Download Topic 4 PPT

POS
Unit 5: Planet Earth
Topic 4 The Moving Crust
Our earth is made up of
different layers:
1. Atmosphere “vapour” (air)
2. Hydrosphere “water”
(oceans, rivers, lakes)
3. Lithosphere “rocky”
(land)
4. Asthenosphere “weak”
(molten layer under
lithosphere, the mantle)
5. Biosphere: living layer
(plants/animals)
*Although the earth may seem very large, the layers we
inhabit, and require for our very survival are extremely
thin. Our planet is more fragile (viewed from the moon)
than we think. As small as we are, humans can bring
about major environmental changes.
How thin is the earth’s crust, the lithosphere?
It is like the shell on an egg,
or the skin of an apple
…very thin relative to the rest
Inside our planet
Layers:
Oceanic and Continental Crust (lithosphere)
5km-60 km deep
Mantle (1000-4000oC) (asthenosphere)
upper (more solid) and lower mantle (more liquid)
layer of molten rock, reason for movement of
tectonic plates, volcanoes, earthquakes
Core (5500-6000oC)
Outer-liquid iron Fe and nickel Ni (responsible for our
magnetic field
Inner-solid
*relative temperatures
Question: Why is the center of the earth solid?
* The inner core
should be a gas,
seeing how the
temperature is so
high (materials
expand as
particles move
farther apart) but
the high pressure
keeps the inner
core solid
Alfred Wegener
Hmm… did they ever fit together?
Movement
The crust is moving, as it floats in pieces on
the mantle
Why is the crust moving? Convection
currents!
Movement: Continental drift
Pieces: tectonic plates
But why are they moving?
Convection Currents
The SUPERCONTINENT
PANGAEA
*Pick out the continents
*Why is Asia mostly under water?
Gondwanaland/Laurasia
How old is the earth?
4.5 billion years
When did the dinosaurs go extinct?
65 million years ago
Continental Drift
Evidence:
1-Shapes fit
together
supercontinent
Pangaea
-broke into
Laurasia and
Gondwanaland
2-still moving today
measure distances,
see the trenches,
areas of sea floor
spreading
3-common fossils
Present day
Three major types of
movement
Transform Fault
 Slipping past
eachother
 The San Andreas Fault
 California, US
Converging Plates
 Moving towards eachother
 2 options:
 Mountain building (continental crust crashing into
continental crust)
 Subduction (continental crust sliding on top of oceanic
crust)
 Results:
 Earthquakes
 Volcanic eruptions
 Mountain formation
Convergence of Tectonic Plates:
Continental and Oceanic crust
Ring of Fire (Pacific)
The Pacific oceanic crust is subducting
underneath the continental crust of
surrounding plates
This causes widespread earthquakes and
volcanic activity
Ex) Japan, Philippines, California, Seattle (Mt.
St. Helens)
*Convection Currents
Hot gases/liquids rise, as the particles of
that material become less dense, and float
on the colder, more dense liquids/gases
https://www.youtube.com/watch?v=ryrXA
GY1dmE
1. Sea floor spreading
2. Subduction 3. Mountain formation
*Convergent or divergent?
Mid Atlantic Ridge
Sea-floor spreading
 Pushing apart North
and South America
from Africa and
Europe at a rate of
~2cm a year
Divergent boundaries
Diverging plates
Sea-floor spreading
Summary
Geysers-Old faithful
Yellowstone National Park
Deep Ocean Vents
Activities
 Activity pg 386 Give me a clue
 Answer Q’s #1-4 in your journals
 Glue map pieces in your journal “fitting together”
 Activity pg 388 What do the rocks tell us?
 Answer Q’s 1-3 and “What did you find out?” in your
journal
 Activity pg 389 The Spreading Sea Floor
 Answer “What did you find out” questions #1-3 in your
journals
 Tape/staple the paper into your journal
Assignments
Vocabulary
Update journals Topic 4
Evidence of plate tectonic movement
Technologies
Topic 4 Q’s pg 394 #1-5
Faces of Earth Video
 Disc A, Episode 1: Building the planet
 0:00-3:00 Intro
 3:00 (skip)- Avaris camera- high altitude plane, lydar
camera
 START 8:20 Formation of earth in space 4.5 billion years
ago
 10:20 magnetic field + aurora, need it to keep the
atmosphere/hydrosphere/biosphere
 16:00- beginning of atmosphere/hydrologic
cycle=hydrosphere
 17:30=life 3 billion years ago, cyanobacteria’s waste
product was oxygen (1st photosynthesis!) ozone
 20:00-skip iron, other more complex life
 26:00 extinctions
Faces of Earth
 cont. Disc A, Episode 1: Building the planet
 26:00 PT permian extinction: 95% of all life!
 Volcanism, Pangaea, altered atmosphere
 Noah’s ark?
 28:00 65 million years ago
 KT Cretaceous/Tertiary extinction
 Asteroid
 Dinosaurs, 50% of all life
 30:00 Fossil fuels
 Coal formation by compressed peat (plant debris)
 Natural Gas and Oil by microorganisms in the oceans
 33:00 (stop) rocks for oil + gas research, seismic
Faces of Earth
 cont. Disc A, Episode 2: Shaping the planet
 START 0:00 Intro: Divergent boundary in Ethiopia
(Iceland only other one on land), plate tectonics
 5:00-9:40 skip, tribe, monitoring, GPS
 11:00 tectonic plates
 13:00 mid Atlantic ridge
 14:00 ice age
 15:00-18:30 skip salt
 18:30 convergent mountain building, subduction
 23:00 volcanoes : Mt Vesuvius (Pompeii, Herculaneum)
 27:00 normal fault
 28:00 skip prediction
 33:40 Himalayas, seismo, earthquakes
 38:00 California, San Andreas Fault
 42:00 P, S waves
 44:00 END
Faces of Earth
 Disc B Episode 1: Assembling America
 Mount Rainier erupts, Seattle WA
 Subduction, water in volcanoes=explosive
 Cascade range
 Earthquake + seismograms
 Ultralight aircraft over scab-land (monster flood)
 Salt lake Utah
 Yellowstone Geysers…some truth to supervolcano
 Great Lakes
 Appalachian mountains (Himalaya sized in Pangaea)
 31:00 comet crashed
Faces of Earth
 Disc B Episode 2: A human world (boring!)
 Weather, climates, ice ages
 Ice cores
 Caused by change in earth’s orbit around the sun, or
wobble of the earth’s axis
 Cultural evolution as part of environmental change
 Metallurgy, mining
 Global warming
 … now it is us who are changing the face of earth by
construction + demolition