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RESTLESS EARTH - CHAPTER 4
continental crust​
- Composition is similar to granite and forms the continents
and the areas of shallow seabed.
oceanic crust​
- Composition similar to basalt. It is thinner, denser, and younger
than the continental crust.
Structures of the Earth:
https://www.youtube.com/watch?v=WwiiOjyfvAU
crust​
- The outermost layer of the Earth. It is also the thinnest layer of the Earth.
mantle​
- This is the layer of the Earth between the crust and the core. It is
extremely thick and contains most of the Earth’s mass.
core​
- The core extends from the bottom of the mantle to the center of the Earth.
It is made mostly of iron, with smaller amounts of nickel and possibly some
sulfur and oxygen.
outer core​
- The liquid layer of the Earth’s core that lies beneath the mantle and
surrounds the inner core.
inner core​
- This is the solid, dense center of our planet that extends from the
bottom of the outer core to the center of the Earth.
lithosphere​
- The outermost, rigid layer of the Earth. This is made up of the crust
and the upper part of the mantle. The lithosphere is divided into pieces called
tectonic plates​
.
asthenosphere​
- “weak sphere” A soft layer on the mantle on which pieces of the
lithosphere move. It flows very slowly.
mesosphere​
- A strong lower part of the mantle. It extends from the bottom of
the asthenosphere down to Earth’s core.
https://www.youtube.com/watch?v=aoV4dmXIt_8
Tectonic Plates:​
Pieces of the lithosphere that move around on top of the
asthenosphere. These are pieces of a jigsaw puzzle.
continental drift​
: A theory that continents can drift apart from one another and
have done so in the past. It also explained why fossils of the same plant and
animal species are found on both sides of the Atlantic Ocean. Ancient species
could not have made it across the ocean. It explained puzzling evidence left by
ancient glaciers.
http://www.sciencechannel.com/tv-shows/greatest-discoveries/videos/100-gre
atest-discoveries-continental-drift/
Sea-floor spreading​
- The process by which new oceanic lithosphere is created as
older materials are pulled away. As tectonic plates move away from each other,
the sea floor spreads apart and magma rises to fill in the gap.
THE THEORY OF PLATE TECTONICS
plate tectonics​
: The theory that the Earth’s lithosphere is divided into tectonic
plates that move around on top of the asthenosphere.
Convergent Boundaries​
: When two tectonic plates push into one another, the
boundary where they meet is called a c​
onvergent boundary​
.
Divergent Boundaries​
: When two tectonic plates move away from one another,
the boundary between them is called a d
​ivergent boundary​
.
Transform Boundaries​
: When two tectonic plates slide past each other
horizontally , the boundary between them is called a ​
transform boundary​
. The
San Andreas Fault in California is a good example.
https://www.youtube.com/watch?v=kwfNGatxUJI
Deforming the Earth’s Crust
Stress​
: The amount of force per unit area that is put on a given material.
Example: With a small amount of stress, uncooked spaghetti bends. Additional
stress causes it to break.
Compression​
: The type of stress that occurs when an object is squeezed (two
tectonic plates collide).
Tension​
: A form of stress that occurs when forces act to stretch an object.
Folding​
: This occurs when rock layers bend due to stress in the Earth’s crust.
Fault​
: The surface along which rocks break and slide past each other is called a
fault​
. The position of the fault block determines whether it is a hanging wall or a
footwall.
Normal Fault​
: The movement of a ​
normal fault​
causes the hanging wall to move
down relative to the footwall.
Reverse Fault​
: The movement of a ​
reverse fault​
causes the hanging wall to move
up relative to the footwall.
Strike-Slip Fault​
: This occurs when opposing forces cause rock to break and
move horizontally. The ground would appear to move left or right.