NOTES- THEORY OF PLATE TECTONICS
Name_________________________Class__
1a. What are tectonic plates? Lithosphere- the _________________ and _______________ upper
layer of mantle, broken up into _______________________ called tectonic plates.
1b. 3 types of ____________________________
1) ________________________ = low-density silicate rock (granite)
2) ________________________ = dense, Iron/Mg rich rock (basalt)
3) A combination of __________________________ and ________________________
2. Where are tectonic plates found? The plates are Earth’s ______________; but unlike an eggshell,
these pieces are always being _____________________ , ____________________ , or moved.
3. How is plate movement explained? The ___________ ___ ____________
_______________
- How tectonic plates move around on a plastic layer of the __________________ called the
asthenosphere.
4. What are the 3 plate boundaries? There are 3 kinds of boundaries:
1) Divergent   = __________________________________________ boundaries
2) Convergent   = _________________________________________ boundaries
3) Transform   = _________________________________________ boundaries
5. What are mid-ocean ridges? Divergent = spreading boundaries
Mid-ocean ridge- An undersea mountain range with a ____________ __________________
running through the center of it.
Hot _____________________ rises to the surface, cools as _______________, and the
new _____________________ spreads out.
6. Mid-ocean ridges = rift zones
Rift- cracks in the center of a _____________________ where magma,
which is _______________ _______________ than rock, flows upward.
7. Mid-ocean ridges = rift zones
Rifting causes new crust to _____________ the older crust _____________ ; they are
divergent, or ________________________, boundaries.
8. What is paleomagnetism?
Iron inside the Earth makes Earth a ________________ _____________ .
When hot magma __________ __________ , the bits of iron in the ________________
will point to the poles like a compass needle.
9. Paleomagnetism = ______________ __________________ __________________ .
_______________ in new crust pushes the ______________ ______________ aside;
they record their polar-charge for thousands of years.
10. The magnetic poles have ______________________ in the past, and the rocks on the sea-floor
show this change.
11. Proof for the Theory of Plate Tectonics :
1) Recording movement at ________________ _______________________ (earthquakes).
2) Studying how magma forms new crust at ______________________________ and
______________________________ (rifting).
3) Observing that many ______________________ are occurring near plate boundaries,
such as, the Ring of Fire.
Paleomagnetism