Erosion, Deposition and Weathering

Weathering anticipation guide

• Take 5 minutes to complete the anticipation guide on the half sheet of paper that you picked up today

Erosion• Erosion is the transportation of weathered, or broken

down, sediment (small pieces of rock).• Wind, Water and the movements of the earth are

variables that can cause erosion.• Erosion=the movement/transport of sediments

http://www.youtube.com/watch?v=zE4j-vScBwo

http://www.youtube.com/watch?v=R48zYr-S7v0

Deposition• Deposition is when sediment, and broken

down substances are deposited, or laid down somewhere.

• This can happen in a river when the water slows and creates a new bank. When wind slows down it can also drop sediment.

Erosion and deposition go hand in hand!

• Erosion= the movement of sediment.• Deposition= The process of sediment settling

in a new location after it has been moved by erosion.

Review Questions: Think, Pair, Share! (erosion or deposition?)

1. Wind picks up sand in a sand storm. ___________

2.Sediment from a river is carried down the river by the current. _____________

3. Small pieces of rock that have been moved by a rain settle at the bottom of the river. ___________

4. An earthquake cause a landslide, and rocks and soil flow down a mountainside. _____________

5. Rocks, soil and sediment from a landslide stop moving and settle at the bottom of a mountain. ____________ 6. Explain the difference between erosion and deposition.

Weathering

• Weathering is the process that breaks down rocks when they are exposed to weather: rain, temperatures and chemicals.

Mechanical (Physical) Weathering

• Mechanical (physical) weathering is the breaking down of rock that involves physical processes.

• Types of Mechanical Weathering:– Frost Wedging– Biological Activity– Abrasion

Frost Wedging

• Frost wedging is caused by the expansion of water within tiny cracks during the freezing process. – Freezing rock can exert

tremendous pressure, enough to break solid rock.

Biological Activity

• Biological activity is when natural processes or living organisms break apart rocks into smaller pieces. – Example: Trees

Abrasion

• Abrasion is the rubbing of one rock against another. – This can happen during a

landslide or running water.

Review

• Complete the review questions on mechanical weathering.

Chemical Weathering

• Chemical Weathering is the breaking down of rock through chemical processes; causes chemical change.

• Types of chemical weathering:– Oxidation – Acid

Oxidation

• Oxidations is a chemical reaction involving oxygen. – Example: rust

Acid

• Acid occurs naturally in the environment and breaks down rocks. – Example: acid rain

Review

• Answer the two review questions over chemical weathering.

Mechanical vs. Chemical

Show me a 1 for mechanical and a 2 for chemical.

Two rocks scratching at the bottom of a glacier.

MECHANICAL!

Two rocks scratching at the bottom of a glacier.

•Acid rain dissolving calcite in marble.

CHEMICAL!

•Acid rain dissolving calcite in marble.

•H2O expanding within cracks when it undergoes a phase change.

MECHANICAL!

•H2O expanding within cracks when it undergoes a phase change.

•Rust forming on exposed iron-rich rocks.

CHEMICAL!

•Rust forming on exposed iron-rich rocks.

•Roots from a tree splitting rocks in half.

MECHANICAL!

•Roots from a tree splitting rocks in half.

•The Statue of Liberty’s skin turning green after years of exposure.

CHEMICAL!

•The Statue of Liberty’s skin turning green after years of exposure.

Weathering Lab

• Take 2 minutes to silently read over the procedures.

• Next we will assign group tasks

Weathering Lab

• Team Tasks:– Supply Collector• Picks up all supplies and returns them at the end of the

lab. – Timer• Records time for the group

– Recorder• Writes down all observations and notes• Makes sure team members copy down observations

– Team Leader• Keeps all teammates on task• Makes sure area is clean when finished with the lab

Exit Slip

1. What is the difference between the erosion and deposition of sediment?

2. What is chemical weathering?3. Give an example of chemical weathering. 4. What is mechanical weathering? 5. Give an example of mechanical weathering.