Download Mountains - Mrs. Murphy Earth Science

The North Face of
Mount Everest
Himalayas, Northern India
Mountains
By Jeanie Lacob 2014
What are mountains?
• A landform that reaches a high elevation.
• For a hill or mound to be classified as a
mountain, its summit, or highest point, must
be more than a few hundred meters above
the land around it.
Mt. Fuji in Japan
Mountain Systems
• Most mountains do not stand alone, they are
part of a group of mountains.
• A group of mountains with the same general
shape and structure is called a mountain
range.
• Groups of mountain ranges form into what
are called mountain systems.
• Some scientists break up mountain systems
into two major groups, called belts.
• These belts, shown below are called the
Eurasian-Melanesian belt and the CircumPacific belt.
How are mountains formed?
• When tectonic plates collide, land features
that start as folds and faults can eventually
become large mountain ranges.
• Mountains exist because tectonic plates are
continually moving around and colliding with
one another.
Sierra Nevada in California
How do mountains
change?
• Over millions of
years,
mountains
change and take
on different
forms.
• Mountains
change as the
crust is either
built up or worn
away by various
processes.
How do mountains change?
Some mountains have steep slopes. The peaks are
sharp and jagged and the valleys are narrow.
These
mountains
are often
called
“young”
because they
are formed
from new
crust.
• As time passes, a mountain’s peak is worn
down by weather conditions which make the
peak more rounded and the slopes become
less steep. These mountains are sometimes
called “mature” mountains.
San
Bernardino
Mountains of
California
Some mountains continue to be worn away for
a very long time. These “old” mountains are
almost flat and have no jagged peaks. They
have rolling hills and the valleys between these
mountains are wide.
For example the
Appalachian
Mountains
How are mountains classified?
• Mountains are classified based on how they
formed.
• There are three main types:
– Volcanic
– Folded
– Fault-block
Appalachian Mountains in the U.S.
Volcanic Mountains
• Formed from lava or debris, such as ash or
rocks, thrown out of a volcano.
• They are built up from eruptions that occur
over thousands or even millions of years.
• Mount Fuji in Japan
Mt. St. Helens in USA
Folded Mountains
• Mountains formed by the folding of rock layers.
• Most are formed at convergent boundaries where
continents have collided.
• They form when rock layers are squeezed together and
pushed upward.
• .
Folded Mountains
• The highest mountain ranges in the world are made up
of folded mountains.
• Example: Himalayas in Asia
Upwarped folding:
Black Hills,South Dakota
"Hog backs" looking north
along edge of Colorado Front
Ranges west of Boulder, CO.
Anticline: fold of rock that bends upward in an arch
Syncline : a fold of rock that
bends downward in the
middle to form a “U”
Anticline or syncline?
The famous Rainbow
syncline near
Basin ________
Barstow, CA
syncline
Folded Mountains
Appalachian Mountains
Fault-Block Mountains
• Formed when tension causes large blocks of the
Earth’s crust to drop down relative to other blocks.
• Mountains that have sharp, jagged peaks.
• Example: Sierra Nevada Mountains in California
Fault-Block Mountains
• Formed when tension causes large blocks of
the Earth’s crust to drop down relative to
other blocks.
Fault-Block Mountains
• Mountains that have sharp, jagged peaks.
• The Grand Tetons in Wyoming & the Sierra
Nevada in California are fault-block
mountains.
Fault-Block mountains: Teton Range, Sierra Nevada
Mountains that have sharp, jagged peaks.
Grand Tetons, Wyoming are examples of fault block mountains.
What are Plains?
• Large, flat areas that are just above sea level.
• They slope gently over great distances.
• They can form from uneven land being worn
down by weather conditions or from material
being deposited in a large body of water .
• There are two types of plains:
– Coastal (located in
coastal areas)
– Inland (located inland)
The Great Plains in Montana
What are Plateaus?
• Have much higher elevations than plains, yet they are
also large, flat areas.
• The same forces that build mountains form
plateaus.
Island in the Sky Plateau, Canyonlands National Park Utah
What are Plateaus?
• Many have canyons, which are steep-sided
valleys formed by a river.
The same forces that build mountains form
plateaus.
Colorado Plateau