Teacher Suggestions

1.  List all 16 of the tectonic plates.  What are considered the major 12?
 
 Eurasian (M)  Australian (M) Pacific (M)
 Cocos  Jan De Fuca North American  (M)
 Caribbean (M)  Antarctic (M) S. American (M)
 Scotia   Eurasian (M) Arabian (M)
 African (M)   Indian (M)  Nazca (M)
 Phillippine
 
 
2.  Describe the historical progression of the movement of tectonic plates from Pangaea to today.

a. 250 million years ago the ocean is called the Panthalassa. The one continent was
       called Pangaea.
b. 200 million years ago the Pangaea began to separate and break apart creating two new land masses called LAURASIA and GONDWANALAND
c. 135 million years ago break up of GONDWANALAND resulting in Africa and South America becoming separate land masses and India moving northeast toward Asia.
d. 40 million years ago North America and Europe separated, leaving Greenland behind. India continued to move northeast toward Asia.
 

3. Describe each of the 4 types of plate boundaries and give an example of each.
 
 Divergent boundaries -- where new crust is generated as the plates pull away from each other.
 Convergent boundaries -- where crust is destroyed as one plate dives under another.
 Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
 Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.
 
 
4. Describe convective flow and give an example.
 
 The mobile rock beneath the rigid plates is believed to be moving in a circular manner somewhat like a pot of thick soup when heated to boiling. The heated soup rises to the surface, spreads and begins to cool, and then sinks back to the bottom of the pot where it is reheated and rises again. This cycle is repeated over and over to generate what scientists call a convection cell or convective flow.  Convective flow can be observed easily in a pot of boiling soup.
 
 Convection cannot take place without a source of heat. Heat within the Earth comes from two main sources: radioactive decay and residual heat. Radioactive decay, a spontaneous process that is the basis of "isotopic clocks" used to date rocks, involves the loss of particles from the nucleus of an isotope (the parent) to form an isotope of a new element (the daughter). The radioactive decay of naturally occurring chemical elements -- most notably uranium, thorium, and potassium -- releases energy in the form of heat, which slowly migrates toward the Earth's surface. Residual heat is gravitational energy left over from the formation of the Earth -- 4.6 billion years ago -- by the "falling together" and compression of cosmic debris. How and why the escape of interior heat becomes concentrated in certain regions to form convection cells remains a mystery.