Download 12.13-plate-tectonics

APES 12.13
Please turn in your human population
FRQ and demographic transition activity
(the cut and paste one)
Find a pen/pencil (no scantron today)
Done Early?
• Grab a book and check your answers on
Module 24
• Re-read pages 264-267 in preparation for
the lab
Module 24 Multiple Choice
1. A – earth’s core is mostly Iron and Nickel
2. C- subduction is one plate passing under
another
3. B- Hawaii was formed at a hot spot (a
weakness in the pacific ocean plate where
magma was allowed to leak out)
4. B- see whiteboard
5. E- metamorphic rock is formed at high
temp/pressure
6. C- earthquakes occur mostly at transform
boundaries
Homework (Changed!)
• Take notes on the slides after this (7-33)
• Watch all of the short simulations
• Record 3 questions you have
This will be checked off like a homework
assignment- can type or hand-write.
• How do we know that the earth’s crust
(lithosphere) is split into plates that either
move towards, away, or laterally against
each other?
https://www.youtube.com/watch?v=ph7Eczs
-nTI
Earth Science AP Outline:
I. Earth Systems and Resources (10-15%)
A. Earth Science Concepts
(Geologic time scale; plate tectonics, earthquakes,
volcanism; seasons; solar intensity and latitude)
B. The Atmosphere (Ch. 4)
C. Global Water Resources/Use (after break)
D. Soil and Soil Dynamics (later this week)
What’s Inside the Earth?
Earth Profile by Texture
LITHOSPHERE
• Hard & brittle
• Earth’s Crust +Uppermost mantle
• “Plates”
ASTHENOSPHERE
• Highly Viscous
• 2nd Upper-most mantle
• Convection current
that carries the plates
Ocean and Continental Crust
OCEAN crust
• Denser
• Thinner
• Eventually subducted
• Relatively young
CONTINENTAL crust
• Less dense
• Thicker
• Rarely/never
subducted
• Oldest crust on Earth
Theory of Continental Drift
• Continents were formed from the drifting
apart of one super continent Pangaea
•
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0806/es0806page01.cfm?chapter_no=visualization
• Found evidence of similar fossils and
geological formations on different
continents
• The shape of continents also seemed to
“fit” together
Fossil & Geologic Evidence
Big flaw with theory:
How did the continents
actually move?
Theory of Plate Tectonics
• Outer “shell” of Earth is broken into plates
(lithosphere)
• Plates are carried by convection cells in
asthenosphere
• Moving plates collide, diverge, or slide by
each other
• Explained Alfred Wegener’s Theory of
Continental Drift
Convection cells in asthenosphere (upper mantle)
cause sea floor spreading
Convergent Boundaries
1. Continental/Oceanic
• Denser ocean crust is subducted under.
• Deep trench, strong earthquakes
• Energy of subduction often creates volcanic
mountain range on continent
http://education.sdsc.edu/optiputer/flash/subduction_5.htm
• Examples:
Andes Mts.
Cascade Mts.
•
http://www.publicbroadcasting.net/kplu/news.newsmain?action=article&ARTICLE_ID=1402653&sectionID=13
Convergent Boundaries
2. Oceanic/Oceanic
http://education
.sdsc.edu/optip
uter/flash/conv
ergance2.htm
• Slower plate is subducted (pulled under)
• Outcome = volcanic islands, strong earthquakes,
tsunamis, deep trenches
• Ex: Aleutian islands (Alaska), Hawaiian Islands, Japan,
Southeast Asia
Hot Spots
• Magma flows from a weak spot/vent in the
crust creating a volcano
• Crust above the vent is moving
• Forms a chain of land that varies in age
down the chain (i.e. Hawaii)
• Why is Nihau the oldest
Hawaiian Island?
Hawaii the youngest?
• What island still has
active volcanoes? In a
hundred years will it
still have an active
volcano? Why or why
not?
Types of Volcanoes
• https://www.youtube.com/watch?v=HdhARb2PGqA
• Composite = Alt. layers of lava flows, ash,
and cinder
• Infrequent but explosive eruptions
• Usually large and conical
• Occur along subduction zones
Ex: Mt Hood, Mt. Rainier, Mt Shasta
Cinder Cones
• Built above a vent from lava fragments
called “cinders” ejecting from the vent
• Steep, small eruptions
• Very common, form in groups or on the
edges of shield volcanoes
Craters of the Moon National
Monument in Idaho
Shield Volcano
• Built by large, non-explosive
lava flows
• Gently sloping
• Formed at hot spots,
sea floor spreading, and
occasionally subduction
zones
• Ex: Big IslandMauna Loa, Mauna Kea,
Kilaeua
Convergent Boundaries
3. Continental/Continental
• Continental Crust is light, so no subduction
• Instead, piles of crumpled, folded crust = tall
mountains
• Examples: Himalayan Mts.,
Appalachian Mts.,
Alps
Himalayan Formation
http://www.edumedia-sciences.com/en/a823-formation-ofthe-himalayas
Divergent Boundary
• Normal Fault
• Mostly below the ocean
• Sea Floor Spreading - Forms new crust
•
http://education.sdsc.edu/optiputer/flash/seafloorspread.htm
• Example: Mid
Atlantic Ridge, Rift
Valley in Africa
Great Rift Valley- Africa
Age of Seafloor
Transform Plate Boundaries
• 2 plates sliding in opposite directions
• E.g. San Andreas Fault
•
http://education.sdsc.edu/optiputer/flash/SanAndreas.htm
Faults
• Fractures in crust
• Occur along plate boundaries, but
occasionally occur in the middle of a plate
• Rigidity of crust builds up tension;
eventually slippage occurs to release
tension  this is an earthquake
What causes the seasons?
• Earth’s Tilt: 23.5 degrees.
• The rotation of the earth around the sun.
• Direct sunlight vs. Indirect sunlight.
Solar Intensity vs. Latitude
• Lower latitudes are
nearest to the equator
• They always receive
more intense sunlight
than “higher” latitudes
• N and S hemispheres
differ in solar intensity
depending on season