Geological History
Earth’s Formation
• http://www.youtube.com/watch?v=QDqskltCix
A
• Watch this video FIRST, and take a few notes
on the formation of Earth.
• Then after the video you will have 3-4 minutes
to write down a paragraph 4-5 sentences long
that summarizes the formation of Earth…
• I will pick 3 people to read.
First, What is Earth Like Inside?
• Write down a diagram in your notes and
describe the layers of the Earth…
• Describe if each layer is liquid, solid, hot,
cold…ect.
What is Continental Drift?
• Proposed by Wegener-1915
• Theory that states that all the plates move
and the continents were once a single
landmass which split apart…Pangaea
• Precursor to theory of plate tectonics
Evidence for Plate Tectonics
• What 3 pieces of evidence do you think we
have for continental drift?
• List them in your notes.
Evidence 1
• All of the continents fit
together like a puzzle
Evidence 2-Fossils
• Identical Fossils were located directly opposite on
widely spaced apart continents
Evidence 3-Rock Type
• Similar rock
types, age and
structure found
on different
continents
• Ex:Appalachians
and mountains in
Scotland/Scandinavia
Why do plates “float” and what
do they float on?
• Isostasy- The crust floats on the mantle
since the crust is less dense.
• The heavier the crust, the more it will push
on the mantle
• Mantle is not “liquid” like we think of it…it
has plasticity.
Isostasy Examples
• In areas formerly covered by ice sheets (around
the Baltic Sea and Hudson Bay, for example),
sea cliffs and beach ridges are now found
nearly 300 m (1000 feet) above sea level!
• Why?
How do plates push apart?
• http://www.youutbe.com/watch?v=CFtce8bYJO8
• Convection:
http://www.youtube.com/watch?v=ryrXAGY1dmE
• Sea Floor Spreading- Magma pushes up in a ridge
on the ocean floor and creates new crust—pushing
the crust apart
• In ocean trenches the crust moves down and melts
Proof of Seafloor Spreading
• Paleomagnetism– The Earth’s magnetic field
has reversed throughout
history.
– The element iron in the
rocks in the ocean crust
orients to the magnetic field
as it is forming.
– Distinct patterns show the
rock has the same
orientation as it spreads
apart.
Before the Bell…
• Take out your Google Earth Tour
• Answer this question in your notes (4-6
sentences)
– What is the theory of plate tectonics…be
specific…and what proof do we have? What
drives plate tectonics…
Results of Plate Movement
• Earthquakes- (this video puts it all
together!)https://www.youtube.com/watch?v=cavq2HF
Ba-U
• Current World Earth Quakes (Google Earth)• Tsunami Animationhttp://www.youtube.com/watch?v=4Xebwzb3dDE
• Tsunami Footagehttp://www.youtube.com/watch?v=RDOuwMj7Xzo
• https://www.youtube.com/watch?v=w3AdFjklR50