External Processes

Erosion Weathering

Directions:

- Click “Slide Show” then “View Show” to view the power point.

-Record all notes and complete all tasks in your notebook.

- If a page doesn’t have a directions box like this, just get the notes.

Weathering

• Weathering - forces that are changing rocks and land over time, even day to day.

Mechanical WeatheringMechanical weathering – when a force breaks a rock into smaller pieces by forcing them apart.

- Breaking large rocks into smaller ones

Causes of Mechanical Weathering

• Roots growing through rocks - root wedging

• Ice gets into rocks, expands the space it inhabits – frost wedging

• Thermal expansion – rocks in deserts get heated and expand, breaking them into pieces.

Causes/Effects of Mechanical Weathering

Directions:

-Click on the headline to bring up the website.

- Click on the pictures to make them larger. Read the captions.

-Record the examples of mechanical weathering that could occur in Houston.

Chemical Weathering

• Chemical weathering - when something "eats away" at a rock rather than breaking it apart.

• Key Idea*** MUST HAVE A CHEMICAL CHANGE IN THE ROCKS.

Causes of Chemical Weathering

1. Acid Rain

Directions:

- Click the mouse to bring up the 5 steps.

- Briefly explain each step of the Acid Rain process in your notebook.

Causes of Chemical Weathering

2. Water – creates a chemical reaction in certain rocks

3. Chemicals – resulting from pollution or internal processes

Foaming pollution on rocks.

Effects of Chemical Weathering

At PH1, this New Zealand lake is pure hydrochloric acid

Naked trees

Rust

Analysis

1. How is mechanical weathering like a hammer?

2. Create a weathering wonderland. - Sketch a landscape that includes examples of

weathering resulting from each of the 6 causes. (3 mechanical, 3 chemical)

- Label each cause- See a sample on the next slide to help you begin.

You can steal my example for thermal expansion if you want.

- Your wonderland can have multiple rock formations.

Rocks that have split apart due to thermal expansion.