What Is Weathering?• The breakdown of rock into smaller and

smaller pieces This is where we are focusing today!

Sweet Tart Lab

• In your notebook create a new page in which you title the lab “Sweet Tart Lab”.

• Remember these are items that I will be looking for in the notebook check. Please ensure that your information is accurate and complete.

How Does Surface Area affect the Rate of Weathering?

• Demo: Sweet tarts and acid• PROBLEM: Which dissolves faster – a solid

SweetTARTS or a SweeTARTS that is broken up into smaller pieces?

• Create a hypothesis: Which sweet tart do you think will dissolve the quickest?

There are two main types of weathering

• Mechanical Weathering: the breakdown of rock into smaller pieces by physical means (ex: ice, water, gravity, plants)

• Chemical weathering: the chemical breakdown of rocks and minerals into new substances (ex: water, acid rain)

3. How does chemical weathering differ from physical weathering?

The way or method the rock undergoes to turn into small sediments (rock pieces)

4. What are some factors that affect the rate (speed) of chemical weathering?

Climate, humidity (moisture in the air) & temperature

How Does Surface Area affect the Rate of Weathering?

VARIABLES: 1. Independent variable:2. Dependent variable:3. Experimental Group:4. Control Group:

How Does Surface Area affect the Rate of Weathering?

VARIABLES: 1. Independent variable: Size of rock/ fragment2. Dependent variable: Speed of “weathering”3. Experimental Group: Rock broken into sediments4. Control Group: Rock in one piece

How Does Surface Area affect the Rate of Weathering?

MATERIALS:•5 Sweet Tarts •5 Sweet Tarts broken down “weathered”•2 cups•White Vinegar•TimerEXPERIMENTAL SET UP:Draw the set up in your notebook.

How Does Surface Area affect the Rate of Weathering?

OBSERVATIONS:During the experiment, write down 2 sentenceson what you see, hear, smell.. Ect.CONCLUSION: Accept or reject hypothesis?Finish this aspect of the lab using evidence from your observations. Write in complete sentences!Follow Up Question: Based on the results of your experiment, predict which of these would weather the fastest - a smooth round pebble or a jagged piece of rock. Why?

How Does Surface Area affect the Rate of Weathering?

Let’s take a deeper look…

Mechanical Weathering: WIND, WATER and GRAVITY

• Abrasion: the action of rocks and sediments grinding against each other and wearing away exposed surfaces

• When wind blows against exposed rock, the sand eventually wears away the rock’s surface

Mechanical Weathering: WIND, WATER and GRAVITY

• Example: Gravity can also lead to abrasion. As rocks are pulled down by gravity, they can start falling down mountains. As the rocks hit each other, they rub against each other causing abrasion to occur and leading to the weathering of rocks.

Mechanical Weathering: WIND, WATER and GRAVITY

• When rocks and pebbles roll along the bottom of swiftly flowing rivers, they bump into and scrape against each other.

• They eventually can become river rocks.

What happens when you freeze a coke can?

• The liquid expands, and often times the can will bust!

Mechanical Weathering: ICE Wedging• When water seeps into a crack in a rock during warm weather

and then freezes during cold weather, it expands. • And when it expands, it pushes against the sides of the crack,

forcing it to open wider. • This process is called ice wedging.

Frost WedgingWhen water freezes and expands, it enlarges cracks in rocks.

Biological Activity• Activity of organisms– Growing roots, burrowing

animals, deforestation– Life via plants or animals

accelerate weathering = breaking down of rocks into sediments

Mechanical Weathering: PLANTS

• Plants often send their roots into existing cracks in rocks.

• As the plant gets bigger, the force of the expanding root becomes so strong that the crack is made larger.

Mechanical Weathering: ANIMALS

• Almost any animal that burrows causes mechanical weathering

• These may include animals like ants, mice, coyotes, and rabbits

What is unloading

• It is the process which layers of rocks under the surface are exposed

• You need to know “unloading” is mechanical!

Checks for understanding

Which of the following is NOT a cause of mechanical weathering?

1. Dissolving2. Frost wedging3. Abrasion 4. Burrowing

There are two main types of weathering

• Mechanical Weathering: the breakdown of rock into smaller pieces by physical means (ex: ice, water, gravity, plants)

• Chemical weathering: the chemical breakdown of rocks and minerals into new substances (ex: water, acid rain)

Let’s take a deeper look…

• Answer the following question below your chart.

• What climate is best for chemical weathering to occur?

Chemical Weathering: WATER• Many types of rock can be dissolved by water• Even hard rock, like granite, is broken down by

water• It may take a few thousand years

Chemical Weathering: ACID RAIN

• Acid precipitation: precipitation that contains acids due to air pollution

• Precipitation such as rain and snow is naturally acidic and contains carbonic acid

• These acids can slowly break down rocks and other matter

Chemical Weathering: ACID RAIN• When fossil fuels

are burned, they give off gases, and when these compounds combine with water in the atmosphere, they can fall back to the ground in rain or snow

Chemical Weathering: AIR• In rocks that contain

iron, oxidation (rust) may occur

• Oxidation is a chemical reaction in which an element combines with oxygen to form an oxide (basically, the easy way to say this is that stuff rusts!)

Climate

Chemical Weathering happens in WARM & HOT

Checks for understanding

Which of the type of chemical weathering is responsible for turning the statue of liberty green?

1. Dissolving2. Acid Rain3. Abrasion 4. Oxygen

Checks for understanding

Which is responsible for creation of rust?

1. Dissolving2. Acid Rain3. Abrasion 4. Oxidation

Checks for understanding

In which climate does chemical weathering occur most rapidly?

1. Cold, dry2. Cold, wet3. Warm, dry4. Warm, wet

The Grand Canyon in Arizona

Anticipation & Connections

• Deposition: when weathered rock and soil particles build up in one place

• Weathering, erosion and deposition never stop. They are part of a continuous cycle.

Independent Practice

• Complete Tic-Tac-Toe board practice– Use all notes from Unit 3