1. Weathering - 10/17/11
Bell Ringer
1. Fossils of warm-weather plants were
found on an island in the Artic Ocean.
What can best be concluded from this
discovery?
2. Convection currents in Earth’s mantle
are believed to be responsible for?

2. Demonstration
When I tell you, place the starburst in your
mouth, but DO NOT CHEW!
I will let you know when you can chew.
Chemicals in your saliva break down the candy
bar.
When you chew, your teeth physically break up
the candy into smaller pieces.

3. KEY WORDS
• Weathering
–Chemical weathering
–Mechanical weathering
• Erosion
• Unconformities

4. Why do we find small rocks?
How do rocks get so small??
How do mountains get worn
down to become pebbles?

5. • Weathering is how rocks are
broken, worn down, changed in color or
composition by the action of
water, air, plants and animals.
• Weathering happens to rocks in place--
there is no movement of the rock
involved.

6. There are TWO kinds of
weathering
Mechanical Chemical

7. Types of Weathering
• Mechanical Weathering- does NOT
change the substance, it just makes it
smaller
– Ex: A rock breaks in half
• Chemical Weathering- CHEMICALLY
CHANGES the substance, usually
indicated by a color change.
– Ex: A limestone statue gradually becomes
grey and black over time and worn down
from acid rain

8. Vocabulary
• Weathering: Rock is broken down
• Chemical Weathering: Chemicals break
down rock.
– Ex: Acid Rain
• Mechanical Weathering: Big rocks are
broken into small rocks.
– Ex: Ice wedging
• Unconformity: A gap in the rock record

9. Unconformities

10. Gallery Walk
• Answer the following at each:
1. Describe the picture.
2. Is this an example of mechanical or
chemical weathering?
3. How do you know?
Stay at each “painting” until time is called.

11. Gallery Walk Expectations
• You WILL work with your tables- NO ONE ELSE
• Noise level is at a “talking side by side” level.
• You will remain at your “painting” until the music
stops – you will not move ahead.
• EACH column of gallery walk feedback form is
filled in WHILE you are at that station.
• You will keep hands, feet, objects to YOURSELF.
• Warning: If YOU MAKE THE CHOICE to not meet
these expectations, YOU have MADE THE
CHOICE to complete work alone, silently in your
seat.
Make the RIGHT CHOICE 

12. What did you discover on your
Gallery Walk?

13. Discovery Streaming Clip
• http://www.youtube.com/watch?v=lvKkPF
oRiaw (breaker and woosh)

14. Write Time! (In your
notebook, write at least 3 complete
sentences)
How was the candy demonstration
similar to chemical and mechanical
weathering?
Which step was CHEMICAL?
Which step was MECHANICAL?

15. Discuss
• How does weathering contribute to
unconformities?
• How do unconformities change
scientists’ understanding of Earth’s
history?

16. Venn Diagram
Exit Ticket
Create a Venn Diagram Comparing and
Contrasting Chemical and Mechanical
Weathering.
You should provide at least 2 facts for
each section.