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Landforms: Erosion & Mountain Building
What kind of erosion is occuring on the
upper slopes of Mount Rainier?
GLACIAL EROSION:
GLACIERS ARE SCRAPING AWAY THE SIDES OF
THE VOLCANO OVER THOUSANDS OF YEARS.
Yosemite Valley, California was
sculpted out by glaciers during the last ice
age, leaving a bowl shaped valley with
steep sides.
What kind of erosion
sculpted the smooth
walls of
this canyon?
WIND
EROSION:
ND & WIND SCULPT
THE ROCKS OVER
THOUSANDS
OF YEARS.
WIND EROSION
SA
What type of erosion created
the deep canyon of the
Colorado River?
WATER
EROSION: Water
cuts through layers of
rock over thousands of
years.
Mount St Helens, before the
eruption of 1980.
The eruption of
Mount St Helens,
May 1980.
Super heated
gasses from the
blast flash-melted
snow and ice and
caused a massive
mudflow.
A giant hole was
formed at the top and
side from
the blast.
Mount St Helens today: Mountain building continues as a
dome is built up in the crater.
GEOLOGY
Mountain
Building
GEOLOGY
The earth has
many layers inside
with a solid inner
core.
Underneath the earth's crust is a molton layer
of very thick, liquid magma called the mantle.
The earth's crust is broken into large pieces called
plates. These plates can move because they are on
top of the mantle layer.
Over long periods
of time, the earth's
plates have moved
and changed
locations.
We see evidence of fossils on all 7
continents.
The San
Andreas
Fault,
California,
(seen from
an airplane.)
One plate is moving
north and one is moving
south.
The Teton Mountains in Wyoming were created by a slip
fault - one piece of the earth's crust is uplifted (the Tetons)
and one piece of the earth's crust is sinking (the valley
floor).
The Olympic Mountains were created from a
subduction zone, where one plate slips under another
plate.
SUBDUCTION ZONE:
One plate slips under
another plate.
Volcanoes ring
the Pacific Ocean
showing where
the oceanic and
continental plates
collide.
This is one of the many volcanoes
in the Aleutian chain off the coast
of Alaska.
Cascade Volcanoes, Oregon: Looking north
from Middle Sister: Belknap Crater, Mt.
Washington, Three Fingered Jack, Mt.
Jefferson, and Mt. Hood.
Scientist hypothesize
that the India landmass
drifted into the Asian
plate about 10 million
years ago.
This created the tallest
mountains in the world,
the Himalayan
Mountains.
Review: How are mountains made?
Mountains can be made by:
1. Plates colliding, causing some parts of the earth's
crust to be uplifted.
2. Volcanoes, like the ones seen all along the "Ring
of Fire".
Review: How are mountains torn down
or eroded away?
Erosion can be caused by:
1. Water (like the Grand Canyon)
2. Wind erosion (like in the desert Southwest)
3. Glaciers (like on Mount Rainier)
4. Mudflows - water mixed with earth
materials (like when Mount St. Helens
erupted.
5. People can cause erosion too by removing
plants from the ground, making wind or water
erosion more likely to happen.