
- Eruptions are milder / the least explosive.
Composite Cone
- Shape is similar to ash and cinder, except it is built
of layers of ash, cinder, and lava.
- A network of magma vents develop inside, forming
mini-volcanoes.
- Eruptions can be explosive, followed by periods of
quiet activity.
Complete Questions 14-16 pg. 16