More Patterns: Ages of Rocks
on Earth
How do we know how old rocks are?
• This isn’t our goal here.
• Most methods for dating rocks use
radioactivity – the process of atoms falling
apart at a predictable rate.
• To learn more, visit the Utah Geological
Survey at
http://geology.utah.gov/surveynotes/gladas
ked/gladage.htm
Can we compare age patterns
on Earth with other planets?
• No.
• To tell the age of a rock, it has to go to an
Earth lab
• So we know ages from the Moon, and
from chunks of Mars that ended up as
meteorites (about 120)
• But we don’t know many ages, and we
don’t know where the meteorites came
from on Mars.
Let’s look for patterns
• Find the handout called Age Patterns on
the Earth
• Find your maps:
– Age of Rocks on the Continents
– Age of the Ocean Floor
http://bc.outcrop.org/images/tectonics/press4e/figure-02-14.jpg
What do the different colors on this map mean?
http://www.lithosphere.info/TC1-2006/TC1_Fig2-ages-062006.jpg
What do the different colors on this map mean?
Time to think about the patterns
• Talk to your partner about the questions in
the graphic organizer. Fill in the chart.
Share what you figured out with
another partner
• In a minute you will find your Venus
partner.
• You will do a Structured Think Pair Share
with that partner.
• Make this chart in your journal:
Think
Share
Pair
Structured Think Pair Share
• First you will write what you think about
the question in the Think box.
• Then you and your partner will each
describe your ideas. Write your partner’s
ideas in the Pair box.
• Finally you and your partner will decide on
a common answer to the question. Write
that in the Share box.
Question:
• How are the age patterns on the
continents different from the age patterns
on the ocean floors?
Time to share
• Let’s make a class share sheet about age
patterns on the Earth.
One more Notice & Wonder
• Pull out your journal
• Make a N&W chart:
I noticed…
I wonder…