Transcript Weathering and Erosion

Changing Earth’s Surface
Weathering and Erosion
Changes to Earth’s Surface
 Earth’s crust is constantly in a process of change
 Weathering
 Erosion
 Deposition
Weathering
 The process by which
rocks are broken down
into small pieces called
sediment
 Caused by

Wind

Water
Glaciers
Meteorites
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Erosion
 Occurs when
weathered material is
carried away by wind or
water
 Responsible for some
of our most impressive
natural monuments

Example—The Grand
Canyon
Deposition
 Occurs when sediment
is dropped off at a new
location


Wind or water slows
down or comes to a
stop
Example—River Delta
Changing Earth’s Surface
Volcanoes
Plate Tectonics
 Theory that the lithosphere is divided into
plates that are always moving
 Pangaea

Supercontinent that once existed over 350
million years ago

Evidence: Puzzle piece fit of the continents, fossil
and soil matches on different continents
 Responsible for the formation of volcanoes
and earthquakes
Volcanoes
 Form when magma
rises to Earth’s
surface
 Pyroclastic Flow
Ashes, Gases, and
Magma that ooze or
explode from
volcanoes
 Can form at divergent
boundaries or
subduction zones
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Divergent Volcanoes
 Plates above the asthenosphere separate
 Magma rises up
 As lava cools, new crust is formed
 May be oozing or explosive
Divergent Volcano
Subduction Volcanoes
 Formed when a denser
ocean plate sinks under
a lighter plate (either
ocean or land)
 Magma comes to the
surface
Shield Volcano
 Broad and flat volcano
 Resemble a shield
laying on its side
 Built up slowly over
thousands of years,
most often in layers of
hardened lava
 Mostly ooze lava from
vents

Example—Mauna Loa,
Hawaii
Composite Volcano
 Formed of alternating
layers of ashes and
hardened lava
 May be dormant for
many years before
exploding rapidly or
may ooze for thousands
of years

Example—Crater
Lake, OR
Cinder Cone
 Formed from blobs of
congealed lava in a
simple cone shape
 Capable of violent
explosions
 Bowl-shaped crater at
the summit

Example—Paricutin,
Mexico
Changing Earth’s Surface
Earthquakes
World Earthquake Map
Earthquakes
 Energy released from the snap and slide of
Earth’s crust at a fault line
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Fault
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Focus
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2 or more plates slide past one another
Point inside Earth where an Earthquake begins
Epicenter

Point on Earth’s surface where Earthquake
waves begin
3 Types of Seismic Waves
 Primary (P) Waves
 Fastest and Smallest
Waves
 Secondary (S) Waves
 Medium Waves
 Surface (R) Waves
 Slowest and Most
Dangerous Waves
Earthquake Waves
 Measured with a
seismograph
 Scaled using the
Richter Scale

Scale of 1-10
 1 = least amount of
damage
 10 = greatest
amount of damage