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/gladasked/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 Pair

Share

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…