Movements of the Earth

1
Movements of the Earths Crust

• Harcourt Science
• Unit D
• Chapter 1

Mrs.Strand 6th grade Lockwood Middle School
2
What are the Earths Layers?

• Terms
• Crust
• Mantle
• Core
• Lithosphere
• Asthenosphere
• Plate Tectonics

3
What are the Earths Layers?
4
Earths Plates How they move
http//science.enotes.com/images/earth/woes_02_img
0118.jpg
Look in book pg D8 for names
5
Changes to the Earths Surface

• Erosion
• Wind
• Water
• Glacier
• Falling Space Material
• Meteorites

6
How the Earths Plates Move

• Terms
• Divergent boundary
• Convergent boundary
• Transform fault boundary
• Mid-ocean Ridge
• Rift
• Sea-floor Spreading

7
How Earths Plates Move

• Divergent Boundary
• Mid-ocean ridges
• May also occur on continents (Africa)

8
How Earths Plates Move

• Convergent Boundaries
• Crust is absorbed at convergent boundaries
• 1. Ocean plate collides with another ocean plate
• Causes deep trenches (mariana trench in the
  Phillipines)
• 2.Continental plates collide
• Forms some of the highest mountains in the world
  (himalayas)
• 3. Oceanic plate collides with a continental
  plate
• Forms mountains and volcanoes
• 80 of volcanoes and 90 of earthquakes occur on
  convergent boundaries.

9
How Earths Plates Move Transform Fault
Boundaries

• Two plates move past each other in opposite
  directions.
• Most occur in oceanic crust.
• San Andreas fault
• Earthquakes are common along these boundaries
• Mountains are very common

10
Earths Surface Changes Over Time
http//www.ucmp.berkeley.edu/geology/anim4.html
11
Earthquakes and Volcanoes

• Terms
• Earthquake
• Focus
• Epicenter
• P wave
• S wave
• Surface Wave
• Richter Scale
• Volcano

12
Earthquakes Volcanoes

• Plate movements cause earthquakes
• One million earthquakes each year. Only about
  200 earthquakes cause damage.
• Earthquake waves
• P waves faster, push-pull motion
• S waves slower, vibrations at 90 to the
  direction of travel
• Surface waves travel only at the earths surface
  and are the slowest waves

13
Earthquakes Volcanoes

• Earthquake Measurement

Two ways to Measure Earthquakes
The Modified Mercalli Scale expresses the
intensity of an earthquake's effects in a given
locality in values ranging from I to XII.
The Richter scale is logarithmic so that a
recording of 7, for example, indicates a
disturbance with ground motion 10 times as large
as a recording of 6.
14
Earthquakes Volcanoes

• How volcanoes form
• Along convergent boundaries

15
Earthquakes Volcanoes

• Types of Volcanoes
• Among the different kinds of volcanoes are
• shield volcanoes Unlike the composite volcanoes
  which are tall and thin, shield volcanoes are
  tall and broad, with flat, rounded shapes.
• cinder cones Cinder cones are simple volcanoes
  which have a bowl-shaped crater at the summit and
  only grow to about a thousand feet, the size of a
  hill. They usually are created of eruptions from
  a single opening.
• composite volcanoes They are built of
  alternating layers of lava flows, volcanic ash,
  cinders, blocks, and bombs.

http//www.windows.ucar.edu/tour/link/earth/inter
ior/volcanos_general.html
16
Earthquakes Volcanoes

• Hot Spot Volcanoes

Hot spots are areas in the earths mantle which,
for unexplained reasons, are hotter than the
surrounding mantle.
The Hawaiian Islands are recent volcanoes
produced by a hot spot that has given birth to
countless volcanic islands, which over time have
sunk into the sea to become atolls and seamounts.
Hot spot volcanoes can show us how plates have
moved in the past by leaving a trail of islands
or atolls. This map of the Hawaiian_Emperor
seamount chain shows us which way the plate was
moving throughout history