Our Changing Earth:

1
Our Changing Earth

• Geologic Evolution

2
Station 1 Law of Superposition

• Law of Superposition
• states that the oldest rocks lie on the bottom
  and the youngest rocks are on top of any
  undisturbed sequence of rocks.
• Geologic Evolution

DOG RED TAR
Grand Canyon
3
Station 2 Relative Dating

• uses information about rock layers and the fossil
  record to determine the age relationships between
  rocks.
• Basically, putting them in order

Oldest Book Video Super Nintendo Compass N64
Disk Cell Phone CD Oldest Jimmy Rollins
Why?
4
Station 3 Absolute Dating

• Measuring the age of an event or object in years.
  The actual age for a rock or mineral.
• How do we do it?
• Using the atomic make up of a sample, we can
  find its absolute (exact) age.
• Half-life ? The amount of time for half sample
  isotopes to decay onto another substance.

5
Half-life
of half-lives Percentage left
0 100
1 50
2 25
3 12.5
4 6.25
5 3.125
6 1.56
7 .753
YOUNGER
OLDER
6
For Example Carbon-14 Dating

• All living things contain Carbon-14, when they
  die the Carbon-14 decays into Nitrogen-14
• Carbon-14 breaks down at a constant rate.
• Half life is 5,730 years
• Using carbon-14 we can date once living things.
• Only good up to 75,000 years
• How many years does it take 200g of carbon-14 to
  turn into100g of carbon-14?
• How long does it take for 200g of carbon-14 to
  turn into 50g?

7
Station 4 Ice Cores

• Ice cores work just like rock layers, and can
  tell us things like
• Major events (Volcanoes)
• Climate
• Gasses in the Atmosphere
• Hold bacteria and other life

8
Station 5 Continental Drift

• Ever think that South America fits like a puzzle
  into Africa? Scientists do.
• Continental Drift Theory theory that states that
  the gradual shifting of Earths plates causes
  continents to change their global positions over
  time.
• Pangaea (Super-continent) ? Today
  (Still moving)

9
Station 6 Unconformity

• What happens when a rock layer is disturbed?
• Unconformity Gap in the rock layer.

Unconformity
10
Station 7 Weathering (Chem/Mech.)

• Chemical Weathering the process that breaks
  down rock through chemical changes.
• Mechanical Weathering Weathering that occurs
  when rock is physically broken down into smaller
  pieces.