Transcript relative vs absolute

 What
is the difference between absolute
and relative age?
 What is the Law of Superposition?
Relative Age:
 Age of rock compared to the ages of
other rocks
• Ex: Steph Curry is younger than Kobe
Absolute Age:
 Number of years since the rock formed
• Ex: Steph Curry is 27 years old
Law of superposition:
 oldest layer is at the bottom and the higher
layer is younger than the one below it.
Radioactive Decay:
• Over time elements break down (decay) by
releasing particles (radiation)
• Half-life – the time it takes for half of an
element to break down
• Scientists can tell age of a rock or fossil by
measuring the amounts of certain elements
Index fossils:
 Help geologists match rock layers
 Must
time
be widespread AND live for a brief