Download Notes-Plate-tectonics-fall

PLATE TECTONICS- the Earth’s crust is broken
up into chunks that move around on the surface. This
movement is responsible for:
 Volcanoes
 Earthquakes
At some point in the 1500’s, a map maker noticed
that it looked like South America and Africa fit
together.
In the 1800’s, a geologist said all the continents used
to be one land mass that broke apart. He called this
land mass Gondwanaland.
In 1912, Alfred Wegener proposed
CONTINENTAL DRIFT, which is a process for
how this single land mass drifted apart to form the
continents as they are today. He called the single
land mass PANGAEA. (This is the one that is
known today.) He gets the credit because he:
 Used the continents’ shapes
 Used rock data (matching rock types on South
America and on Africa)
 Used fossil data (matching fossils on S.A. and
Africa)
to back up his continental drift theory.
The plates move by MANTLE CONVECTION.
The mantle is the layer of Earth just below the crust.
Convection is where heated mantle rises towards the crust
and cooler mantle sinks closer to the core. This sets up a
circular motion.
Let me show you a video:
http://www.schooltube.com/video/ce265828750dd9a8270f/
Layers%20of%20the%20Earth
 This circular motion “carries” the plates around- that
is- it causes them to move. It’s kind of like you on a
treadmill. If you didn’t walk—if you just stood still,
the treadmill would cause you to move backwards
(and eventually fall off, but plates don’t fall off the
Earth because it is round. )
Another short video:
http://www.schooltube.com/video/9958ac73cff88eab6b7
4/mantle%20convection%20cells%20and%20continental
%20drift.wmv
Plate boundaries—where the tectonic
plates “meet”, there are THREE things
that can happen:
1. Divergent boundary= Where two plates are
spreading apart. More plate is being formed
there because of the magma coming up
through the crack between the two plates.
*Usually happens on the sea floor.
Ridge
2. Convergent boundary= Where two plates are
coming together. -3 types:
A. Oceanic-oceanic
B. Oceanic-continental
C. Continental-continental
*In A&B above, the oceanic crust gets
subducted, or sucked down below, the other
crust to form a trench.
*At a continental-continental convergent
boundary- Mountain ranges form.
3. The third type of boundary is transform
boundary. The crust slips by each other at
these boundaries. *See pg. 459. These are
also known as Faults.
Volcanoes- happen at convergent boundaries
where subduction happens.
Earthquakes- happen mostly at transform
boundaries, but can happen at all three types
of boundaries.
NOW, PLEASE READ SECTIONS 17.3 AND 17.4 IN
YOUR TEXTBOOK, THEN ANSWER THE
FOLLOWING QUESTIONS:
TURN IT IN WHEN DONE. THANKS!!
Questions 1, 3-5 pg 447,
Questions 1-4 pg 459 and
Questions 1-5, 10, 11, 14, 26 pg 468