Weathering - 10/17/11

Bell Ringer1. 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?

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.

KEY WORDS

• Weathering –Chemical weathering –Mechanical weathering

• Erosion • Unconformities

Why do we find small rocks?How do rocks get so small??

How do mountains get worn down to become pebbles?

• 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.

There are TWO kinds of weathering

MechanicalChemical

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

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

Unconformities

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.

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

What did you discover on your Gallery Walk?

Discovery Streaming Clip

• http://www.youtube.com/watch?v=lvKkPFoRiaw (breaker and woosh)

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?

Discuss

• How does weathering contribute to unconformities?

• How do unconformities change scientists’ understanding of Earth’s history?

Venn DiagramExit Ticket

Create a Venn Diagram Comparing and Contrasting Chemical and Mechanical Weathering.

You should provide at least 2 facts for each section.