Weathering and Erosion• Weathering and erosion are two natural

processes that work together to shape the surface of the earth.

• Weathering is the breaking down of rock into smaller particles.

• Erosion is when any kind of rock material or soil is moved to another location.

What do you think contributed to the formation of this?

Can you see evidence of weathering and erosion taking place here?

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrape against

each other

Abrasion: mechanical weathering

Which rocks are you more likely to find on a river bed? Why?

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrape against

each otherIce wedging: when water in cracks freezes

and causes rocks to split

Ice wedging

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrape against

each otherIce wedging: when water in cracks freezes

and causes rocks to splitPlant action: when plant roots grow into rocks

and cause them to crack and split

Weathering by plants

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrap against

each otherIce wedging: when water in cracks freezes

and causes rocks to splitPlant action: when plant roots grow into rocks

and cause them to crack and split2. Chemical weathering wears away rock by

chemical reaction

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrape against

each otherIce wedging: when water in cracks freezes

and causes rocks to splitPlant action: when plant roots grow into rocks

and cause them to crack and split2. Chemical weathering wears away rock by

chemical reaction Dissolving by acid

Dissolving by acid

Remember our acid test? What was

happening to our rocks?

Stalactites

Stalagmites

Acid rain from pollution

Two types of Weathering1. Mechanical weathering is when rocks are

broken in smaller pieces by a physical forceAbrasion: when rocks knock or scrap against

each otherIce wedging: when water in cracks freezes and

causes rocks to splitPlant action: when plant roots grow into rocks

and cause them to crack and split2. Chemical weathering wears away rock by

chemical reaction Dissolving by acid Oxidation (rusting)

Chemical weathering

Oxidation

Weathering and Erosion• Weathering and erosion are two natural

processes that work together to shape the surface of the earth.

• Weathering is the breaking down of rock into smaller particles.

• Erosion is when any kind of rock material or soil is moved to another location.

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?Moving water; rain runoff, rivers, oceans etc.

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?Moving water; rain runoff, rivers, oceans etc.Wind; can carry sand, dust and soil

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?Moving water; rain runoff, rivers, oceans etc.Wind; can carry sand, dust and soilIce; glaciers and icebergs

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?Moving water; rain runoff, rivers, oceans etc.Wind; can carry sand, dust and soilIce; glaciers and icebergsGravity; mudslides, landslides and gradual creep

Gravity is the underlying force of erosion

Gravity

Sudden landslide Gradual creep

Erosion(moving of rock and soil)

• What can move rock and soil from one place to another?Moving water; rain runoff, rivers, oceans etc.Wind; can carry sand, dust and soilIce; glaciers and icebergsGravity; mudslides and landslides

Gravity is the underlying force of erosion

• Deposition: when rock or soil is dropped in a new place.

Can you see evidence of weathering and erosion here?

How might this rock have formed cracks?

Describe how these

gravestones probably look different from

when they were carved? What do

you think is responsible for these changes?

Homework

• Describe 4 ways that nature can break down rocks into smaller pieces.