Plate tectonics states the earth's crust is broken into plates which can move.
 

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Geological
Period
Millions of
Years Ago
 
Three main types of plate boundaries: convergent, divergent and transform.
 
Divergent Boundary
Convergent Boundary
Transform Boundary
 
Mountains form by uplift.
 
 
The half-life of a radioactive element can't be changed.
 

The diagram above represents a cube of radioactive material (Figure A) cut into eight identical cubes (Figure B).
Half-life of both samples are the same since you cannot change an elements half-life.

 
Index fossils are good time markers (widely spread, lived a short time).
 

Notice that this type of fossil is found over a wide area and (not shown) was short lived

 
Undisturbed strata - bottom layer is oldest.
 
 
Intrusion and faults are younger than the rock they are in.
 
 
Uranium 238 (U 238) dates old rocks.
 
Half life for U 238 is
4.5 x 10 9 years
 
Carbon 14 dates recent living objects.
 
 
Use your Earth Science Reference Tables! This is one of the most important tools in your test taking arsenal.
 
 

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