Transcript Changes to Earth`s Surface

Changes to Earth’s Surface
Chapter 6
Prior Knowledge
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What are the layers of the Earth?
What causes Earth’s surface to
change?
What causes earthquakes?
Describe a volcano and how it erupts.
Lesson 1
How Does Earth’s Surface
Change?
Layers of the Earth
1.
Crust (0-100 km thick) The thin outer
layer of Earth, including dry land and the
ocean floor.
• This is the thinnest and least dense
layer.
• The crust is thick under continents and
thinner under oceans.
Layers of the Earth
2. Mantle - The thick layer of the Earth
beneath the crust
a. Upper part is rigid, like Earth’s crust.
• Underneath it is a thick zone of hot,
soft rock.
Layers of the Mantle
b.
•
c.
Lithosphere - (1.6-130 km thick)
is the crust and the stiff upper part
of the mantle
Moho - The Mohorovicic
Discontinuity is the boundary
between the crust and the mantle,
where seismic waves change
velocity.
Asthenosphere (72-250 km thick)
is the lower part of the mantle
which is made up of iron and
magnesium silicate minerals. This
layer is said to have plasticity
because it is hot, soft and can flow.
Layers of the Earth
4.
Core - The layer of Earth extending
from the Earth’s center to the bottom of
the mantle. It is mostly iron and nickel.
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Outer core (2200km thick) is made of very
hot liquid iron and nickel. The movement of
the outer core produces Earth’s magnetic
field.
Inner core (1250km thick) is very hot but
the pressure from the layers around it make
it into a solid metal ball.
Wind, Water, & Gravity Change
Earth’s Surface
5.
6.
Weathering - The process by which rock
is broken down into smaller pieces.
Erosion - The removal of transportation
of weathered materials.
a. Gravity - is a powerful tool that causes
erosion.
Wind, Water, & Gravity Change
Earth’s Surface
7.
8.
Sediments - small pieces of rock
that are weathered and eroded and
carried by wind and water.
Deposition - is the dropping or
settling of eroded material and
occurs very close to where sediment
was originally produced.
9. How do wind, water and
gravity change Earth’s surface?
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They weather, erode and deposit
materials.
Ice Changes Earth’s Surface
10.
GlaciersA large sheet of moving ice
that stays frozen year around.
11. What are the 3 ways that glaciers can
chance the landscape?
1. Glaciers can carve out areas of Earth’s surface.
2. Deposit large piles of sediment.
3. Can cause the land to uplift when glaciers
retreat.
Impacts Change Earth’s
Surface
12. Meteorites- rocks from space
13. What causes Craters to form?
Meteorite impacts cause craters to
form.
6-2 What Are Plates and
How Do They Move?
1. Plate Tectonics -The theory that the
lithosphere is divided into plates that
are always moving, breaking apart,
and colliding!
2. Most plates are made up of both
oceanic and continental crust.
3. Look at the maps on pages 308-309.
Compare the North American plate
with the Pacific Plate?
North American plate is smaller and has
more continental crust than the Pacific
plate.
Plate Boundaries
4. The three main types of plate boundaries are:
1. Divergent boundary -a place where 2 or more plate
are moving AWAY from each other.
a)
b)
c)
Mid-Ocean Ridge - a chain of mountains beneath the
ocean.
Rift - highest part of the mid-ocean ridge where plates
move apart.
Sea-floor spreading - new lithosphere formed along the
mid-ocean ridge from the ocean bottom cooling and
becoming rigid.
Plate Boundaries
2. Convergent boundaries - Where 2
plates move TOWARD each other.
3. Transform Fault Boundary - 2 plates
moving PAST each other.
a. San Andreas fault in California is
a famous transform fault boundary
where Earthquakes occur from
the plates grinding past each other.
Plate Movements change
Earth’s Surface
5.
Pangea - a supercontinent where all of
the continents were connected about 220
Million years ago.
6.
Why do scientists believe there was a
super continent that existed about 220
million years ago?
Pangea
6-3 What Causes
Earthquakes and Volcanoes?
1.
Fault - a break in Earth’s crust
where rock on one side can move in
relation to rock on the other side.
2.
3.
4.
Earthquake - A vibration in Earth's
crust, caused by the release of
energy at a fault.
Focus - The point inside Earth where
an earthquake begins.
Epicenter - The point on Earth’s
surface directly above the focus of an
earthquake.
5.
P waves - Fastest waved caused by
earthquakes, they compress and expand
the ground as they travel.
6.
S waves - Second-fastest waves caused by
earthquakes that move across the direction
the p waves are traveling. They can move
up and down or side to side.
7. What causes an
earthquake?
–Pressure along faults that is
released in the form of waves of
energy cause an earthquake.
Measuring Earthquake Strength
and Damage
1.
2.
3.
4.
Seismograph readings can be used to
calculate an earthquake’s strength.
Richter scale - estimates the amount of energy
released by an earthquake.
Moment Magnitude scale - uses the
amplitude of earthquake waves to estimate and
earthquake’s energy and fault rupture area.
Mercalli intensity scales - measure an
earthquakes damage.
5.
6.
Tsunami - A powerful earthquake that
occurs beneath the ocean that causes the
ocean floor to rise and fall and produces a
large destructive wave that can travel great
distances.
What are the effects of a tsunami?
Tsunamis flood costal regions and cause
major damage and erosion.
Volcanoes
1.
2.
Volcanoes - A mountain formed
when molten rock is pushed to
Earth’s surface and builds up.
What causes a volcano to form?
Magma that rises to Earth’s surface
and erupts from a vent causes a
volcano.
3. Types of volcanoes:
A.
B.
C.
Shield -broad, dome shaped that may
erupt many times in a period of more than
a million years.
Composite - may erupt on and off for as
long as a million years.
Cinder - have steep sides and erupt for a
short period of time. Most are less than
300m tall.
4.
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What caused the Hawaiian
Islands to form?
As the Pacific plate moved over a hot
spot, magma erupted and formed a
chain of volcanoes.